[FFmpeg-devel] Atempo limits

[Ronak Patel]

Thanks. Is it okay if I push a patch for this? How high of a limit does the algorithm support today?

Sent from my iPhone

> On Jun 4, 2018, at 8:00 PM, Pavel Koshevoy <pkoshevoy at gmail.com> wrote:
> 
>> On 06/04/2018 12:09 PM, Ronak wrote:
>> Hello,
>> 
>> How are you all?
>> 
>> We are looking to use the atempo filter for our audio files. However, the limit between 0.5 - 2x is too restrictive for us. We would like to expand the limit to 0.5x - 3x.
>> 
>> I tried changing the range in atempo.c and the rest of the tempo filter just worked.
>> 
> 
> Going below 0.5 is likely not going to sound good. Going above 2.0 should be fine.  The reason for current [0.5, 2.0] range is mostly for symmetry. atempo=0.5 followed by atempo=2.0 should sound like original audio.  This should also point you to an alternative solution -- put 2 atempo filters one after another to achieve tempo greater than 2  (atempo=2.0,atempo=1.5), or like this:
> 
> ffmpeg -i /scratch/Music/02\ Feeling\ Good.mp3 -af 'atempo=sqrt(3.0),atempo=sqrt(3.0)' -y /tmp/tempo-3x.wav
> 
>   Pavel.
> 
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