Encoding FLAC at 32-bits

[SeeMoreDigital]

From what I understand it should be possible to create FLAC encodes at 32-bits.

However, when I tried creating such an encode (using FFmpeg and UsEac3To) from a 88.2kHz 32-bit PCM source, the bit-depth is automatically reduced to 24-bits!

How can this issue be resolved?

[Busty]

AFAIK, Flac supports 32bit since version 1.4 released about 2022, so maybe check if you are up to date. And it may only support 32bit integer and not floating point.

Did you specify that the output should be 32bit? I'm not an expert on ffmpeg grammar, but there should be something like "s32" that you can enter to tell ffmpeg to encode in 32bit.

[SeeMoreDigital]

Yep, I used the following commandline but the bit-depth was automatically reduced to 24-bits: -

ffmpeg -i input.wav -af aformat=s32:88200 output.flac

EDIT: Ideally I would like to encode from an (SACD) .dff source directly to a FLAC 88.2kHz / 32-bit file. Without the need to encode to PCM first.

[tebasuna51]

Your source is 32 bits int or float?

Flac does not support float samples then 32 float always must be converted to 24 int (same precission) with a normalize peaks first to avoid clips.
Eac3to do fine this job.

If your source is 32 int it was supported in Flac 1.4.0 09 Sep 2022 (https://xiph.org/flac/2022/09/09/flac-1-4-0-released.html) maybe eac3to (old versions or not updated) do the same process first (convert to 24 int).

ffmpeg show:
[flac @ 00000243635cc340] encoding as 24 bits-per-sample, more is considered experimental. Add -strict experimental if you want to encode more than 24 bits-per-sample

But adding -strict experimental work the same: output 24 bits with sources 32 int or float (correct for float but not for int)

Seems both (eac3to and ffmpeg) need be improved.

[SeeMoreDigital]

Thanks for the info Teb,

I can confirm that the following commandline worked perfectly at converting a 32-bit int PCM source and Float CC PCM source to a 32-bit FLAC file.

ffmpeg -i input.wav -strict experimental -af aformat=s32:88200 output.flac


Nice one...