[Ffmpeg-cvslog] r6772 - in trunk: libavcodec/vp6.c libavformat/flvdec.c

[Aurelien Jacobs]

On Mon, 23 Oct 2006 02:14:55 +0200
Baptiste Coudurier <baptiste.coudurier at smartjog.com> wrote:

> Hi
> 
> aurel wrote:
> > Author: aurel
> > Date: Mon Oct 23 02:10:18 2006
> > New Revision: 6772
> > 
> > Modified:
> >    trunk/libavcodec/vp6.c
> >    trunk/libavformat/flvdec.c
> > 
> > Log:
> > document the extradata protocol for VP6F
> > 
> > Modified: trunk/libavcodec/vp6.c
> > ==============================================================================
> > --- trunk/libavcodec/vp6.c	(original)
> > +++ trunk/libavcodec/vp6.c	Mon Oct 23 02:10:18 2006
> > @@ -19,6 +19,11 @@
> >   * You should have received a copy of the GNU Lesser General Public
> >   * License along with FFmpeg; if not, write to the Free Software
> >   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> > + *
> > + *
> > + * The VP6F decoder accept an optional 1 byte extradata. It is composed of:
> > + *  - upper 4bits: difference between encoded width and visible width
> > + *  - lower 4bits: difference between encoded height and visible height
> >   */
> >  
> 
> That could be a way to stricly indentify VP6F and remove CODEC_ID_VP6F.

That could be. But currently, the swf demuxer don't pass extradata to
the VP6F codec, so we would need to add a fake extradata byte in the
swf demuxer. This is a bit hackish too.

> Michael said that will break stream copy, but we still do that way for
> H264 (mov vs others), though mov muxer, correct bitstream before muxing.
> That's IMHO how things should be done, not using a different codec id.

If others agree I will implement this, but I'm still not sure this is the
right thing to do.
If you stream copy FLV VP6 into AVI and store it with the VP62 fourcc, it
will then be displayed upside-down. So IMO having a different fourcc for
upside-down flipped VP6 is the only proper solution for stream copy.

Aurel