aspect ratio vs pixel count

[DrP]

Over here in Australia, digital TV is (supposed to be) all transmitted as 16:9. The ABC, 7, 9 and SBS all transmit as 720 x 576, but 10 (don't you just love those channel names?) transmits as 704 x 576.

I believe that DVD playback of 704 x 576 is a trick mode where the DVD player decodes the video as 704 x 576 on a 720 x 576 plane which effectively pads the line with 8 black pixels a side, but how would the mpeg decoder in a STB handle 704 x 720? Would it also pad like that? I know that other dot counts such as 480 x 576 are decoded into the output buffer as 720 x 576.

I am trying to determine what AR I should flag the file for PC playback after encoding to XVID in a Matroska container. Should it be set to 1.778 or 1.738?

Is anyone able to authoratively answer as to how a STB handles 704?

[Kika]

Hehe, you'r wrong. ;) 704x576 is the "true" PAL-Resolution, not a Trick.
720x576 contains 16 Pixels of not defined Overscan. This Overscan Area may contain black borders, or Picture data but will not displayd on a correct working output device.
And there are two "families" of Resolutions: The Overscan-familiy and the "true" family:

Overscan:
720x576
544x576
480x576

True:
704x576
528x576
352x576

Do a research here at the board, you will find lot's of explanations about this.

[DrP]

Yes, I know about the 702 samples per line etc, but the question was how does the mpeg decoder in a STB handle the 704. If it takes as it handles 480 x 576 it would be painted into the output buffer as 720 x 576 (yes, I know there is front and back porch in there), however it seems that the 704 trick is also handled by STBs. I searched for some 4:3 video in the recording and found it is 528 x 576.

So it seems 704 x 576 is painted into the output buffer as 704 on 720 not expanded to 720 on 720 (in otherwords it behaves as does a DVD player).

[Kika]

So it seems 704 x 576 is painted into the output buffer as 704 on 720 not expanded to 720 on 720 (in otherwords it behaves as does a DVD player).

Different Players may handle this different. But the correct way is to fill the 52us of a line with the 704 Pixels, no matter if the Video is encoded in 704 with or without letterboxing to 720.
My Denon-Player is acting this way. You will see absolutly no difference between a Video encoded to 704x576 and the same Video encoded to 704x576 and letterboxed to 720x576.
My Afreey is an other story. This Player shifts the Video a bit to the upper left corner. So the letterboxed Version is more centered.