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> if you're on macOS, use aac_at instead. Those are much better encoders and ffmpeg can use them as external libraries. Hey, do you happen to know if aac_at is
by Wowfunhappy 5y ago
> if you're on macOS, use aac_at instead. Those are much better encoders and ffmpeg can use them as external libraries.
Hey, do you happen to know if aac_at is encoding at the slowest speed? (Most compression efficiency but longest encoding time). I can't figure out for sure, so I keep bouncing audio through afconvert since it lets me set `-q 127`, and it's a pain, I'd rather do one step.
- marcan_42 5y agoThere are two quality parameters and I'm not sure which one is `-q` in afconvert. One of them is the VBR quality, `kAudioCodecPropertySoundQualityForVBR`. ffmpeg maps it like this: q = 127 - q * 9; So `-q:a 0` should do the same thing as passing 127 to AT. There is another property though; an actual control of codec effort (`kAudioConverterCodecQuality`). That one should be accessible as `aac_at_quality` and maps 0 to 96, so there's no way to go up to the max of 127... But Apple defines "High" as 96, so I get the feeling there won't be a big difference between that and max, especially for an audio codec.
- Wowfunhappy 5y agoThank you, this is the best explanation I've gotten in years! > That one should be accessible as `aac_at_quality` and maps 0 to 96, so there's no way to go up to the max of 127. Is this a bug I should report to ffmpeg?
- marcan_42 5y agoIf there is a nontrivial file size or quality difference between those two settings, sure. If not, it's probably not worth it :)