These are all 44.1kHz and adding -b 4608 helped,
but ffmpeg still does better than flac for this handful of files.
At 09:07 AM 9/27/2022, Martijn van Beurden wrote:
Op di 27 sep. 2022 om 14:22 schreef Michael D.
Lawler <<mailto:[email protected]>[email protected]>:
My conclusion is that ffmpeg's library is doing something that -e
does, but not using a lot of CPU so perhaps this could be studied and
flac could be updated to improve compression further with reasonable
CPU usage. I have all of the files and could provide the ones where
-e is necessary and the few where ffmpeg still does better with -8pe
--lax -l 32.
One important difference between libflac and
ffmpeg is that they use different blocksizes.
FLAC as you've used it will default to blocksize
4096 no matter what sample rate the input is.
ffmpeg will adapt its blocksize to the
samplerate. For 44.1kHz and 48kHz, it uses
blocksize 4608. In the past it has been shown
this benefits certain kinds of music, but the
4096 used by libflac does better for others.
ffmpeg uses a larger blocksize for higher
samplerates and a smaller blocksize for lower
samplerates. This might be the reason you're seeing this difference.
Perhaps you can find out what the sample rates
are of the files that ffmpeg compresses better
than libflac. If those are mainly 44.1kHz or
48kHz, you can try to improve on it with libFALC by adding -b 4608
Kind regards, Martijn van Beurden
--
Michael D. Lawler
email mailto:[email protected]
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