ffmpeg FLAC 24 bit 96khz to 16 bit 48khz

Question

Trying to figure out ffmpeg, currently working on getting 24bit/96khz FLAC files into 16bit/48khz.

Answer 1

Basic example

ffmpeg -i input.flac -sample_fmt s16 -ar 48000 output.flac

• List sample formats: ffmpeg -sample_fmts
• List additional flac encoding options: ffmpeg -h encoder=flac

aresample filter example

ffmpeg -i input.flac -af aresample=out_sample_fmt=s16:out_sample_rate=48000 output.flac

Either example will result in the same output: you can verify with the hash muxer.

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Changing the dithering method

See the -dither_method option for a list of available dithering methods and additional resampling options. Example:

ffmpeg -i input.flac -dither_method triangular_hp -sample_fmt s16 -ar 48000 output.flac

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SoX resampler

FFmpeg supports two resamplers: the default swresample library, and the external SoX resampler (soxr).

To use soxr your ffmpeg must be compiled with --enable-libsoxr. Then choose it with the -resampler option:

ffmpeg -i input.flac -resampler soxr -sample_fmt s16 -ar 48000 output.flac

Or use the aresample filter to do it all:

ffmpeg -i input.flac -af aresample=resampler=soxr:out_sample_fmt=s16:out_sample_rate=48000 output.flac

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More info

• FFmpeg Resampler Documentation

Answer 2

As a bash script, that produces new files with -16 appended to their names; one could rename then delete the original files easily in the script but I'm a little too paranoid for that.

#!/bin/sh
# requires: ffmpeg
for f in *.flac;
do
echo "Processing $f"
ffmpeg -i "$f" -sample_fmt s16 -ar 48000 "${f%.flac}-16.flac"
done