Start them on keyframes when reasonable, and delay writing audio packets
to help ensure that there's audio samples available for the first frame in
clusters.
Patch by James Zern <jzern at google>
Originally committed as revision 23473 to svn://svn.ffmpeg.org/ffmpeg/trunk
This isn't exactly semantically equivalent, but the field has already been
long abused to mean this, and writing it helps in determining a decent cfr
time base when transcoding from a mkv where the video codec stores none (VP8).
Originally committed as revision 23284 to svn://svn.ffmpeg.org/ffmpeg/trunk
This takes into account whether the granule defines the start or end times
of packets, and sets the correct file offset of the associated page.
Originally committed as revision 22462 to svn://svn.ffmpeg.org/ffmpeg/trunk
Otherwise it gets set automatically to a page midstream and prevents seeking
to the first page.
Originally committed as revision 22454 to svn://svn.ffmpeg.org/ffmpeg/trunk
Seeking on image sequences doesn't actually work, so this
test isn't very useful until that capability is added.
Originally committed as revision 22286 to svn://svn.ffmpeg.org/ffmpeg/trunk
