[FFmpeg-user] AVC / AAC 2 passes , Incomplete MB-tree stats file. message

jacky renaux.jacky at orange.fr
Tue Jan 22 10:48:19 CET 2013

Le 21/01/2013 23:57, Carl Eugen Hoyos a écrit :
> jacky <renaux.jacky <at> orange.fr> writes:
>> Le 21/01/2013 16:35, Carl Eugen Hoyos a écrit :
>>> jacky <renaux.jacky <at> orange.fr> writes:
>>>> set lcmda1=    -an
>>>> set lcmda2=    -acodec libvo_aacenc -ab 48k -ar 22050 -ac 1
>>> Does it also fail if you use the same options for lcmda1 as
>>> for lcmda2 ?
>> it does not fail if I use lcmda2 for pass 1 and pass 2
> I absolutely may miss something, but to keep A/V-sync, it is not
> unusual to drop or duplicate frames (it is actually the default
> behaviour). This of course never happens with -an (no audio, no
> A/V sync to take care of). So depending on your input sample
> (and the chosen output container), -pass 1 -an vs -pass 2
> -acodec ... may lead to a different number of frames and that
> definitely hurts the rate-control badly.
> Carl Eugen
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Hi Carl
I am getting confused , the doc says

‘-pass n’

    Select the pass number (1 or 2). It is used to do two-pass video
    encoding. The statistics of the video are recorded in the first pass
    into a log file (see also the option -passlogfile), and in the
    second pass that log file is used to generate the video at the exact
    requested bitrate. On pass 1, you may just deactivate audio and set
    output to null, examples for Windows and Unix:


    ffmpeg -i foo.mov -vcodec libxvid -pass 1 -an -f rawvideo -y NUL
    ffmpeg -i foo.mov -vcodec libxvid -pass 1 -an -f rawvideo -y /dev/null

then is this deactivate audio not any more valid ?
I did it since 3 years (h263) with succes


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