Using FFMPEG to extract video loses sync between sound and vision

[Tony Scholl]

On 9 February 2016 at 18:37, C E Macfarlane <c.e.macfarlane at macfh.co.uk> wrote:
> As per subject line, using this version of ffmpeg under Windows XP ...
>
> ffmpeg version 2.2.3 Copyright (c) 2000-2014 the FFmpeg developers
>   built on Jun 19 2014 20:24:25 with gcc 4.8.3 (GCC)
>   configuration: --enable-gpl --enable-version3 --disable-w32threads --enabl
> e-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutl
> s --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enabl
> e-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libm
> odplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-a
> mrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschr
> oedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libt
> wolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --e
> nable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enabl
> e-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-deckli
> nk --enable-zlib
>
> ... and trying to extract a section of this ...
>
> http://www.bbc.co.uk/programmes/b06z8cxd
>
> ... with the following command ...
>
> FFMPEG -i CuirmCeltic-2016-1.mp4 -acodec copy -vcodec copy -ss 1211.5 -to
> 1465 Chieftains.mp4

You could try putting the -ss option before -i. The seeking is done in
a different way -
see http://trac.ffmpeg.org/wiki/Seeking - which might give better
results (or maybe worse).

In any case, placing -ss before the input file should be much faster.

Tony

> ... leads to a result where the sound is out of sync with the vision.  Can
> anyone suggest a fix?
>
> C E Macfarlane
> www.macfh.co.uk/CEMH.html
>
>
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