Archive
11-02-2003, 12:08 AM
Matthew's 1996 article still applies today ...
WHAT IS BROADCAST QUALITY?
"Its no use recording a master tape that looks the bees knees if all the audience will ever see is the dog's breakfast."
Broadcast Quality is not an optional extra. It is simply the minimum quality you should accept.
From an objective technical standpoint, a program can be defined as being of Broadcast Quality when it can be transmitted using conventional analogue TV transmitters without distortion or artifact. In other words, what the consumer sees at home is what the filmmaker intended. This may sound simple and straightforward, and it is, but you have to be aware of some of the limitations on the processes of TV transmission.
A chain is only as strong as its weakest link, and in TV technology the weakest link is arguably the composite transmission systems used worldwide. These systems were initially set up to enable transmission of pictures and sounds within a certain fixed and narrow bandwidth. The advent of component and digital video technology has brought vast improvements to image quality and resolution, but such is the huge investment in composite transmission infrastructure that it will be quite some time, if ever, that television transmission as we know it will catch up. Hence it is the limiting factor in the chain, the narrowest data pipe.
Effectively, this means that no matter how sophisticated or expensive the postproduction process, if the end result does not fall within the ability of the transmission system to broadcast it, the consumer will NOT see the program as it was intended. This is what specifications are all about - a set of rules dealing with colour, luminance, timing etc that describe the television system within which programs will be broadcast.
The first videotape machines were, sensibly, designed specifically to record these signals, and pushing the signals on the tape much beyond the intended limits caused all sorts of problems such as flare, jitter, colourshifts, dropout etc.
As videotape technology progressed, the capacity to record better and clearer signals increased ... remember the huge leap from Umatic to SP Betacam? Now, digital technology is omnipresent, and videotape recordings are no longer constrained by the limits of transmission technology. On a digital tape you can record images with a far greater contrast, colour depth and resolution than ever before, and many of the failings of analogue videotape such as dropouts and noise are largely a thing of the past. Videotape soundtracks are now "CD quality" with the capacity for enormous dynamic range and subtlety. Its all so exciting I just fell off my stool.
HOWEVER ... the weakest link is still there, and that's the trap! Its no use recording a master tape that looks the bees knees if all the audience will ever see is the dog's breakfast. If a digital master tape is not kept within transmission spec, all that beautiful saturated colour will just smudge into itself on the home telly. Those rich crushed blacks will overload the transmitter unless they are flattened out, and those crisp white details could cause the transmitter to dropout unless they are removed.
So, as a matter of course, TV stations use a device called a Proc Amp (processing amplifier) just before the transmitter to remove the offending bits that it just can't cope with, bits that it cannot squeeze down its narrow analogue pipe.
But hey, those are the bits that gave your program that lovely look in the digital suite! Your lovely contrasty shadows just got flattened and the logo looks different. Your subtle atmos tracks are inaudible and the dialogue just doesn't cut through. What's going on? What can you do about it?
Well, I think the most sensible approach is to realise the limitations of each stage of post. By all means, use the new digital supports to capture and process the subtleties. Use the high signal/noise and freedom from dropouts to make the cleanest of keys and the most complex multilayering. Use the digital tools to fine tune the image and tweak the gamma curves. Sure, there are a whole different set of digital specs that you can use, PROVIDED THAT you stay in the digital domain, such as if your program will be delivered in the new DVD format.
But then, accept the challenge of making a program master that will look good outside the online suite. This means keeping it within the limitations of the transmitter and the ability of the consumer telly to display the result. Its as useful looking at everything on a component or digital monitor as it is doing a TV mix in a sensurround theatre. Mum just won't see it like that at home, and that's what really counts, isn't it?
It appears as if, to a lot of people, making a broadcast quality master is a costly and onerous task to discharge. It need not be so ... most problems are simply a result of individuals being unaware of the limitations in the process. And it does get onerous when those problems have to be repaired at a later stage or as a result of a "rejection".
Make it quite clear to your online facility the standards you require. If your requirements are clearly defined to begin with then you should not have to pay more to do "repairs" if necessary later on.
A Collection of BS
If you are told that meeting broadcast specifications will cost more then that's just crap, go elsewhere. Broadcast Quality is not an optional extra. It is simply the minimum quality you should accept.
"It contains archival material so it can't/doesn't have to meet broadcast spec."
BS. Even if the original material was not within spec, it can always be brought within spec on the master. And so what if it looks archival? (Unless of course you are pretending its NOT - then you have to do clever tricks.)
"It was shot on HI-8 so it can't/doesn't have to meet broadcast spec."
More BS. Once transferred to your master, it can easily be brought up to scratch. It may still look like Hi-8 - all noisy and weird colours and shaky - but unless you are trying to pretend that its Panavision it can be perfectly acceptable.
"Its not going to be broadcast so it doesn't have to meet broadcast spec."
In my opinion, still more BS. Why accept second rate for anything? The specifications quite adequately describe the limitations of most common videocassette formats as well as transmission. You never know whether one day someone will want to transmit your program. Remember, Broadcast Quality is not an optional extra. It is simply the minimum quality you should accept.
"We put stuff out like this all the time and no-one complains"
Read that line again and consider whether you really need that attitude?
"Soon, TV stations will all be transmitting D1 anyway, so ... etc,"
My Giddy Aunt! I don't believe I heard that! D1 is around 270MBits/sec. Cable maybe, but not television, not soon!
It could be argued that when you hook up to Foxtus and get your 3D-interactive-virtual- reality-television-on-demand piped down an optical fibre into your toaster then that will be true digital transmission and hence independent of those demon "specs" - but that would only really be true if you junked your old telly (and toaster) and hooked up a new digital set. And then, in order that you can download your Barry Manilow CDs from the internet, whilst watching Terminator and The Piano simultaneously, those images would have to be heavily compressed anyway. And compression relies on knowing what is black and what is white and what can be expected in between. And thats what the specs are for.
Read the Followup!
- Matthew Tucker
WHAT IS BROADCAST QUALITY?
"Its no use recording a master tape that looks the bees knees if all the audience will ever see is the dog's breakfast."
Broadcast Quality is not an optional extra. It is simply the minimum quality you should accept.
From an objective technical standpoint, a program can be defined as being of Broadcast Quality when it can be transmitted using conventional analogue TV transmitters without distortion or artifact. In other words, what the consumer sees at home is what the filmmaker intended. This may sound simple and straightforward, and it is, but you have to be aware of some of the limitations on the processes of TV transmission.
A chain is only as strong as its weakest link, and in TV technology the weakest link is arguably the composite transmission systems used worldwide. These systems were initially set up to enable transmission of pictures and sounds within a certain fixed and narrow bandwidth. The advent of component and digital video technology has brought vast improvements to image quality and resolution, but such is the huge investment in composite transmission infrastructure that it will be quite some time, if ever, that television transmission as we know it will catch up. Hence it is the limiting factor in the chain, the narrowest data pipe.
Effectively, this means that no matter how sophisticated or expensive the postproduction process, if the end result does not fall within the ability of the transmission system to broadcast it, the consumer will NOT see the program as it was intended. This is what specifications are all about - a set of rules dealing with colour, luminance, timing etc that describe the television system within which programs will be broadcast.
The first videotape machines were, sensibly, designed specifically to record these signals, and pushing the signals on the tape much beyond the intended limits caused all sorts of problems such as flare, jitter, colourshifts, dropout etc.
As videotape technology progressed, the capacity to record better and clearer signals increased ... remember the huge leap from Umatic to SP Betacam? Now, digital technology is omnipresent, and videotape recordings are no longer constrained by the limits of transmission technology. On a digital tape you can record images with a far greater contrast, colour depth and resolution than ever before, and many of the failings of analogue videotape such as dropouts and noise are largely a thing of the past. Videotape soundtracks are now "CD quality" with the capacity for enormous dynamic range and subtlety. Its all so exciting I just fell off my stool.
HOWEVER ... the weakest link is still there, and that's the trap! Its no use recording a master tape that looks the bees knees if all the audience will ever see is the dog's breakfast. If a digital master tape is not kept within transmission spec, all that beautiful saturated colour will just smudge into itself on the home telly. Those rich crushed blacks will overload the transmitter unless they are flattened out, and those crisp white details could cause the transmitter to dropout unless they are removed.
So, as a matter of course, TV stations use a device called a Proc Amp (processing amplifier) just before the transmitter to remove the offending bits that it just can't cope with, bits that it cannot squeeze down its narrow analogue pipe.
But hey, those are the bits that gave your program that lovely look in the digital suite! Your lovely contrasty shadows just got flattened and the logo looks different. Your subtle atmos tracks are inaudible and the dialogue just doesn't cut through. What's going on? What can you do about it?
Well, I think the most sensible approach is to realise the limitations of each stage of post. By all means, use the new digital supports to capture and process the subtleties. Use the high signal/noise and freedom from dropouts to make the cleanest of keys and the most complex multilayering. Use the digital tools to fine tune the image and tweak the gamma curves. Sure, there are a whole different set of digital specs that you can use, PROVIDED THAT you stay in the digital domain, such as if your program will be delivered in the new DVD format.
But then, accept the challenge of making a program master that will look good outside the online suite. This means keeping it within the limitations of the transmitter and the ability of the consumer telly to display the result. Its as useful looking at everything on a component or digital monitor as it is doing a TV mix in a sensurround theatre. Mum just won't see it like that at home, and that's what really counts, isn't it?
It appears as if, to a lot of people, making a broadcast quality master is a costly and onerous task to discharge. It need not be so ... most problems are simply a result of individuals being unaware of the limitations in the process. And it does get onerous when those problems have to be repaired at a later stage or as a result of a "rejection".
Make it quite clear to your online facility the standards you require. If your requirements are clearly defined to begin with then you should not have to pay more to do "repairs" if necessary later on.
A Collection of BS
If you are told that meeting broadcast specifications will cost more then that's just crap, go elsewhere. Broadcast Quality is not an optional extra. It is simply the minimum quality you should accept.
"It contains archival material so it can't/doesn't have to meet broadcast spec."
BS. Even if the original material was not within spec, it can always be brought within spec on the master. And so what if it looks archival? (Unless of course you are pretending its NOT - then you have to do clever tricks.)
"It was shot on HI-8 so it can't/doesn't have to meet broadcast spec."
More BS. Once transferred to your master, it can easily be brought up to scratch. It may still look like Hi-8 - all noisy and weird colours and shaky - but unless you are trying to pretend that its Panavision it can be perfectly acceptable.
"Its not going to be broadcast so it doesn't have to meet broadcast spec."
In my opinion, still more BS. Why accept second rate for anything? The specifications quite adequately describe the limitations of most common videocassette formats as well as transmission. You never know whether one day someone will want to transmit your program. Remember, Broadcast Quality is not an optional extra. It is simply the minimum quality you should accept.
"We put stuff out like this all the time and no-one complains"
Read that line again and consider whether you really need that attitude?
"Soon, TV stations will all be transmitting D1 anyway, so ... etc,"
My Giddy Aunt! I don't believe I heard that! D1 is around 270MBits/sec. Cable maybe, but not television, not soon!
It could be argued that when you hook up to Foxtus and get your 3D-interactive-virtual- reality-television-on-demand piped down an optical fibre into your toaster then that will be true digital transmission and hence independent of those demon "specs" - but that would only really be true if you junked your old telly (and toaster) and hooked up a new digital set. And then, in order that you can download your Barry Manilow CDs from the internet, whilst watching Terminator and The Piano simultaneously, those images would have to be heavily compressed anyway. And compression relies on knowing what is black and what is white and what can be expected in between. And thats what the specs are for.
Read the Followup!
- Matthew Tucker