[MPlayer-dev-eng] syncing issues (frame_time undefined)

[Dean Pierce]

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MPlayer 1.0pre8-3.4.6 (C) 2000-2006 MPlayer Team
CPU: AMD Athlon(TM) XP 2200+ (Family: 6, Model: 8, Stepping: 0)
CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 0
Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowEx SSE


Some of my videos would lose sync, and whenever that would happen, there
was an error message that looked something like this:

Invalid frame duration value (1302.634/1302.634 => -0.000). Defaulting
to 0.025 sec.

I grepped for the error message, and found it somewhere around line 597
in /MPlayer-1.0pre8/libmpdemux/video.c

Looking in that area I noticed that it seemed to be handling what
happens when frame times have negative values in certain types of video
streams.  It seems that the point of that code is to define what
frame_time should be based on the value of d, but when d is negative,
the value of frame_time remains untouched.  The value that ends up
getting used as the frame_time seems to be the frame_time of the
previous frame.

It seems to be that if the frame_time is invalid, the frame_time should
be set to zero.  On the line before the error message, I just put
frame_time=0; , recompiled, installed, and all my previously broken
videos played perfectly.

I did some basic testing, and it seems to work fine with the
modification, and even managed to resync properly when I forced a desync
with high cpu load etc.


This is really the first time I have looked into mplayer code, so I have
no idea if this modification is acceptable, as I have zero understanding
of the overall architecture.  I just wanted to watch those videos, and
had some spare time.  I thought I should inform the list, and I hope
that someone will find this tidbit of information useful :-)

   - DEAN
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