Opened 12 years ago

Last modified 8 years ago

#879 new defect

mplayer/mencoder a/v sync problem

Reported by: nopreceja@… Owned by: reimar
Priority: very important Component: core
Version: 1.0rc1 Severity: major
Keywords: Cc: nopreceja@…, shingen20092009@…, serho_gtmax@…
Blocked By: Blocking:
Reproduced by developer: Analyzed by developer:


I think that i have found an a/v sync bug in mplayer/mencoder.
If i play (or convert) this video in mplayer.exe ,then it is absolutely out of a/v sync (to play video in mplayer.exe just drop a video to mplayer.exe). It has 10 seconds sound gap on the begining and then the sound start to play (so it will start to play the late and then is whole video faster than should to be)
I tested it on official version rc1 and also on this newest unofficial developer build of mencoder

(made at May 29, 2007).

I have also tryied to play it with paremeters which are written "Bug report guide":
mplayer.exe Truth_about_islam_from_an_ex-muslim_lady.flv -framedrop -ni -nobps -mc 0
but it was the same as before.

Mencoder using Mplayer (respectively the same code) for decoding of video. I also tryed to convert/play the same video with ffmpeg and a/v sync was ok, and Mplayer/Mencoder? (i think, i`m not sure) is based on ffmpeg, so maybe it using an old version of ffpeg. I have also tried to play this video in FLV Player and Media Player Classic with ffdshow codec and in both cases was everything ok. So it must be bug of Mplayer/Mencoder?.

Im using Windows XP Home and platform x86 (Pentium M). Im not only who has this problem, many people told me that the have the same problems with .flv files.

Change History (5)

comment:1 Changed 12 years ago by reimar

I just added this to the FAQ:

Many FLV files will only play correctly with <option>-correct-pts</option>.
Unfortunately MEncoder does not have this option, but you can try setting
<option>-fps</option> to the correct value manually if you know it.

-fps 15 seems to be the right value for this file.

comment:2 Changed 12 years ago by nopreceja@…

  • Cc nopreceja@… added

It works with your attitude, but because i have Windows, so i usualy dont use Mplayer, i using only Mencoder, and as you said it dont have -correct-pts option, so it will be extremely masochistic for each video to find right fps. And in addition, the mencoder always say that inserted .flv video have 29.970 fps although one which i inserted have 15 and second have 25 fps. So it is definitely bug, at least the fps value what the mencoder print into stdout. For any other non-flv video which inserted (i converted about 1000 videos with fps value which mencoder sayied in stdout) is the a/v sync absolute ok, when i converted with value from stdout. And your attitude is impossibe to use if you using script or batch conversion.

I`m using this attitude (respectively my application which i have written):

1)first i run mencoder with -NUL output:
mencoder.exe Truth_about_islam_from_an_ex-muslim_lady.flv -o NUL -endpos 0:0:0:1 -oac pcm -ovc copy

(from this text output i parse the fps value and other additional information)

2) convert audio and video separately (it will make two files, for example .cmp for video and .mp3 for audio) and then i mux it together in ffmpeg (maybe you think now that i`m crazy, but this atttitude have the best A/V sync possible, thousand times better than direct conversion + mux in mencoder, only flv files have problems with this attitude due to nonsense fps mencoder text output)

comment:3 Changed 12 years ago by reimar

Please look up the word "attitude" in a dictionary, you use it in a very confusing way.

So it is definitely bug

No disagreement here, which is why I did not close it (though I think there is already at least one other bugreport about the same thing somewhere here, so it is a duplicate).
I only wanted to provide you with a workaround, I don't think it will be fixed any time soon, sorry.

comment:4 Changed 8 years ago by shingen20092009@…

  • Cc shingen20092009@… added
  • op_sys changed from Other to MinGW
  • rep_platform changed from PC (x86 with SSE) to PC (x86)

comment:5 Changed 8 years ago by serho_gtmax@…

  • Cc serho_gtmax@… added
  • op_sys changed from MinGW to Linux
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