[Ffmpeg-devel] About converting individual WAV file

Michel Bardiaux mbardiaux
Mon Jan 16 10:42:46 CET 2006

M?ns Rullg?rd wrote:
> "Takeshi.Tanaka" <ztanaka at esbd.ndss.jp> writes:
>>Hi this is Japanese developer team.
>>Could you give me a good idea after reading this mail?
>>Converting a MPG file to individual WAV file by command-line,
>>test1.wav and test2.wav overlap each other for 0.5sec.
>>So that we cannot listen test1.wav and test2.wav correctly.
>>This overlapping problem is only between test1.wav and test2.wav.
>>Command Line coding
>>~ffmpeg -i input.mpg -ss 0 -t 30 test1.wav
>>~ffmpeg -i input.mpg -ss 30 -t 30 test2.wav
>>~ffmpeg -i input.mpg -ss 60 -t 30 test3.wav
>>Am I mistaking anything here?
> Seeking in MPEG files can never be very accurate.  

I dont agree. Seeking *can* be perfectly accurate *if* the file has been 
properly muxed, using correctly spaced timestamps. Extra precautions 
like constant closed GOPs should help too. Its just that ffmpeg does not 
try very hard to seek accurately, on the grounds that many files do not 
follow these rules!

> You could instead
> decode the audio stream from the entire MPEG file (or however much of
> it you need) to a single WAV file, and then cut out pieces from that.

Or cut the file with mpgtx.

Michel Bardiaux
R&D Director
T +32 [0] 2 790 29 41
F +32 [0] 2 790 29 02
E mailto:mbardiaux at mediaxim.be

Mediaxim NV/SA
Vorstlaan 191 Boulevard du Souverain
Brussel 1160 Bruxelles

More information about the ffmpeg-devel mailing list