Using FFMPEG to extract video loses sync between sound and vision

[Christopher Woods]

Not tried on iPlayer stuff, but with FLVs I now always try the -copyts 
flag, this gave me success remuxing an FLV to MP4 (non-iPlayer) with a 
variable video frame rate.

Also a single "-codec copy" will save you some keypresses.

Chris


On 10 February 2016 14:13:27 Tony Scholl <ajscholl at gmail.com> wrote:

> 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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>
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