[FFmpeg-user] Title slug stretched out, and audio/video are out of sync

[Dan Cavallaro]

Part of what I do at work involves taking DVDs of lectures that we get
from various universities, and then I import the DVD into Ulead
VideoStudio, trim the ends if necessary, and add a 10-second title
slug before the video starts, then export to MPEG-2, where we
transcode to various formats.

We've been using watch folders with a Procoder back-end for a while,
but it's been pretty finicky so we're looking into other methods. I've
been experimenting with ffmpeg, because it does all of the different
conversions that we need. As an experiment, I tried transcoding one of
our MPEG-2s to h.264 MP4. Something really strange happened though -
the audio and video were out of sync, but in a weird way. The title
slug at the beginning lasted for 18 seconds instead of 10, and then
the audio and video were consistently out of sync for 8 seconds for
the entire duration of the video.

I then added the "-async 2" option, and now the audio and video are
synced properly, but the title slug is still 18 seconds instead of 10
seconds. How could ffmpeg just stretch the title slug and nothing
else?

The command line options I'm using are:

ffmpeg -i input.mpg -vcodec libx264 -b 302k -acodec libfaac -ac 1 -ar
44100 -ab 48k -r 29.97 -s 320x240 -async 2 output.mp4

Thanks,
Dan