Re-encode flac files in order to preserve duration

[mifi]

When trimming flac files using copy the duration doesn't get updated and remains as the original. Only happens with flac audio files. This is a bug in ffmpeg that seems will not be fixed. So we could workaround it by re-encoding flac (because it is lossless even when encoding, even though slower)

Originally posted by @hazerflac7 in #1320

[sahiljr-111]

This can be done by converting them to a different format and then back to FLAC.

1. convert the FLAC file to a .wav -> ffmpeg -i original.flac -c:a pcm_s24le intermediate.wav
2. trim the file -> ffmpeg -ss start_time -i intermediate.wav -to end_time -c:a pcm_s24le trimmed_intermediate.wav
3. convert trimmed file to FLAC -> ffmpeg -i trimmed_intermediate.wav -c:a flac final_trimmed.flac

[Freso]

Those specific commands would drop any metadata from the FLAC though, though I guess there are ways to add that back.

Is there an upstream (ffmpeg) issue/ticket for this?

[mifi]

I've found these:

• https://trac.ffmpeg.org/ticket/10287
• https://trac.ffmpeg.org/ticket/4905

[sahiljr-111]

@Freso you can use additional options to copy the metadata from the original FLAC file to the final trimmed FLAC file

[Gevaarlijk]

I've found an app called Audacity that cuts flacs the way it should without messing up the times.

[mifi]

losslesscut can also do it now, if you want you can test it in the latest nightly build: https://github.com/mifi/lossless-cut/actions/runs/10585664608