Matthew
13-08-2003, 11:18 PM
By Tony Murtagh
Ever had a problem with an OMF or file interchange? Who hasn’t? Will we ever get to where we will not have to rely on the EDL conform? A mixing facility is faced with the problem of audio being delivered on multi-formats, dialogue on Fairlight, effects and foley on DSP and music on Protools.
How do they read all formats?
Will we ever be able to develop a reliable universal interchange format?
Wouldn’t it be nice if picture editing came after sound so they could experience all the problems sound post experience with OMF files that don’t work?
These are some of the points we will look at in this article.
It is always dangerous writing an article about areas that utilise constantly evolving computer technology. Almost by the time you have written the article the goal posts have changed again. What I will endeavour to do in this article is gain feedback from both manufacturers and operators who regularly have to deal with file format interchange issues.
My thanks to the following people for being so generous with their time and information.
From the manufacturers:
Andrew Bell from Fairlight
David (Digby) Richards from DSP
From the operators:
Simon Leadley from Trackdown Studios (OMF in feature films)
Phillip Purcell from Tracks Television (OMF in television).
What are the most common file formats used in audio?
• The first type of files are audio media only files, containing only the recorded audio clips. These formats include AIFF and AIFC (developed by Apple), WAV (developed by Microsoft), Broadcast WAV and a number of proprietary formats.
• The second type of file contains audio media and can include video, EDL, editing information and additional meta data. These formats include OMF1, OMF2, AAF, and AES31. Audio file formats commonly contained in the OMF format include AIFF or WAV. In future formats, such as AAF, there is mention of including extra complex picture information such as telecine “Pan & Scan” and colour grading notes, etc.
Why do we need a common interchange format?
• Saving of time (and hence money) by removing the need for EDL conforms.
• No more double handling of audio material and therefore less editing time.
• Transfer flexibility of product between different workstations.
• Ensure authenticity of authorship by receiving a project that is identical to the final cut created by the picture editor and director.
• Preserve quality by using all digital transfers. (If the digitising assistants know what they are doing!!!!!)
• Save time not having to dub all source material to time coded formats.
• Mixing facilities can receive audio from multi-platform workstations.
All these points are very beneficial in sound postproduction - if it all works!
Credit should be given to Avid for initiating the file interchange process with the OMF format.
What is required to interchange file formats?
File exchange between platforms relies on three completely independent pieces of technology.
• The first aspect is the disk format that contains the media.
A number of different disk file systems currently exists. Fat16, Fat32, NTFS, HFS (Mac), and a dozen or so proprietary systems are out there in the market place including Fairlight, Akai, etc. If you want to read a file created by some body else the first thing you have to do is be able to read the disk containing the media. Similarly if you want to send this media to another party you have to be able to write it to a disk format they can read.
• The second aspect is the audio file format, that is to say the file in which the audio is stored. WAV, Broadcast Wav, AIFF, AIFC, and again many proprietary ones.
For example, Fairlight is able to read Akai’s file format because Akai provided information about their file format, and Akai can read Fairlight files because they provided them with information about their file format.
AES31 uses the broadcast wave audio file format and uses Fat32 as its disk file format. OMF doesn’t mandate either of those things. It allows you to use any disk file system and any audio file format. This is one of the reasons why it becomes so complicated.
• The third aspect is the audio EDL format - the “Edit Decision List” format. In digital audio workstations these are proprietary files in each companies case. In Protools it is called a session file, in Fairlight a project, in Akai’s case an AKL file, in AES31 an ADL, in OMF it’s all part of the OMF file. These three areas must be examined and adhered to very closely.
Where are we at currently?
• Even in the OMF format, there is not one confirmed standard. At present, across Sydney studios, there is a mixture of OMF1 and OMF2 files being used. For Protools, with the release of the Digidesign’s Digitranslator, more and more OMF2 files are being utilised. Currently the ABC, Beyond, and Tracks Television all use OMF1 file transfers. Trackdown, Philmsound and Soundfirm (on the Farscape project) have been using OMF2 with a good success rate. Simon Leadley mentioned, that for the last 4 years, Yoram Gross Studios have used OMF1 and OMF2 on all of their television series projects with transfers from Avid to Protools. The use of these formats (OMF1 or 2) seems to be growing and gaining supporters along the way.
What are the problems reported with the OMF process?
Where to begin? Both manufacturers and operators have experienced a number of problems.
Manufacturers problems:
One of the problems experienced, centres around the varying versions of software release. As most OMF files are currently created on Avids, independent sound facilities are now expected to handle OMF files created on multiple versions of Avid software, rangeing from version 6, 7, 8, and now 9, either Mac or NT. Fairlight, DSP, Protools and AMS, all at one time or another, have been able to open OMF files successfully, then all of a sudden files won’t open. The cause? New Avid software version release!!!!! It is then up to the DAW manufacturers to play catch up with this new software release by modifying their software.
Digby Richards: - DSP
“When Avid were running Version 6.5 we were 100% compatible and every one thought it was wonderful. Then Avid Version 7 came out!
We didn’t change our software. We didn’t change a thing, but all of a sudden the files didn’t go across for various reasons. It’s easy to point the finger and say, it’s not our fault, but…. I understand both AMS and Fairlight also experienced similar problems. We think we are doing everything right. We have the published spec’s for OMF, we follow it completely, then something changes from someone else and it doesn’t work.
This has been the story with OMF and why there have been problems with the format.
I was at an OMF developers conference two years ago and the highlight of the week was a report from a feature film editor. He was to come in and tell us about his success with OMF. When he got up to speak, he eventually said OMF transfer was full of problems.”
Andrew Bell: - Fairlight
“I think what they’ve really changed are the bits of OMF that they’re implementing. OMF contains features that are not universal to the audio industry. So if a particular company uses those features they may not be able to translate their audio into another format, or rather somebody else may not be able to get it out of the OMF format, as in group clips and sub clips. OMF also allows you to use any sort of processing you like.
In theory you’re supposed to define what this is, but that’s not really possible. This is processing that takes place in real time on the audio. For example there is a thing called a group object and you can specify any algorithm you would like to operate on that group. So the algorithm might mix them all together or it might play only the one with the most recent date on it. There are options and they are not specified by OMF. OMF just says you can add your own effect here. That is one of the biggest problems.”
TM: Should the specifications for OMF be more stringent?
Andrew Bell:
“Well there are arguments on both sides. You could say, lets reduce it to the most reasonable common denominator of features that most workstations have. This would result in a better success rate, but you would have people saying, well I want to do more on my workstation before I transfer it across. I don’t want to render all that to the audio because I want the next guy down the line to have the ability to unpick it if he wants to. This precise argument was expounded in great detail during the AES31 development. Now that’s the other side of the coin in most respects. It’s not sponsored or owned by one company. It’s not subject to anybody’s contractual control. It’s simply a standard that’s been created now and ratified.”
Operator problems experienced using OMFI:
• Varying versions of Avid software.
• Sub clips and group clips, used with multi-camera coverage.
• Audio media imported correctly but out of sync by 1 frame.
• Different sample rates: 44.1 or 48. If a post facility is clocked digitally to a set sample rate and an OMF arrives at a different sample rate problems arise.
• Audio digitised in “Draft” mode at 22 kHz.
• Incorrect Consolidation, not stripping off all Audiosuite effects, EQ, fades, level control, rubber banding, time compression, plug ins.
• Leaving extensions off a file name. (.OMF)
• Only 1 audio track digitised in.
• L+R summed to mono,
• Level too high (distorted), level too low (hissy).
• Audio media is off line.
• Formatting of the hard drive on to which the OMF is transferred is incompatible.
• Audio OMF files being transferred between different versions of Avid before being finally OMF’ed to Audio. (Offline Avid 6.5 to Online Avid 7.)
• Non time-code source tapes, if conform required.
I am sure there are many more. Many of these problems can be solved in the picture edit suite before the OMF is created. (continued next month.)
Operator comments:
Simon Leadley: - Trackdown
“OMF files will be received that have been created on very early versions of Avids which will only create OMF1 files. This means I have to keep versions of OMF tools, the first version being quite buggy, and this general means I have to supervise and keep a close eye on the conversion. It is essential that who ever is going to do the audio insists they go over to picture post and check the OMF process. Firstly they must check that the source material coming out of the Avid is OK before they even bother to make an OMF. Then the second thing is to go through the whole OMF process. I have virtually had to learn how to use the Avid in order to be able to assure that I could receive a useable OMF file. At the end of the day, to me, this is an area where I feel picture editors should be very comfortable with and understand how it works. However the process of creating the OMF file kind of falls between the cracks, in terms of whose responsibility it is. It’s like delivering the master tape to somebody in a way.
There was a film that took place recently and it took them two weeks to get the OMF to work. By this stage I think one of the guys had gone bald and the other guy had turned totally grey trying to get these files to open. I wasn’t directly involved, but after examining the files we discovered that not one single audio file referenced to this particular session existed on the hard drive they sent over. So in the OMF translation the program was looking for audio media that simply wasn’t there. The editor had done a consolidation, but completely not understood what a consolidation meant.
They had consolidated the project and then copied the wrong media files across. As there was a fundamental misunderstanding every time they created a new OMF, they made the same error. This is partly a problem in the way the Avid works. On one level it is very unfriendly to explain to you what’s going on because it tries to hide all the difficulties from you. For example you get an Avid file called AEDECB_EFGBA, you can’t tell easily what that means in a session. However in Protools it is a different story. (And Avid own Pro-Tools) They expect you to fiddle around with the files at the finder level and you know what is going on. Finally once we figured out what was going on with the OMF file it worked first go. This poor guy was going absolutely nuts. The problem was totally down to people who didn’t know what they were doing.
There are certain things you have to be aware of like deleting fade files, making sure there are not group clips in multi-cam shoots, whether the editor consolidates the files correctly and they understand exactly what the consolidation process does, that they completely understand what they are trying to do. Any one of those things you don’t understand will lead to an OMF that doesn’t work. What happens is, you receive a hard drive, a zip, or what ever from some body, but you can’t be absolutely sure how they have created that file. Is it an OMF1, is it an OMF2, what version of software, unless they have specially written down what it is, or given you a hint with the name they have called the file. Basically you sit there with every tool you’ve got and try and open this file.
Most of the OMF files we have received lately have been in the OMF2 format. The OMF2 files seem to work a little bit better at the moment. I think OMF2 is the way things are headed, and this can be seen by the new Digitranslator from Digidesign for Protools. The Digitranslator will only work with OMF2 files and not OMF1. This was pointed out to Digidesign and the reason they gave for only supporting OMF2 was because OMF2 had better specification than OMF1. In practice it was felt OMF2 was less buggy than OMF1. Digitranslator allows us to export an OMF2 file.”
Phillip Purcell: - Tracks
“We recently received an OMF file from a Version 9 Avid and the goal posts have changed again. It was different because Avid version 9 uses WAV files as it’s native audio file format because it is running on a PC - Windows NT platform. Nearly all our OMF files come from Avids running on Macs and the audio file format within the OMF file is AIFF. Fairlight suggested we get the AVID editor to convert the audio files to AIFF, which they can do quite easily. At present we still have problems trying to open OMF’s that contain WAV files. Even though Version 8 and 9 Avids use WAV as their native audio file format, when exporting the editor can select either WAV or AIFF format. We know AIFF works.”
Why does all source material have to be stripped with time code?
The importance of time code referenced source material can’t be emphasised enough. OMF file transfer is a thing of beauty when it works, but when it doesn’t work it can be a disaster with both editors and sound post crew pulling their hair out. There must always be a fallback position of the EDL and referenced source material for use in a conform session. With more documentaries and projects using multi-format non-time coded source material, DVC Pro, DVCAM, if the OMF doesn’t work this requires the audio post facility to have access to mulit-format playback decks, which many don’t have, and if they obtain a machine, the audio has to be manually re-sunk.
Phillip Purcell:
“It is very important that you have a reference EDL to fall back on if the OMF does not work. All source material must have been striped with time code. I would like to see the day when it isn’t necessary but at present you must have an EDL to fall back on if there are problems. The practice in a lot of boutique editing cottages of digitising material off DV tapes with out time code can create real problems if the OMF doesn’t work. The same goes for material digitised directly off CD. This is really not a good idea at the moment as it means you are totally dependent on your OMF file and if it doesn’t work you are really up the creek. You can’t even go back to the EDL because there isn’t one. These are the very jobs that have booked one day in the studio to do their mix and if you spend the first half of the day trying to open an OMF file with out success you’ve really blown it. You need to know that there is an EDL somewhere, there are time coded source reels somewhere, and if the OMF really doesn’t work you can make the decision to go back to the EDL and re-conform the project. The other point to mention is that the EDL also has to be readable. Today a lot people don’t spend any time sorting out their EDL because they assume the OMF will work. So you ring the picture edit suite for an EDL and you receive a disk that is unreadable, or the wrong format or missing half the edits you require. There was a time when EDLs were important and people would spend time to make sure that they would work.”
Simon Leadley:
“Before you even talk about the translations issues, you must discuss the day one issues, the procedures that are going to happen in the edit room. I want to use a piece of music. Don’t take it straight off a CD. First dub it to a DAT with time code, it now at least has a reference. If you are doing digital transfers they are all to be done at set sample rate and stick to it, 44.1kHz or 48kHz. The amount of time that can be wasted in sample rate conversion can be a real pain.”
What are some of the problems originated in the picture editing facility?
Simon Leadley:
“I have visited a lot of assistant editors digitising stations. They have twenty drives running right next to them, a pair of speakers about an inch tall, and one of the speakers doesn’t work or is blown. I recently visited a facility from where I had received an OMF. The visit was to confirm the audio quality out of the Avid. The audio on the workstation was completely distorted. Both tweeters in the speakers were blown. There was no option other than to go back and re-digitise all the audio. There has to be some one who has to say, if you go this route you cannot expect someone with little or no experience to deal with this. For the simple reason that this is stage one and you’re potentially carrying this audio to the end, being the final mix. What is worse is you receive the program right at the very end, you discover that there is a major problem that’s been there since day one and you have five minutes to solve it before it is to be delivered to the network broadcaster, or who ever. You can throw up your hands and say it is not my problem, and of course you know that never happens.
It is your problem and you have to deal with it. In the past we had full time transfer people who would look after the audio and transfers. That role has become part of the editing assistant’s duties. They should be given the tools to do their job properly. The assistant editors role is crucial. They can save you time, money and grief.”
Phillip Purcell:
“We tend to build up a relationship with the editor who digitises all material, edits, and creates the OMF file. Quite often we will go over to the edit suites and sit in with them while they create the OMF file.
The role of the editing assistant is really important. As we don’t use charts any more with DAWS, the naming and logging information on the audio clips that’s done by the assistant editor is extremely helpful. These same clips are transferred across through the OMF process. It’s incredibly useful as you can see what is coming up while you are mixing. When you go through EQing clips on the Fairlight and you see a clip, Joe Blogs at a certain location, and then discover you have just mixed and EQ’ed the same guy two scenes earlier. It is very easy for the mixer to copy that EQ curve on to all clips of the same name in that project. These picture workstations almost have to be audio mastering machines as the digitised audio created by them is used in final mix.”
How important will networks and the internet be in the future?
The ever-increasing use of networks and the Internet can be seen daily. Tele-streaming is currently being used by Cutting Edge in Brisbane to send program material for “Beastmasters” to Canada.
Mathew Wood, supervising sound editor for Phantom Menace recorded 1,500 lines of ADR on set in the UK into Protools on a modified G3 Powerbook, then sent the Protools session file over the Internet to Skywalker in the US. As bandwidth increases it is becoming more and more practical to send files across networks.
Digby Richards:
“The future with file transfer will be networks, where you can read the files straight off a server. Networks are going to be vital in the future. Not just local networks. With the expansion of bandwidth, you will be networking between buildings, cities, even internationally. You will also be networking between multi-platform machines. You will pull data live off a server and read it natively or translate it.”
Andrew Bell:
“In future you will see more workstations being online in regards to both the Internet and internal networks and that is where the real benefits of file transfer capability will be seen. Networking between multi platform workstations is being used today and will become an accepted practice, between audio and video. Turner Network Television in Hong Kong have a Fairlight Media Link server where different Avids export OMF1 files to the server and the Fairlight transfers the OMF1 file from the server directly onto it’s hard drives. Star TV in India is also networking Lightworks with Fairlights. Digital Post in Auckland, New Zealand has a PC sitting beside them in the studio which is networked with the Fairlight. With this PC they receive wave files from clients saying can you use this music or can you email me that voice take we recorded last week.”
Phillip Purcell:
“I would like to see it happen, but I imagine it would need everyone to have ISDN or fibre optic cabling. The idea of permanently moving hard drives and backup tapes around the place as we do now, is like the old 24 track tape days. With the advances in technology you would hope a faster way of file transfer would be possible. It would make sense to download OMF files over the net, even if it were over night. They would appear on your hard drive in the morning and you could open them straight away.”
Simon Leadley:
“Networking will be very important. For the past four years at Yoram Gross’s studio all of the projects have been done OMF over a network. The picture editors consolidate to a drive on the network somewhere away from the edit suite. The sound editor picks it up off the server on the network and translates the OMF file. It all works fine. At Soundfirm they have two servers on the network to transfer files. The other day I was working with one of the music editors on “Bootmen”. He needed access to a video clip. I went into the guys next door who are on the network, cut a 50 second clip from their material, created a new QuickTime file, sent it over the network, and he then imported it into his session here. It was done with no hassle with in ten minutes. If you had to go and get a dub of the scene or bring in a Beta SP it would have been a nightmare. Even in a mix session a director will want to change some thing. I will go to the edit suite change some thing and send the new file back across the network to the mix theatre. Simple. We also have a hard drive on the network which is dedicated specifically for sound effects. This just hangs off the server. I think you will see more and more networking between multi-platform machines. In regards to the Internet, when I was working on “Mission Impossible 2” we were sending video files across to America. These were compressed files, about 80Meg, and sent across via a cable modem. At Yoram Gross we send audio files back and forth to Canada via the net. With these dialogue files we usually compress them using MPEG and we can get something like 80Meg down to 10Meg.”
How could the OMF process be simplified?
OMF files are usually created by the editor at the end of a 12 to 13 hour day. The last thing they want to worry about is the extra work - consolidation, stripping of audiosuite effects, EQ, level, time compression, etc.
This maybe wishful thinking, but if the the next Avid software release could have another button on their “Create OMF” page which just says “export without audio effects” it would save a lot of time for the editors and reduce problems in sound post.
Another idea would be to establish a practice of including an OMF technical cover sheet to be filled out by the editors and delivered with the HDD or Jaz drives that hold the OMF files and contain the following information:
• Type of machine created on.
• Software version.
• NT or MAC.
• Type of OMF - 1 or 2.
• Sample rate.
• Exact name of the OMF file.
• Number of audio tracks in the OMF.
• T/C of first and last frame of audio, or T/C of Head and tail 2 pip.
• Name of operator who created the OMF and contact number.
The same procedure could take place including a text only file on the same hard drive on which the OMF file is delivered.
Phillip Purcell:
“The last thing an editor does at the end of his long day is to export the OMF files. Probably he or she really isn’t in the frame of mind to be worried about the fine details of exactly how to create the OMF file. Which buttons to click and which options to select. I think the more automated and more user friendly all that can be made, the better. Ideally this probably could be achieved through communication between both the picture and audio workstations manufacturers. Similar to a word processor, where you export as WordPerfect, Word7, etc.
In the Avid or Lightworks export menu you could have export as Protools, MFX, DSP, etc. The computer just does it. The picture editor doesn’t have to think about it. All the editor would have to do is click the name of the audio workstation, turn the lights off and walk out. At the moment the editor has to sits there agonising if they have named it the right way, or have they put too many dots or commas in the name, or selected the wrong audio format. If they are buggered at the end of the day, these issues are the last thing they want to worry about. We often come in the next morning and expect an OMF to open and it doesn’t because one of these parameters is wrong. What’s needed is a simple export software package that wraps up the OMF file.”
Where are we headed in the future?
With manufacturers constantly releasing new software and editors demanding more powerful applications, the need to export files processed by these applications arises. At present there are two new file interchange formats on the horizon. These are AAF and AES31.
• AFF (Advanced Authoring Format) is a proprietary format, which is being designed by Avid and Microsoft in conjunction with working group companies such as Adobe, Digidesign, Matrox, Pinnacle, SoftImage and others. Avid has licensed certain portions of its Open Media Framework Interchange format to the group as the core technology of the AAF format. The AAF format is said to provide powerful features to facilitate transfer of complex picture information, telecine pan and scan, colour grading information etc. AAF seems to be an extension of OMF2 and will carry both audio and video information.
• AES31 is an audio only file interchange standard, which will also hold audio editing information. A working group made up of members from the Audio Engineers Society developed AES31. The AES among other functions helps create international audio standards. They helped create other standards such as the AES11 standard, which is the standard AES/EBU audio input/output on digital equipment. Some of the companies involved in helping to create this standard were SSL, Fairlight, Akai, ADSG-Sony, and Sadie. The AES31 standard has been ratified and is already being implemented by Akai and Sadie.
The big difference between these two formats is that AAF is a proprietary format owned by Avid and Microsoft, while AES31 is a proposed international standard developed by an international standards organisation. In practice what this means is that once a standard has been established it is can be adopted by private companies to be incorporated into their products with out fear of change. Where as with a proprietary format, which is wholly owned by a company or companies, they can change the format at any time and in any way they like. As stated earlier both manufacturers and operators have been caught out in the past by new releases of Avid software where changes have been made which leave their devices unable to open OMF files. It begs the question will this also occur with AAF? And, of course, there will also be the point of licence fees to be addressed.
The other point to raise is even though AAF will be very powerful and offer extra vision capabilities, do sound post production people need this. Most audio practitioners I have spoken to simply want to get their audio across in one piece, and in sync. AES31 only carries audio and audio editing information. The decision as to which format will be embraced will, I am sure, be driven by which manufacturers choose to incorporate the format into their software.
Digby Richards:
“These conversion programs utilise a process which is known as computer parsing techniques. Very simply, imagine a piece of software trying to read an OMF file, if the format is simple, then it can read any file and it has got a pretty good idea of what to expect, so you have a pretty good chance that it won’t hiccup. With the OMF file you can put anything you like into it, and it’s not just the actual parameters that change, you can actually change the syntax. By doing this you can make the structures far more complex. This is why problems occur in OMF because the conversion program is reading files that the program has no idea how to deal with, files and commands it has never seen before.
At present our success is with OMF1 & 2, up to Avid Version 7.2, and OMF files from Lightworks. I approached Fairlight when we were working on Lightworks files, and to be perfectly honest I must say I found them very approachable and helpful, which was great. Given, we haven’t actually gone forward and done a direct DSP to Fairlight compatibility yet, but we would like to do in the future.
The one thing I am worried about with any new formats such as AAF and AES31 is open communication. With OMF at least they did have conferences and I at least knew who to email, and I was able to email quite regularly.”
Simon Leadley:
“I would have to be very skeptical about any of these new formats. I see new software occasionally and all they do is put lots of new features into it. What I’d like to see is a way of being able to get audio across really easily and to be able to incorporate changed lists into programs that have already been cut without problems. As far as I know with AAF they are going for the whole box and dice.
The MIDI format is probably the most successful standard that has ever been created. Every body adopted it and sure there were little hiccups at the beginning. Generally speaking you could get one piece of equipment and plug it into another piece of equipment and it would work predictably. To this day it has been with us for over ten years now in the same form that it was originally proposed. No other format has been as successful as that.
The way the Midi format was developed was by a group of manufacturers getting together and developing the specifications. The secret of the success of MIDI was that it was a completely open format. No one manufacturer owned it. With Avid they bastardised the OMF standard and didn’t adhere to their own standard when creating new products. This doesn’t help anyone and creates a lack of trust in the OMF process amongst operators.
Cross platform transfer of material has been successful in other areas. For instance you can create an ISO CD-ROM that can be read on nearly any machine. They have created a standard format.”
What other file transfer tools are being designed?
Over the past twelve months different manufactures having been developing stand alone conversion software packages to run on a host PC or Mac computer. Some of these manufacturers include:
• Digidesign with Digitranslator,
• Wave Frame,
• DSP with OMF Connect.
• AMS with Media Tool Box.
These software packages may become a regular feature in both picture and sound editing facilities.
Digby Richards:
”One new product we have released is a software package that translates from commonly used formats to other commonly used formats. This is a stand-alone package, called OMF Connect. So even if you are not a DSP facility you can utilise this package. This software was born out of the fact that we have our own converting utility at the moment that goes from OMF1 and OMF2 to the DSP format and vice versa. Until recently we have had a lot of success in being compatible with OMF systems. Soundfirm in Sydney are currently working on Moulin Rouge. They are using our software to successfully import Lightworks OMF files and export OMF files for Protools. In this situation the DSP is acting as a translator between Lightworks and Protools. The Lightworks files are converted into a DSP format and then exported out as an Akai dubber or a Protools format. There will always be a need to translate between these different formats.”
Simon Leadley:
“I think the Digitranslator would be very helpful if you were an Avid facility. They could create a Protools session and if they don’t get any errors they know it is right and it is done. Again if you were a DSP or Fairlight facility it would be helpful for translating files. I believe more people in the future will have a dedicated PC or Mac somewhere in the studio purely to handle file conversions.”
Will transfer of non-linear video file to sound post become standard?
The general consensus is that this is a way off yet. The reasons why can be seen in the comments below.
Digby Richards:
“Video is far more difficult to transfer than audio, as with video you are almost always dealing with compressed formats. Once you are dealing with compressed formats you are not dealing with software but rather hardware and chipsets that compressed it into that format. You can have JPEG cards that come from two different manufacturers and they won’t generate the same JPEG format. This is because some boards will only read a subset of the standard. There are a lot of parameters you can also change. You are also dealing with a lot more data. We have had a number of requests to offer the ability to both import and export video files.”
Phillip Purcell:
“It would be nice to able to get a non-linear video file with the OMF to work with since a lot of post people are already using non-linear pictures. At the end of a project you would be able to back up the video file with the project as with automation. Particularly because we are about to enter new Digital TV formats, wide screen, 16:9, HDTV, etc. If a project is originated in a set format it would be good to follow this format through to audio post.
Maybe non-linear video is a practical way of doing sound mixes in the future. Rather than having to get a reduction dub from high definition down to PAL standard television, as we most likely won’t be running high definition in sound post.”
Simon Leadley:
“The new version of Protools 5 can use the ABVB board, which the Avids use and can do up to AVR75. The idea is when they give you an OMF, they will give you a drive with all the media on it and the OMF would play back the vision that has been cut as well. Theoretically it means down the track if changes are made to the vision you just get an EDL and that conforms the program to the latest version including the audio. Personally, with most facilities in this country I can’t see it being a convincing thing to do yet. It is quite expensive. I think we are a way off from being able to have a standard video file format. At present an old Avid can’t even read a new Avid file. This is due to different file formats, resolutions, chipsets and compression. We are having enough problems with audio.”
And we haven’t even mentioned digital television video standards and MPEG2 video.
Conclusion:
I was planning on writing a summary paragraph but I think Simon best summed it up:
“I think the problem has been in the past that a lot the manufacturers were terrified of the opposition, and consequently, close relationships and communication between them in regards to standards did not take place. They really need to look at how the MIDI standard was developed. If you bought a MIDI device at the back of every manual it had the MIDI spec and told you what all the controllers did.
Every body benefited from that. There were no down sides.
This is what all the manufacturers need to understand.
By making varied workstations open to communicate with one another it means that suddenly there is true competition and you can talk about why our system is better than some one else’s. You are able to discuss the benefits like, this is a better editor because of this function. The end result is that you’re not locked in. You are able to work on some body else’s project created in another format. If I am working on Protools and some body else is doing their dialogue editing on a Fairlight, that should be of no consequence what so ever. We should easily be able to interchange our files.
Manufacturers have too much to loose if they don’t get involved in being able to freely exchange files. We are starting to get to that momentum point now where enough of them have jumped on board with this and are willing to release their computer codes that are required. It will be a case of, if you don’t jump on the bandwagon, you will be the one that misses out. We’ve seen this with open source code for computers. Microsoft has rigidly stood by and said we are not interested in doing that. Apple opened their code for many things. Linux is doing exceptionally well. People are saying, because we know what the source code is we can add on to these systems and create far more powerful applications. Through this process we are able to develop standards. The only way to develop a standard is if every body knows what that standard is. The moment you close ranks it is going to be a mess.”
I would like to propose that we establish a page on the ASSG website for sound post personal and facilities to post their own comments on this topic. Open lines of communication.
Thanks again to:-
Digby Richards from DSP
Andrew Bell from Fairlight
Simon Leadley from Trackdown Studios
Phillip Purcell from Tracks Television
If you would like to contact Tony and discuss any of the issues raised in this article, you can e-mail him at
tmurtagh@zip.com.au
Ever had a problem with an OMF or file interchange? Who hasn’t? Will we ever get to where we will not have to rely on the EDL conform? A mixing facility is faced with the problem of audio being delivered on multi-formats, dialogue on Fairlight, effects and foley on DSP and music on Protools.
How do they read all formats?
Will we ever be able to develop a reliable universal interchange format?
Wouldn’t it be nice if picture editing came after sound so they could experience all the problems sound post experience with OMF files that don’t work?
These are some of the points we will look at in this article.
It is always dangerous writing an article about areas that utilise constantly evolving computer technology. Almost by the time you have written the article the goal posts have changed again. What I will endeavour to do in this article is gain feedback from both manufacturers and operators who regularly have to deal with file format interchange issues.
My thanks to the following people for being so generous with their time and information.
From the manufacturers:
Andrew Bell from Fairlight
David (Digby) Richards from DSP
From the operators:
Simon Leadley from Trackdown Studios (OMF in feature films)
Phillip Purcell from Tracks Television (OMF in television).
What are the most common file formats used in audio?
• The first type of files are audio media only files, containing only the recorded audio clips. These formats include AIFF and AIFC (developed by Apple), WAV (developed by Microsoft), Broadcast WAV and a number of proprietary formats.
• The second type of file contains audio media and can include video, EDL, editing information and additional meta data. These formats include OMF1, OMF2, AAF, and AES31. Audio file formats commonly contained in the OMF format include AIFF or WAV. In future formats, such as AAF, there is mention of including extra complex picture information such as telecine “Pan & Scan” and colour grading notes, etc.
Why do we need a common interchange format?
• Saving of time (and hence money) by removing the need for EDL conforms.
• No more double handling of audio material and therefore less editing time.
• Transfer flexibility of product between different workstations.
• Ensure authenticity of authorship by receiving a project that is identical to the final cut created by the picture editor and director.
• Preserve quality by using all digital transfers. (If the digitising assistants know what they are doing!!!!!)
• Save time not having to dub all source material to time coded formats.
• Mixing facilities can receive audio from multi-platform workstations.
All these points are very beneficial in sound postproduction - if it all works!
Credit should be given to Avid for initiating the file interchange process with the OMF format.
What is required to interchange file formats?
File exchange between platforms relies on three completely independent pieces of technology.
• The first aspect is the disk format that contains the media.
A number of different disk file systems currently exists. Fat16, Fat32, NTFS, HFS (Mac), and a dozen or so proprietary systems are out there in the market place including Fairlight, Akai, etc. If you want to read a file created by some body else the first thing you have to do is be able to read the disk containing the media. Similarly if you want to send this media to another party you have to be able to write it to a disk format they can read.
• The second aspect is the audio file format, that is to say the file in which the audio is stored. WAV, Broadcast Wav, AIFF, AIFC, and again many proprietary ones.
For example, Fairlight is able to read Akai’s file format because Akai provided information about their file format, and Akai can read Fairlight files because they provided them with information about their file format.
AES31 uses the broadcast wave audio file format and uses Fat32 as its disk file format. OMF doesn’t mandate either of those things. It allows you to use any disk file system and any audio file format. This is one of the reasons why it becomes so complicated.
• The third aspect is the audio EDL format - the “Edit Decision List” format. In digital audio workstations these are proprietary files in each companies case. In Protools it is called a session file, in Fairlight a project, in Akai’s case an AKL file, in AES31 an ADL, in OMF it’s all part of the OMF file. These three areas must be examined and adhered to very closely.
Where are we at currently?
• Even in the OMF format, there is not one confirmed standard. At present, across Sydney studios, there is a mixture of OMF1 and OMF2 files being used. For Protools, with the release of the Digidesign’s Digitranslator, more and more OMF2 files are being utilised. Currently the ABC, Beyond, and Tracks Television all use OMF1 file transfers. Trackdown, Philmsound and Soundfirm (on the Farscape project) have been using OMF2 with a good success rate. Simon Leadley mentioned, that for the last 4 years, Yoram Gross Studios have used OMF1 and OMF2 on all of their television series projects with transfers from Avid to Protools. The use of these formats (OMF1 or 2) seems to be growing and gaining supporters along the way.
What are the problems reported with the OMF process?
Where to begin? Both manufacturers and operators have experienced a number of problems.
Manufacturers problems:
One of the problems experienced, centres around the varying versions of software release. As most OMF files are currently created on Avids, independent sound facilities are now expected to handle OMF files created on multiple versions of Avid software, rangeing from version 6, 7, 8, and now 9, either Mac or NT. Fairlight, DSP, Protools and AMS, all at one time or another, have been able to open OMF files successfully, then all of a sudden files won’t open. The cause? New Avid software version release!!!!! It is then up to the DAW manufacturers to play catch up with this new software release by modifying their software.
Digby Richards: - DSP
“When Avid were running Version 6.5 we were 100% compatible and every one thought it was wonderful. Then Avid Version 7 came out!
We didn’t change our software. We didn’t change a thing, but all of a sudden the files didn’t go across for various reasons. It’s easy to point the finger and say, it’s not our fault, but…. I understand both AMS and Fairlight also experienced similar problems. We think we are doing everything right. We have the published spec’s for OMF, we follow it completely, then something changes from someone else and it doesn’t work.
This has been the story with OMF and why there have been problems with the format.
I was at an OMF developers conference two years ago and the highlight of the week was a report from a feature film editor. He was to come in and tell us about his success with OMF. When he got up to speak, he eventually said OMF transfer was full of problems.”
Andrew Bell: - Fairlight
“I think what they’ve really changed are the bits of OMF that they’re implementing. OMF contains features that are not universal to the audio industry. So if a particular company uses those features they may not be able to translate their audio into another format, or rather somebody else may not be able to get it out of the OMF format, as in group clips and sub clips. OMF also allows you to use any sort of processing you like.
In theory you’re supposed to define what this is, but that’s not really possible. This is processing that takes place in real time on the audio. For example there is a thing called a group object and you can specify any algorithm you would like to operate on that group. So the algorithm might mix them all together or it might play only the one with the most recent date on it. There are options and they are not specified by OMF. OMF just says you can add your own effect here. That is one of the biggest problems.”
TM: Should the specifications for OMF be more stringent?
Andrew Bell:
“Well there are arguments on both sides. You could say, lets reduce it to the most reasonable common denominator of features that most workstations have. This would result in a better success rate, but you would have people saying, well I want to do more on my workstation before I transfer it across. I don’t want to render all that to the audio because I want the next guy down the line to have the ability to unpick it if he wants to. This precise argument was expounded in great detail during the AES31 development. Now that’s the other side of the coin in most respects. It’s not sponsored or owned by one company. It’s not subject to anybody’s contractual control. It’s simply a standard that’s been created now and ratified.”
Operator problems experienced using OMFI:
• Varying versions of Avid software.
• Sub clips and group clips, used with multi-camera coverage.
• Audio media imported correctly but out of sync by 1 frame.
• Different sample rates: 44.1 or 48. If a post facility is clocked digitally to a set sample rate and an OMF arrives at a different sample rate problems arise.
• Audio digitised in “Draft” mode at 22 kHz.
• Incorrect Consolidation, not stripping off all Audiosuite effects, EQ, fades, level control, rubber banding, time compression, plug ins.
• Leaving extensions off a file name. (.OMF)
• Only 1 audio track digitised in.
• L+R summed to mono,
• Level too high (distorted), level too low (hissy).
• Audio media is off line.
• Formatting of the hard drive on to which the OMF is transferred is incompatible.
• Audio OMF files being transferred between different versions of Avid before being finally OMF’ed to Audio. (Offline Avid 6.5 to Online Avid 7.)
• Non time-code source tapes, if conform required.
I am sure there are many more. Many of these problems can be solved in the picture edit suite before the OMF is created. (continued next month.)
Operator comments:
Simon Leadley: - Trackdown
“OMF files will be received that have been created on very early versions of Avids which will only create OMF1 files. This means I have to keep versions of OMF tools, the first version being quite buggy, and this general means I have to supervise and keep a close eye on the conversion. It is essential that who ever is going to do the audio insists they go over to picture post and check the OMF process. Firstly they must check that the source material coming out of the Avid is OK before they even bother to make an OMF. Then the second thing is to go through the whole OMF process. I have virtually had to learn how to use the Avid in order to be able to assure that I could receive a useable OMF file. At the end of the day, to me, this is an area where I feel picture editors should be very comfortable with and understand how it works. However the process of creating the OMF file kind of falls between the cracks, in terms of whose responsibility it is. It’s like delivering the master tape to somebody in a way.
There was a film that took place recently and it took them two weeks to get the OMF to work. By this stage I think one of the guys had gone bald and the other guy had turned totally grey trying to get these files to open. I wasn’t directly involved, but after examining the files we discovered that not one single audio file referenced to this particular session existed on the hard drive they sent over. So in the OMF translation the program was looking for audio media that simply wasn’t there. The editor had done a consolidation, but completely not understood what a consolidation meant.
They had consolidated the project and then copied the wrong media files across. As there was a fundamental misunderstanding every time they created a new OMF, they made the same error. This is partly a problem in the way the Avid works. On one level it is very unfriendly to explain to you what’s going on because it tries to hide all the difficulties from you. For example you get an Avid file called AEDECB_EFGBA, you can’t tell easily what that means in a session. However in Protools it is a different story. (And Avid own Pro-Tools) They expect you to fiddle around with the files at the finder level and you know what is going on. Finally once we figured out what was going on with the OMF file it worked first go. This poor guy was going absolutely nuts. The problem was totally down to people who didn’t know what they were doing.
There are certain things you have to be aware of like deleting fade files, making sure there are not group clips in multi-cam shoots, whether the editor consolidates the files correctly and they understand exactly what the consolidation process does, that they completely understand what they are trying to do. Any one of those things you don’t understand will lead to an OMF that doesn’t work. What happens is, you receive a hard drive, a zip, or what ever from some body, but you can’t be absolutely sure how they have created that file. Is it an OMF1, is it an OMF2, what version of software, unless they have specially written down what it is, or given you a hint with the name they have called the file. Basically you sit there with every tool you’ve got and try and open this file.
Most of the OMF files we have received lately have been in the OMF2 format. The OMF2 files seem to work a little bit better at the moment. I think OMF2 is the way things are headed, and this can be seen by the new Digitranslator from Digidesign for Protools. The Digitranslator will only work with OMF2 files and not OMF1. This was pointed out to Digidesign and the reason they gave for only supporting OMF2 was because OMF2 had better specification than OMF1. In practice it was felt OMF2 was less buggy than OMF1. Digitranslator allows us to export an OMF2 file.”
Phillip Purcell: - Tracks
“We recently received an OMF file from a Version 9 Avid and the goal posts have changed again. It was different because Avid version 9 uses WAV files as it’s native audio file format because it is running on a PC - Windows NT platform. Nearly all our OMF files come from Avids running on Macs and the audio file format within the OMF file is AIFF. Fairlight suggested we get the AVID editor to convert the audio files to AIFF, which they can do quite easily. At present we still have problems trying to open OMF’s that contain WAV files. Even though Version 8 and 9 Avids use WAV as their native audio file format, when exporting the editor can select either WAV or AIFF format. We know AIFF works.”
Why does all source material have to be stripped with time code?
The importance of time code referenced source material can’t be emphasised enough. OMF file transfer is a thing of beauty when it works, but when it doesn’t work it can be a disaster with both editors and sound post crew pulling their hair out. There must always be a fallback position of the EDL and referenced source material for use in a conform session. With more documentaries and projects using multi-format non-time coded source material, DVC Pro, DVCAM, if the OMF doesn’t work this requires the audio post facility to have access to mulit-format playback decks, which many don’t have, and if they obtain a machine, the audio has to be manually re-sunk.
Phillip Purcell:
“It is very important that you have a reference EDL to fall back on if the OMF does not work. All source material must have been striped with time code. I would like to see the day when it isn’t necessary but at present you must have an EDL to fall back on if there are problems. The practice in a lot of boutique editing cottages of digitising material off DV tapes with out time code can create real problems if the OMF doesn’t work. The same goes for material digitised directly off CD. This is really not a good idea at the moment as it means you are totally dependent on your OMF file and if it doesn’t work you are really up the creek. You can’t even go back to the EDL because there isn’t one. These are the very jobs that have booked one day in the studio to do their mix and if you spend the first half of the day trying to open an OMF file with out success you’ve really blown it. You need to know that there is an EDL somewhere, there are time coded source reels somewhere, and if the OMF really doesn’t work you can make the decision to go back to the EDL and re-conform the project. The other point to mention is that the EDL also has to be readable. Today a lot people don’t spend any time sorting out their EDL because they assume the OMF will work. So you ring the picture edit suite for an EDL and you receive a disk that is unreadable, or the wrong format or missing half the edits you require. There was a time when EDLs were important and people would spend time to make sure that they would work.”
Simon Leadley:
“Before you even talk about the translations issues, you must discuss the day one issues, the procedures that are going to happen in the edit room. I want to use a piece of music. Don’t take it straight off a CD. First dub it to a DAT with time code, it now at least has a reference. If you are doing digital transfers they are all to be done at set sample rate and stick to it, 44.1kHz or 48kHz. The amount of time that can be wasted in sample rate conversion can be a real pain.”
What are some of the problems originated in the picture editing facility?
Simon Leadley:
“I have visited a lot of assistant editors digitising stations. They have twenty drives running right next to them, a pair of speakers about an inch tall, and one of the speakers doesn’t work or is blown. I recently visited a facility from where I had received an OMF. The visit was to confirm the audio quality out of the Avid. The audio on the workstation was completely distorted. Both tweeters in the speakers were blown. There was no option other than to go back and re-digitise all the audio. There has to be some one who has to say, if you go this route you cannot expect someone with little or no experience to deal with this. For the simple reason that this is stage one and you’re potentially carrying this audio to the end, being the final mix. What is worse is you receive the program right at the very end, you discover that there is a major problem that’s been there since day one and you have five minutes to solve it before it is to be delivered to the network broadcaster, or who ever. You can throw up your hands and say it is not my problem, and of course you know that never happens.
It is your problem and you have to deal with it. In the past we had full time transfer people who would look after the audio and transfers. That role has become part of the editing assistant’s duties. They should be given the tools to do their job properly. The assistant editors role is crucial. They can save you time, money and grief.”
Phillip Purcell:
“We tend to build up a relationship with the editor who digitises all material, edits, and creates the OMF file. Quite often we will go over to the edit suites and sit in with them while they create the OMF file.
The role of the editing assistant is really important. As we don’t use charts any more with DAWS, the naming and logging information on the audio clips that’s done by the assistant editor is extremely helpful. These same clips are transferred across through the OMF process. It’s incredibly useful as you can see what is coming up while you are mixing. When you go through EQing clips on the Fairlight and you see a clip, Joe Blogs at a certain location, and then discover you have just mixed and EQ’ed the same guy two scenes earlier. It is very easy for the mixer to copy that EQ curve on to all clips of the same name in that project. These picture workstations almost have to be audio mastering machines as the digitised audio created by them is used in final mix.”
How important will networks and the internet be in the future?
The ever-increasing use of networks and the Internet can be seen daily. Tele-streaming is currently being used by Cutting Edge in Brisbane to send program material for “Beastmasters” to Canada.
Mathew Wood, supervising sound editor for Phantom Menace recorded 1,500 lines of ADR on set in the UK into Protools on a modified G3 Powerbook, then sent the Protools session file over the Internet to Skywalker in the US. As bandwidth increases it is becoming more and more practical to send files across networks.
Digby Richards:
“The future with file transfer will be networks, where you can read the files straight off a server. Networks are going to be vital in the future. Not just local networks. With the expansion of bandwidth, you will be networking between buildings, cities, even internationally. You will also be networking between multi-platform machines. You will pull data live off a server and read it natively or translate it.”
Andrew Bell:
“In future you will see more workstations being online in regards to both the Internet and internal networks and that is where the real benefits of file transfer capability will be seen. Networking between multi platform workstations is being used today and will become an accepted practice, between audio and video. Turner Network Television in Hong Kong have a Fairlight Media Link server where different Avids export OMF1 files to the server and the Fairlight transfers the OMF1 file from the server directly onto it’s hard drives. Star TV in India is also networking Lightworks with Fairlights. Digital Post in Auckland, New Zealand has a PC sitting beside them in the studio which is networked with the Fairlight. With this PC they receive wave files from clients saying can you use this music or can you email me that voice take we recorded last week.”
Phillip Purcell:
“I would like to see it happen, but I imagine it would need everyone to have ISDN or fibre optic cabling. The idea of permanently moving hard drives and backup tapes around the place as we do now, is like the old 24 track tape days. With the advances in technology you would hope a faster way of file transfer would be possible. It would make sense to download OMF files over the net, even if it were over night. They would appear on your hard drive in the morning and you could open them straight away.”
Simon Leadley:
“Networking will be very important. For the past four years at Yoram Gross’s studio all of the projects have been done OMF over a network. The picture editors consolidate to a drive on the network somewhere away from the edit suite. The sound editor picks it up off the server on the network and translates the OMF file. It all works fine. At Soundfirm they have two servers on the network to transfer files. The other day I was working with one of the music editors on “Bootmen”. He needed access to a video clip. I went into the guys next door who are on the network, cut a 50 second clip from their material, created a new QuickTime file, sent it over the network, and he then imported it into his session here. It was done with no hassle with in ten minutes. If you had to go and get a dub of the scene or bring in a Beta SP it would have been a nightmare. Even in a mix session a director will want to change some thing. I will go to the edit suite change some thing and send the new file back across the network to the mix theatre. Simple. We also have a hard drive on the network which is dedicated specifically for sound effects. This just hangs off the server. I think you will see more and more networking between multi-platform machines. In regards to the Internet, when I was working on “Mission Impossible 2” we were sending video files across to America. These were compressed files, about 80Meg, and sent across via a cable modem. At Yoram Gross we send audio files back and forth to Canada via the net. With these dialogue files we usually compress them using MPEG and we can get something like 80Meg down to 10Meg.”
How could the OMF process be simplified?
OMF files are usually created by the editor at the end of a 12 to 13 hour day. The last thing they want to worry about is the extra work - consolidation, stripping of audiosuite effects, EQ, level, time compression, etc.
This maybe wishful thinking, but if the the next Avid software release could have another button on their “Create OMF” page which just says “export without audio effects” it would save a lot of time for the editors and reduce problems in sound post.
Another idea would be to establish a practice of including an OMF technical cover sheet to be filled out by the editors and delivered with the HDD or Jaz drives that hold the OMF files and contain the following information:
• Type of machine created on.
• Software version.
• NT or MAC.
• Type of OMF - 1 or 2.
• Sample rate.
• Exact name of the OMF file.
• Number of audio tracks in the OMF.
• T/C of first and last frame of audio, or T/C of Head and tail 2 pip.
• Name of operator who created the OMF and contact number.
The same procedure could take place including a text only file on the same hard drive on which the OMF file is delivered.
Phillip Purcell:
“The last thing an editor does at the end of his long day is to export the OMF files. Probably he or she really isn’t in the frame of mind to be worried about the fine details of exactly how to create the OMF file. Which buttons to click and which options to select. I think the more automated and more user friendly all that can be made, the better. Ideally this probably could be achieved through communication between both the picture and audio workstations manufacturers. Similar to a word processor, where you export as WordPerfect, Word7, etc.
In the Avid or Lightworks export menu you could have export as Protools, MFX, DSP, etc. The computer just does it. The picture editor doesn’t have to think about it. All the editor would have to do is click the name of the audio workstation, turn the lights off and walk out. At the moment the editor has to sits there agonising if they have named it the right way, or have they put too many dots or commas in the name, or selected the wrong audio format. If they are buggered at the end of the day, these issues are the last thing they want to worry about. We often come in the next morning and expect an OMF to open and it doesn’t because one of these parameters is wrong. What’s needed is a simple export software package that wraps up the OMF file.”
Where are we headed in the future?
With manufacturers constantly releasing new software and editors demanding more powerful applications, the need to export files processed by these applications arises. At present there are two new file interchange formats on the horizon. These are AAF and AES31.
• AFF (Advanced Authoring Format) is a proprietary format, which is being designed by Avid and Microsoft in conjunction with working group companies such as Adobe, Digidesign, Matrox, Pinnacle, SoftImage and others. Avid has licensed certain portions of its Open Media Framework Interchange format to the group as the core technology of the AAF format. The AAF format is said to provide powerful features to facilitate transfer of complex picture information, telecine pan and scan, colour grading information etc. AAF seems to be an extension of OMF2 and will carry both audio and video information.
• AES31 is an audio only file interchange standard, which will also hold audio editing information. A working group made up of members from the Audio Engineers Society developed AES31. The AES among other functions helps create international audio standards. They helped create other standards such as the AES11 standard, which is the standard AES/EBU audio input/output on digital equipment. Some of the companies involved in helping to create this standard were SSL, Fairlight, Akai, ADSG-Sony, and Sadie. The AES31 standard has been ratified and is already being implemented by Akai and Sadie.
The big difference between these two formats is that AAF is a proprietary format owned by Avid and Microsoft, while AES31 is a proposed international standard developed by an international standards organisation. In practice what this means is that once a standard has been established it is can be adopted by private companies to be incorporated into their products with out fear of change. Where as with a proprietary format, which is wholly owned by a company or companies, they can change the format at any time and in any way they like. As stated earlier both manufacturers and operators have been caught out in the past by new releases of Avid software where changes have been made which leave their devices unable to open OMF files. It begs the question will this also occur with AAF? And, of course, there will also be the point of licence fees to be addressed.
The other point to raise is even though AAF will be very powerful and offer extra vision capabilities, do sound post production people need this. Most audio practitioners I have spoken to simply want to get their audio across in one piece, and in sync. AES31 only carries audio and audio editing information. The decision as to which format will be embraced will, I am sure, be driven by which manufacturers choose to incorporate the format into their software.
Digby Richards:
“These conversion programs utilise a process which is known as computer parsing techniques. Very simply, imagine a piece of software trying to read an OMF file, if the format is simple, then it can read any file and it has got a pretty good idea of what to expect, so you have a pretty good chance that it won’t hiccup. With the OMF file you can put anything you like into it, and it’s not just the actual parameters that change, you can actually change the syntax. By doing this you can make the structures far more complex. This is why problems occur in OMF because the conversion program is reading files that the program has no idea how to deal with, files and commands it has never seen before.
At present our success is with OMF1 & 2, up to Avid Version 7.2, and OMF files from Lightworks. I approached Fairlight when we were working on Lightworks files, and to be perfectly honest I must say I found them very approachable and helpful, which was great. Given, we haven’t actually gone forward and done a direct DSP to Fairlight compatibility yet, but we would like to do in the future.
The one thing I am worried about with any new formats such as AAF and AES31 is open communication. With OMF at least they did have conferences and I at least knew who to email, and I was able to email quite regularly.”
Simon Leadley:
“I would have to be very skeptical about any of these new formats. I see new software occasionally and all they do is put lots of new features into it. What I’d like to see is a way of being able to get audio across really easily and to be able to incorporate changed lists into programs that have already been cut without problems. As far as I know with AAF they are going for the whole box and dice.
The MIDI format is probably the most successful standard that has ever been created. Every body adopted it and sure there were little hiccups at the beginning. Generally speaking you could get one piece of equipment and plug it into another piece of equipment and it would work predictably. To this day it has been with us for over ten years now in the same form that it was originally proposed. No other format has been as successful as that.
The way the Midi format was developed was by a group of manufacturers getting together and developing the specifications. The secret of the success of MIDI was that it was a completely open format. No one manufacturer owned it. With Avid they bastardised the OMF standard and didn’t adhere to their own standard when creating new products. This doesn’t help anyone and creates a lack of trust in the OMF process amongst operators.
Cross platform transfer of material has been successful in other areas. For instance you can create an ISO CD-ROM that can be read on nearly any machine. They have created a standard format.”
What other file transfer tools are being designed?
Over the past twelve months different manufactures having been developing stand alone conversion software packages to run on a host PC or Mac computer. Some of these manufacturers include:
• Digidesign with Digitranslator,
• Wave Frame,
• DSP with OMF Connect.
• AMS with Media Tool Box.
These software packages may become a regular feature in both picture and sound editing facilities.
Digby Richards:
”One new product we have released is a software package that translates from commonly used formats to other commonly used formats. This is a stand-alone package, called OMF Connect. So even if you are not a DSP facility you can utilise this package. This software was born out of the fact that we have our own converting utility at the moment that goes from OMF1 and OMF2 to the DSP format and vice versa. Until recently we have had a lot of success in being compatible with OMF systems. Soundfirm in Sydney are currently working on Moulin Rouge. They are using our software to successfully import Lightworks OMF files and export OMF files for Protools. In this situation the DSP is acting as a translator between Lightworks and Protools. The Lightworks files are converted into a DSP format and then exported out as an Akai dubber or a Protools format. There will always be a need to translate between these different formats.”
Simon Leadley:
“I think the Digitranslator would be very helpful if you were an Avid facility. They could create a Protools session and if they don’t get any errors they know it is right and it is done. Again if you were a DSP or Fairlight facility it would be helpful for translating files. I believe more people in the future will have a dedicated PC or Mac somewhere in the studio purely to handle file conversions.”
Will transfer of non-linear video file to sound post become standard?
The general consensus is that this is a way off yet. The reasons why can be seen in the comments below.
Digby Richards:
“Video is far more difficult to transfer than audio, as with video you are almost always dealing with compressed formats. Once you are dealing with compressed formats you are not dealing with software but rather hardware and chipsets that compressed it into that format. You can have JPEG cards that come from two different manufacturers and they won’t generate the same JPEG format. This is because some boards will only read a subset of the standard. There are a lot of parameters you can also change. You are also dealing with a lot more data. We have had a number of requests to offer the ability to both import and export video files.”
Phillip Purcell:
“It would be nice to able to get a non-linear video file with the OMF to work with since a lot of post people are already using non-linear pictures. At the end of a project you would be able to back up the video file with the project as with automation. Particularly because we are about to enter new Digital TV formats, wide screen, 16:9, HDTV, etc. If a project is originated in a set format it would be good to follow this format through to audio post.
Maybe non-linear video is a practical way of doing sound mixes in the future. Rather than having to get a reduction dub from high definition down to PAL standard television, as we most likely won’t be running high definition in sound post.”
Simon Leadley:
“The new version of Protools 5 can use the ABVB board, which the Avids use and can do up to AVR75. The idea is when they give you an OMF, they will give you a drive with all the media on it and the OMF would play back the vision that has been cut as well. Theoretically it means down the track if changes are made to the vision you just get an EDL and that conforms the program to the latest version including the audio. Personally, with most facilities in this country I can’t see it being a convincing thing to do yet. It is quite expensive. I think we are a way off from being able to have a standard video file format. At present an old Avid can’t even read a new Avid file. This is due to different file formats, resolutions, chipsets and compression. We are having enough problems with audio.”
And we haven’t even mentioned digital television video standards and MPEG2 video.
Conclusion:
I was planning on writing a summary paragraph but I think Simon best summed it up:
“I think the problem has been in the past that a lot the manufacturers were terrified of the opposition, and consequently, close relationships and communication between them in regards to standards did not take place. They really need to look at how the MIDI standard was developed. If you bought a MIDI device at the back of every manual it had the MIDI spec and told you what all the controllers did.
Every body benefited from that. There were no down sides.
This is what all the manufacturers need to understand.
By making varied workstations open to communicate with one another it means that suddenly there is true competition and you can talk about why our system is better than some one else’s. You are able to discuss the benefits like, this is a better editor because of this function. The end result is that you’re not locked in. You are able to work on some body else’s project created in another format. If I am working on Protools and some body else is doing their dialogue editing on a Fairlight, that should be of no consequence what so ever. We should easily be able to interchange our files.
Manufacturers have too much to loose if they don’t get involved in being able to freely exchange files. We are starting to get to that momentum point now where enough of them have jumped on board with this and are willing to release their computer codes that are required. It will be a case of, if you don’t jump on the bandwagon, you will be the one that misses out. We’ve seen this with open source code for computers. Microsoft has rigidly stood by and said we are not interested in doing that. Apple opened their code for many things. Linux is doing exceptionally well. People are saying, because we know what the source code is we can add on to these systems and create far more powerful applications. Through this process we are able to develop standards. The only way to develop a standard is if every body knows what that standard is. The moment you close ranks it is going to be a mess.”
I would like to propose that we establish a page on the ASSG website for sound post personal and facilities to post their own comments on this topic. Open lines of communication.
Thanks again to:-
Digby Richards from DSP
Andrew Bell from Fairlight
Simon Leadley from Trackdown Studios
Phillip Purcell from Tracks Television
If you would like to contact Tony and discuss any of the issues raised in this article, you can e-mail him at
tmurtagh@zip.com.au