Michael Niedermayer wrote: [avi way or highway] Not sure, I'd rather have a bitfield as hint in the info packet and just let advanced player and decoders know about it. I won't use avi just because the twocc for audio. Proponents of alternative systems consider them because they don't like the idea of cluttering the tag list with producer specific and nonstandard tags while you may archive the same result adding an optional field to explain what you should do. if $specific_encoder got to the point of being standard but retains the tag it used when wasn't standard at all what would happen to the decoder if you just store the information "format mp4v, encoded by xvid, workarounds A,B,C" as XVID? if you store it as tag = mp4v X-encoder= "xvid-$ver_pretty_sane" - players not caring could try to play it at their best and in this case have no problems. - players with a complete decoder will see the lack of hints and decode it properly - players particularly smart could also use the encoder string and pick the matching decoder if present. if you just store the tag as XVID - players will still try to play it as if the workarounds are necessary and maybe trigger workarounds that aren't meant to be used. - players not knowing about XVID will still either play the guess game or give up. On the other hand: - using different tags you deliver the information in a more compact (but more ambiguous) form - having hints and other metadata as described looks overengineering quite a bit and will require some work to support it properly (if we care just about lavc it isn't that hard, but...). Did I sum up Michael position and the previous ones correctly? lu - yes, I don't have strong opinions about it, I just want to have NUT out as soon as possible. lu -- Luca Barbato Gentoo/linux Gentoo/PPC http://dev.gentoo.org/~lu_zero