[FFmpeg-devel] [PATCH v5 0/3] 32bps FLAC patches
Martijn van Beurden
mvanb1 at gmail.com
Thu Sep 15 19:21:42 EEST 2022
Recently libFLAC gained the ability (first released in FLAC 1.4.0)
to create FLAC files containing 32-bit int PCM samples. To
keep complexity reasonable, the choice was made to limit residuals
to 32-bit integers, which the encoder must make sure of. In case
the encoder cannot find any predictor of which the residuals fit
this limit, it must default to using a verbatim subframe. Tests have
shown that this does not happen often (<0.1% of subframes on a
music corpus of various styles). See also discussion here:
https://github.com/ietf-wg-cellar/flac-specification/pull/148
These two patches implement decoding and encoding following this
format.
Changes since v1:
fix copy-paste error in encoder, several invocations of
lpc_encode_choose_datapath used wrong parameters, making FATE fail as
compression was less than it should be
Changes since v2:
Rebased decoder part as it didn't apply anymore
Changes since v3:
Moved put_golomb part to flacenc.c (as it is now quite specific to FLAC)
and renamed put_sbits64 to put_sbits63 (and changed assert accordingly)
Changes since v4:
Fix check of decoded_buffer_33bps malloc. Fix reading of wasted bits
for 33bps subframe. Add fate test
Martijn van Beurden (3):
libavcodec/flacdec: Implement decoding of 32 bit-per-sample PCM
libavcodec/flacenc: Implement encoding of 32 bit-per-sample PCM
fate/flac: Add test of 32 bps encoding/decoding
libavcodec/flac.c | 4 +-
libavcodec/flacdec.c | 250 +++++++++++++++++--
libavcodec/flacenc.c | 519 ++++++++++++++++++++++++++++++++--------
libavcodec/get_bits.h | 12 +
libavcodec/mathops.h | 9 +
libavcodec/put_bits.h | 7 +
libavcodec/put_golomb.h | 14 --
tests/fate/flac.mak | 9 +
8 files changed, 684 insertions(+), 140 deletions(-)
--
2.30.2
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