television traffic

[aerowolf]

'traffic'. When we hear this word, we tend to think of "that stuff that we drive through", aka "that stuff that makes us late and irritable and and miserable". However, when it comes to television (and radio, I would presume, but I don't know for certain on this score) it's a word that means "keeping the signal from being black

Comments

[techkitsune]

Good luck getting it done, even Clear Channel stations can't synchronize this stuff reliably.

[aerowolf]

I know. (And if Clear Channel can't do it, how can anyone else?)

Basically, I'm writing down what I learn at the station, and as I write it I think about other parts of the problem, which usually leads me to understand the larger issues that have led to the current situation. Once I understand those, then I can work with them reliably.

This isn't to say that I won't screw up during it. It just means that I won't try to do something based on an incorrect assumption.

[aerowolf]

The 29.97 thing (technically 1000 frames over the time that 1001 frames would normally play) is specifically related to getting stationary dot patterns off the screen as quickly as possible.

From http://en.wikipedia.org/wiki/NTSC#Color%20encodingWhen a transmitter broadcasts an NTSC signal, it amplitude-modulates a radio-frequency carrier with the NTSC signal just described, while it frequency-modulates a carrier 4.5 MHz higher with the audio signal. If non-linear distortion happens to the broadcast signal, the 3.58 MHz color carrier may beat with the sound carrier to produce a dot pattern on the screen. To make the resulting pattern less noticeable, designers adjusted the original 60 Hz field rate down by a factor of 1000/1001, to approximately 59.94 fields per second

[alinsa]

I'd be surprised if all this goes away in 2009. The deadline is only for stopping *broadcast* of NTSC. Yet, 90% of the US gets their NTSC via satelite or cable, which I suspect will hapilly keep not upgrading their equipment. ;)

Okay, well, satelite is digital, but given that the non-HD channels are meant to end up as an NTSC signal, I wouldn't be surprised if there was a 1:1 correspondance between frames in the datastream and frames/fields on the TV. But I don't know if that's actually the case. Feel free to clue me in on that one...

*snuggles*

[aerowolf]

As neillparatzo mentions, TVs will happily sync to something that's even approximately 60 fields per second. The digital streams from satellite generally work out to a true 30fps. (yay MPEG-2.)

...which is something I forgot to mention, some of our broadcasts are rebroadcast directly from the satellite. Which throws the timing off even more. (This might be a technical reason for having intermission/commercial time.)

There should be a 1:1 correspondence between frames in the datastream and frames in the TV; same with fields.

*snugs*

[foomf]

Don't forget the ever-exciting fact of VHS VCRS and DVD players that will continue to exist, providing Never Twice Same Color signals for another decade.