[Ffmpeg-devel] [PATCH] dv pixel format encoding fix

[Roman Shaposhnick]

On Fri, Mar 10, 2006 at 01:44:12PM +0100, Michael Niedermayer wrote:
> Hi
> 
> On Thu, Mar 09, 2006 at 11:00:07PM -0800, Roman Shaposhnick wrote:
> [...]
> > > what dv in mov is, is a sick double layer format, its the output of the
> > > dv muxer put into mov, the only sane way to generate this if we really have
> > > to support it and IMHO it would be better if we simply say "NO" to this mess
> > > is to feed the seperate audio and video dv streams into the dv muxer and then
> > > the combined muxed dv stream into the mov muxer, how to implement this
> > > cleanly is not exactly obvious, one way would be to call the dv muxer from
> > > the mov muxer to combine the streams
> > 
> >   That's pretty much what's going on in avi*.c on the decoding side when
> >   DV-in-AVI type 1 is given to the ffmpeg. I also think this is the only
> >   way to go, however, what's not clear to me is how widespread this double
> >   layering could be. Is DV really special in that regard or do things like
> >   AVI-in-MOV or some such happen in real life ?  
> 
> MPEG-PS in MOV 
> 
> vorbis in ogg in avi, the most braindead thing imaginable, vorbis due to
> its variable number of samples _and_ bytes per packet is problematic in
> avi, its possible to store but hackish, storing vorbis in ogg in avi has
> no effect on the problem (obviously) as either you can or cannot correctly
> store X in Y, a middle layer wont really help

  Wow! I have never suspected the world is *so* weird ;-)

  But anyway, the problem at hand (at least for DV) is not actually a decoding
  one (although it will be a problem if I get around to implementing metadata
  streams). The problem is with encoding. Or better yet -- with tools like 
  FCP expecting to find audio in VIDEO only DV streams embeded in MOV and/or
  AVI.

  IOW, we've got an application (ffmpeg in this case) happily doing:
     
     avcodec_encode_video(dv_encoder, buffer, buffer_size, &picture);
     ...
     pkt.data = buffer;
     ....
     av_interleaved_write_frame(mov_or_avi_output_format, &pkt);

  but in reality (in order to satisfy things like FCP) the last line should
  more like:

     av_interleaved_write_frame_doubly_wrapped(mov_or_avi_output_format,
                                               dv_output_format,
					       &pkt);

  Sooo, may be the right way would be to make applications deal with it by
  providing 'av_interleaved_write_frame_doubly_wrapped' ?

Thanks,
Roman.