Television, and the things that suck...
So I'm working (very part-time) at a television station, KHMP-LP/KPVT-LP in Pahrump, Nevada. I'm nominally in accounting/bookkeeping, but you can't be around there without picking up at least some operations knowledge... and that operations knowledge is what I'm writing about today.
A television station (specifically, the generation of the A/V content signal) is made up of a lot of complex, complicated workflow that needs some fairly careful synchronization and cooperation between the various equipment that does it all. Each piece does a very useful thing... but there are so many pieces that it's almost impossible to synchronize them.
In the simplest case, you have the A/V source, hooked directly to the transmitter. This can be as simple as a DVD player -- drop in a DVD, hit play, and suddenly you have video. There's a lot of black time in there, though, while you get it set up. And if you want to play something like a commercial, you're kinda screwed unless you eject the DVD, drop in another DVD that has the commercial, play the commercial (oh, right, you need to select it via the menus), eject it, drop the original DVD back in there, seek to the right time in the thing, hit play, and repeat as often as you want to have commercials.
Needless to say, bad thing to try to deal with. And this doesn't even mention the concept of different audio levels between the content and the commercial.
So, you bring in two separate DVD players, one for the content, and one for the commercials, and you put a mechanical switchbox in between the two. You can pause the content and run the commercial, switching between them. Except... well, they don't generate sync at the same rate or the same time. This causes the recipients of the signal to have to watch as their receivers re-synchronize themselves with the different sync signals.
Okay, not a problem. We'll put something in the way called a "frame sync" -- that is, framing information is generated by that, and that framing information is used as the master sync source. Every other source's sync signal is dropped.
So, you have two DVD players. This requires that you be there, 24 hours a day, 7 days a week, to move the switchbox back and forth between them. You've gotta sleep sometime... so instead, you put a recorder/player on it (a VCR, or a digital recorder kind of like a TiVo).
But how do you keep track of the lengths of time involved? How do you keep track of the content, versus your commercials? Remember that TV is scheduled by the blocks of time (usually in increments of 30 minutes), and those divisions are absolute. You have 29.97 frames playing per second (that's 2997 frames in 100 seconds, 29970 in 1000 seconds, and so on). You have to make sure that your audio processing stays synchronized (remember the "audio levels between the different DVDs" problem?).
Nowadays, there are computers which can do video, and computers are nothing if not good at maintaining and using structured information. (You know, like "play this clip, X amount of time/frames into it, for Y length; after that, play this clip, X amount of time into it, for Y length", ad nauseum.) But, would you believe, there's no free software to do that? Would you believe that the cheapest broadcast box costs $200k?
A television station (specifically, the generation of the A/V content signal) is made up of a lot of complex, complicated workflow that needs some fairly careful synchronization and cooperation between the various equipment that does it all. Each piece does a very useful thing... but there are so many pieces that it's almost impossible to synchronize them.
In the simplest case, you have the A/V source, hooked directly to the transmitter. This can be as simple as a DVD player -- drop in a DVD, hit play, and suddenly you have video. There's a lot of black time in there, though, while you get it set up. And if you want to play something like a commercial, you're kinda screwed unless you eject the DVD, drop in another DVD that has the commercial, play the commercial (oh, right, you need to select it via the menus), eject it, drop the original DVD back in there, seek to the right time in the thing, hit play, and repeat as often as you want to have commercials.
Needless to say, bad thing to try to deal with. And this doesn't even mention the concept of different audio levels between the content and the commercial.
So, you bring in two separate DVD players, one for the content, and one for the commercials, and you put a mechanical switchbox in between the two. You can pause the content and run the commercial, switching between them. Except... well, they don't generate sync at the same rate or the same time. This causes the recipients of the signal to have to watch as their receivers re-synchronize themselves with the different sync signals.
Okay, not a problem. We'll put something in the way called a "frame sync" -- that is, framing information is generated by that, and that framing information is used as the master sync source. Every other source's sync signal is dropped.
So, you have two DVD players. This requires that you be there, 24 hours a day, 7 days a week, to move the switchbox back and forth between them. You've gotta sleep sometime... so instead, you put a recorder/player on it (a VCR, or a digital recorder kind of like a TiVo).
But how do you keep track of the lengths of time involved? How do you keep track of the content, versus your commercials? Remember that TV is scheduled by the blocks of time (usually in increments of 30 minutes), and those divisions are absolute. You have 29.97 frames playing per second (that's 2997 frames in 100 seconds, 29970 in 1000 seconds, and so on). You have to make sure that your audio processing stays synchronized (remember the "audio levels between the different DVDs" problem?).
Nowadays, there are computers which can do video, and computers are nothing if not good at maintaining and using structured information. (You know, like "play this clip, X amount of time/frames into it, for Y length; after that, play this clip, X amount of time into it, for Y length", ad nauseum.) But, would you believe, there's no free software to do that? Would you believe that the cheapest broadcast box costs $200k?