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[FFmpeg-devel,v5,0/3] 32bps FLAC patches

Message ID 20220915162145.2284957-1-mvanb1@gmail.com
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Series 32bps FLAC patches | expand

Message

Martijn van Beurden Sept. 15, 2022, 4:21 p.m. UTC 
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(-)