FFMPEG change Tone Frequency, keep length (Pitch Audio)

Question

How can I change the Tone frequency. This Example only pitches it by keeping the old tone frequency and only decrease the length of File.

For Example, I have a constant 100 Herz tone (as mp3) and I want it to change 90 Herz

 ffmpeg -i 100h.mp3 -af atempo=100/90 90h.mp3

This Example doesn't work for me, it sounds the same

score 20 · Accepted Answer · edited Sep 26 '22 at 12:04

20

finally, by combining the asetrate and resample from Gyan, with atempo, the following works and preserves also the audio length

for example: use 0.9 for 90% of the frequenz

 ffmpeg -i test.mp3 -af asetrate=44100*0.9,aresample=44100,atempo=1/0.9 output.mp3

edited Sep 26 '22 at 12:04

Hugh Perkins

answered Nov 19 '18 at 14:41

dazzafact

how? where does the 1.1 come from? is it meant to be 1/0.9 ? – theonlygusti Nov 28 '20 at 00:16
yes, you can also use 1/2(0.5) for the half of it, or 2/1(2) for double it – dazzafact Nov 29 '20 at 09:00
why didn't you use more decimal points? 1.1 is quite a poor approximation of 1/0.9 – theonlygusti Nov 29 '20 at 11:01

score 9 · Answer 2 · answered Nov 19 '18 at 13:49

9

Basic method is

ffmpeg -i 100h.mp3 -af asetrate=44100*0.9,aresample=44100 90h.mp3

where 44100 should be replaced with the input sample rate.

answered Nov 19 '18 at 13:49

Gyan

2 Answers2