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I'm curious, is it possible to do frame-perfect audio cutting using ffmpeg's complex filter graphs + frame filtering aselect functionality?

I've tried a bunch of other approaches (using -segment_times and -ss/-t) - they worked but were only ~0.02sec accurate, just for reference:

  • ffmpeg -f lavfi -i "sine=frequency=1000:duration=5" -ar 48000 test.wav
  • ffmpeg -y -i test.wav -f segment -segment_times "1.55,2.00" -segment_list_type csv -segment_list output.csv test%04d.opus
  • ffmpeg -y -i test.wav -ss 0.00 -t 1.55 test0000.opus -ss 2.00 -t 1.00 test0001.opus

My filter-based attempts:

  • ffmpeg -y -i test.wav -ar 48000 -af "aselect=between(samples_n\,100\,16100)" test0000.opus as an example but this produces a 5-second long test0000.opus instead of a 0.25-second one
  • ffmpeg -y -i test.wav -ar 48000 -af "aselect=between(t\,0.0\,1.55)" test0000.opus kind of works, but still gives a 1.57-second audio instead of 1.55-second one.

Can this be done in principle using frame filtering? Am I missing something in these commands above? If the filter-based approach is not more accurate, I will fall back to my initial attempts.

Thanks!

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  • Same issue as video.stackexchange.com/q/26451
    – Gyan
    Sep 27, 2023 at 18:40
  • I think the linked issue is about generation of files of specific duration while here I'm inquiring about cutting from an input PCM with sample-perfect provided boundaries (I realize that some padding may appear during encoding to opus, but I care that input cutpoints are as sample-precise as possible) Sep 28, 2023 at 15:13

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