THINKING -- thinking -- PAL and NTSC are output formats, not transport systems, That sure stretches my memory. It matters in Video tapes - maybe in analog, but at least some DVD's will work on either machine and one machine I used at a convention, had both outputs available - along with S-video and component. Now you got me thinking -- could be dangerous
It's true that NTSC and PAL are output formats, but they are also source/input formats before the MPEG-2 is encoded and uplinked.
MPEG-2 takes individual video "frames" for input. The number of frames per second and the resolution of each frame is different between PAL and NTSC. The MPEG-2 encoder looks at multiple frames and does a bunch of clever mathematical operations like DCT, motion estimation, huffman encoding, run-length encoding, and other stuff to compress the source video. The compression part's the same regardless of input format. BUT, to oversimplify, both the number of pixels per frame and the number of frames per second going up to the satellite and out of your STB decoder are directly tied to whether the source material was PAL or NTSC.
If the uplinked signal carries PAL video, the output of your STB decoder will have the wrong frame rate and resolution. So somehow the STB has to resample and resize the decoded image before it can be output to your NTSC TV set, and I have no clue at all about how that's actually done.
But it must not be too easy, because I've noted that STBs are often rated on how well they do the PAL->NTSC conversion internally.
Turns out, most or perhaps all of the popular FTA boxes detect and convert the input format to the output format automagically.
At least, I think this is true to the best of my knowledge. I'm still working on understanding all this stuff, so corrections are welcome. I find this stuff really really interesting!
