downsize interlaced

[Gavino]

An analogue SD broadcast (you still have those?) wouldn't be (anamorphic) widescreen.
http://en.wikipedia.org/wiki/Palplus

[pantau]

As far as I know, the squeezing is done at transmission time, not on the archival Beta, but I may be wrong...

[TheSkiller]

Yes, letterboxing, if needed, is done on the fly, IF the broadcaster supports digital anamorphic broadcast. If not it is letterboxed prior for all types of reception.

It doesn't actually really matter whether it's going to be broadcast analog or digital or in letterboxed or anamorphic because SD digital derives from analog and letterbox just means the scanlines get squashed to 0.75 times the original amount of scanlines. Horizontally everything stays the same. So it's quite simple.

And the reason an NTSC based broadcaster uses 486 scanlines is simply because you need 486 scanlines to represent a full NTSC image (and for compatibility of legacy material).
For digital broadcast six of those scanlines get chopped off before encoding to MPEG2 SD.
The same happens with DVD. It's just that these days, of course, lots of stuff is produced with 480 scanlines only as this is more commonly used in digital film making. But still, it doesn't matter, it just means that six scanlines in an analog NTSC signal stay black which nobody ever sees.



So what is then the real NTSC PAR? 40/33 or 5760/4739?Well, 5760/4739 is (probably) the most accurate one if we're taking the analog timings as strict as can be, while 40/33 is the one suggested by the MPEG4 and it is generally very common in the digital domain. Both are so close to each other that for all practical applications, I'd say, it doesn't matter which one you use.

[2Bdecided]

Thanks all - I've learned something!

Though Brazil isn't NTSC ;) (though it is 525i60).

Cheers,
David.

[pantau]

before the transmission stage, it is ntsc ;)

[TheSkiller]

Do they send out analog NTSC for transporting the broadcast from the broadcaster to the satellite/cable/terrestrial transmitter?

What 2Bdecided actually meant was that the analog color modulation used in Brazil is not NTSC but PAL which means an analog broadcast in Brazil is PAL-M. That's 525 (486) lines at 60 Hz but with PAL color so it's called PAL-M as "NTSC" and "PAL" mainly describe the (analog) color coding, not necessarily the amount of lines and the frequency.

[pantau]

no... i only meant to say that all production is done with ntsc equipment. once in transmission stage, it becomes "PAL-M" (TV sets for instance are already PAL-M)

[smok3]

you don't really mean the old analog betacam SP tape?