Hector Martin

Today in "ffmpeg's AAC encoder is still a embarrassment and nobody should ever use it": OBS on Windows using it, at 320kbps, makes music sound like a low bitrate mp3 (metallic hi-hats, etc). No problem with a custom OBS build on Gentoo with libfdk_aac enabled, at *160* kbps.

FDK AAC is not perfect either to be honest. But ffmpeg's internal AAC encoder is not THAT bad on high bitrates, could you provide an example with 320kbps being bad?

This was a live streaming test, so I don't have a recording. I need to investigate exactly what OBS on Windows is doing to replicate the settings standalone, will check tomorrow.

Here's a quick transcode test of the same source (original is a 320k MP3), subtracted from the original. All at 320k. Re-MP3ing with LAME just adds some noise; fdk does a worse job but still ~uniform; ffmpeg completely murders the high-end with whistling. https://mrcn.st/t/lame_vs_fdk_vs_ffmpeg_delta.wav …

Also it seems the ffmpeg aac encode has a 0.5dB gain reduction for some reason. The original song leaks through because of that, bumping up by 0.5dB fixes it.

Looks like most of the issue here was due to the original being very hot (in the stream it would've been lower). Redoing the test with volume reduction...