[MPlayer-users] Audio Sync problem with Inv Telecined Video

[Jeff Schiller]

I've just noticed this very weird problem, I'm hoping someone can help me out:

1) the original source was 24fps film, it was telecined and was
interlaced at 30fps for NTSC video
2) I am capturing this NTSC video as a raw AVI
3) I'm using TMPGEnc to convert this AVI into MPEG-2 format, because
of #1, I'm using the Encode Mode of "Inverse 3:2 pulldown"
4) The resultant MPEG file plays fine in Windows Media Player, PowerDVD, etc

However, when I try to play it in mplayer (in either Windows or Linux):

- mplayer my.mpg :  (defaults to 30 fps) and this results in the audio
steadily falling behind the video, I mean within 5 minutes, the audio
is lagging by over 12 seconds from the video

- mplayer -fps 24 my.mpg : this results in the audio beginning AHEAD
of the video but then gradually getting in sync with the video (this
seems to happen very near the 90 second mark).  The funny part is that
after this 90-second mark, the audio and video stay completely in sync
for the duration of the video (in other words, the audio doesn't
continue to fall behind the video)

- mplayer -fps 25 my.mpg - same as fps=24 except by about the
60-second mark the audio is in sync with the video and stays that way
throughout

- mplayer -fps 26 my.mpg - stays in sync after the 30-second mark

- mplayer -fps 27 my.mpg - audio/video in sync for the duration of the video

- mplayer -fps 28 my.mpg - audio gradually falls behind the video at a
slower rate than the default (fps=30)

Anybody else experience this?  Why would this happen?

Obviously the solution for me currently is to always play the videos
at fps=27, but I have no idea where that number comes from other than
imperical testing and it doesn't explain why other video players can
play the video with no special options and have no sync issues.

mplayer bug?

Thanks,
Jeff