[MPlayer-users] DVD Playback: ~200 ms A/V desync rehashed

[Michael Lampe]

Hi,

[I am one of those gawks that always need '-delay -0.2' for proper DVD 
playback.]

Here are some random things I can offer:

1) I have tried xine 0.9.13 + d4d plugin. It plays all my DVDs -- ok, I 
only have nine -- with very good A/V sync. Standard install, only vidix 
selected manually.

2) '-mc 0': Tried that. It changes A-V in the info line from [+-]0.0xx 
to -0.[123]xx depending on the DVD or chapter played. I'm not really 
satisfied with the result.

3) From http://arbor.ee.ntu.edu.tw/~jackei/dvd2avi/doc/issue.html:

The AC3/MPA/DTS Stream DELAY Computed by DVD2AVI
------------------------------------------------

This value is derived from the difference between audio and video PTS 
(Presentation Time Stamp), the real playback time of each audio and 
video packet. Please look at the real log ripped from CardCaptor Sakura OP1:

        Video Packets    [PTS: 0.223 sec]    I P B P B B
        Audio Packets    [PTS: 0.223 sec]
        Video Packets                        P
        Audio Packets    [PTS: 0.287 sec]
        Video Packets                        B B P
        Audio Packets    [PTS: 0.319 sec]
        Video Packets                        B
        Audio Packets    [PTS: 0.351 sec]
        Audio Packets    [PTS: 0.383 sec]
        Video Packets                        B
        Audio Packets    [PTS: 0.415 sec]
        Video Packets                        P
        Audio Packets    [PTS: 0.447 sec]
        Video Packets                        B
        Audio Packets    [PTS: 0.479 sec]
        Video Packets                        B
        Audio Packets    [PTS: 0.511 sec]
        Audio Packets    [PTS: 0.575 sec]
        Video Packets    [PTS: 0.790 sec]    I
        Audio Packets    [PTS: 0.607 sec]

The beginning of selected region is aligned to I-frame by DVD2AVI and 
only I-frame owns a PTS. DVD2AVI will start to rip audio packet from the 
decided I-frame. Assuming that we decide to rip from the second 
I-frame... The audio delay of second I-frame is computed as PTS(A) 0.607 
- PTS(V) 0.790 sec = -183 ms (audio is ahead) The playback time of 
audio/video packet is different, so we should cut out 183 ms of audio in 
order to synchronize.

...

According to statistics, the perceptual tolerance of audio/video skew is 
about 80 ms (2~3 frames).

4) I can offer a VOB (~250M) that clearly demonstrates the A/V desync in 
mplayer.


-Michael