[FFmpeg-user] How to slow down a video

Michael Koch astroelectronic at t-online.de
Tue May 5 14:25:39 EEST 2020

Am 05.05.2020 um 13:21 schrieb Ulf Zibis:
> Am 04.05.2020 um 12:56 schrieb Michael Koch:
>> Am 04.05.2020 um 11:00 schrieb Ulf Zibis:
>> >//>/Am 27.03.20 um 04:06 schrieb Ted Park: />>/Hi, />>//>>>/for 
>> video: -vf setpts=0.5*PTS />>>/for audio: -af atempo=2 
>> />>//>>/Actually, he wanted to slow down the video so you probably 
>> meant the />>/reciprocal of this, 2*PTS and atempo 1/2 />//>/Thanks 
>> alot, this works fine. />//>/Now I want to tweak a little bit more. I 
>> want to slow down the video />/by 1.4 and then increase the audio 
>> frequency by 1.25. So I did: />/ffmpeg -i in.mp4 -vf setpts=PTS*1.4 
>> -af />/asetrate=48000*1.25,atempo=1/1.25/1.4 out.mp4 />//>/This 
>> resulted in really bad audio quality. The reason is maybe, that 
>> />/the sampling rate of the output was transformed to 64.000, but I 
>> want />/48.000. I guess there is a possibility to get a better result 
>> by using />/-af aresample, but I have problems to understand it's 
>> syntax. /
>> try  -af aresample=48000
> Do you mean, I should add this at the end of my filter chain? I can't 
> imagine, that using it singular instead would do what I want.

yes, add it at the end of the filter chain.


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