[XviD-users] problem with simple profile mp4 in quicktime

[Jared Roberts]

[[ I sent this yesterday, without subscribing to the list.  I see
today that it still hasn't shown up in the archives, so I'm
subscribing to the list and re-sending.  Sorry if it shows up twice.
]]

Hello xvidians, I hope this list isn't as dead as it appears.  Sorry
if something like this has come up before, I googled around a little
and couldn't find anything.

I'm trying to create video files for playback in windows (encoding in
linux).  The main constraint is that it must be possible to easily
single-step frame-by-frame both forwards and backwards.  This pretty
much limits me to quicktime player as no other player I've found has
this capability.  So I've decided to try and create Simple Profile
MP4s so things work well out-of-the-box.  The video plays OK, but when
trying to single-step backwards, the video occasionally jumps forward
instead of moving back, but only for one frame.  So if I hit backward
continuously, the resultant frames are something like:

...
back 1 frame
back 1 frame
forward 3 frames
back 4 frames
back 1 frame
back 1 frame
forward 3 frames
back 4 frames
...

Here's what I'm doing:

XVIDENCOPTS=max_key_interval=4:hq_ac:vhq=4:quant_type=h263:me_quality=6
BITRATE=14000

mencoder input.avi -o /dev/null -of rawvideo -ovc xvid \
    -xvidencopts pass=1:$XVIDENCOPTS

mencoder input.avi -o output.m4v -of rawvideo -ovc xvid \
   -xvidencopts pass=2:bitrate=$BITRATE:$XVIDENCOPTS

tcextract -x pcm -i input.avi |  faac -o output.aac --mpeg-vers 4 \
    -P -X -R $SAMPLERATE -

mp4creator -c output.aac output.mp4
mp4creator -c output.m4v -interleave output.mp4
mp4creator -optimize output.mp4

The GOP is really small so that stepping backwards is fast.  The
bitrate is high, so the quality isn't too bad.  The resolution of the
input is 1440x480.  Don't worry about the sound unless I'm doing
something really catastrophic since it probably doesn't apply.  The
above is a simplification, and there's a good-ish reason why I'm using
raw pcm instead of wave :).

I presume the problem is with QT rather than xvid, but that's little
consolation, I'm afraid.  Interestingly, videos created last year with
xvid do not exhibit this problem, nor do videos created with divx.
I'm currently using xvid 1.1b2, I don't remember which version of xvid
was working for me last year, but the video then was 720x480, and
encoded thusly:

transcode -i "$input" -y xvid4,null -R 1,"$log" -w 14000,3 -V -o /dev/null
transcode -i "$input" -y xvid4  -R 2,"$log" -w 14000,3 -N 0x55 -V -o "$mpeg4"

If I'm doing something that's confusing quicktime, please let me know
how to fix it.  If Xvid is doing something incorrectly, please
consider this a friendly bug report.  If quicktime has a bug that's
being triggered by correct-but-different behavior in xvid, please
point me to a switch to turn off the new behavior if it exists (and if
it doesn't, please consider adding such a switch!)

Happy to provide any extra info I can.