> Thanks for the explanation > > One thing puzzles me though, if it is true that there are only a > finite number of PARs, why isn't this value stored in an enum or > something?
I would agree that adding these commonly used ratios to the library would be useful. > > > It would seem to me that adding the possibility to create custom PARs, > while the standards do not support this, is a sure way to get a lot of > non-standard formats out there.. This would be true if we were only using Rec.601 formats (standard def mpeg1, mpeg2) which were captured from analogue sources. However files can come from any source. So may not be limited to the ratios specified. > Not that I'm suggesting that libav* should have less flexible options, > but it seems unnecessary to add functionality which the standards do > not support. I know that the majority of files I've encountered are square pixels or Rec.601 There may be the odd analogue file that uses a different ratio. Plus it's easier to code for an arbitrary x:y pixel aspect ratio than it is to have a case for the 10 (or so) most commonly used ratios. It's really up to the software authors to get it right, however many of them aren't video engineers and make the same 720x576 = 16:9 assumption. The results are close enough that it is difficult to see that the scaling isn't exact. Mark _______________________________________________ libav-user mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/libav-user
