[FFmpeg-devel] [PATCH v7 0/3] 32bps FLAC patches

[Paul B Mahol]

On 10/11/22, Martijn van Beurden <mvanb1 at gmail.com> wrote:
> 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
>
> Changes since v5:
> Slimmed down 32 bps fate flac test from 2 to 1 input file. Replaced
> -strict -2 with -strict experimental in fate and encoder warning.
>
> Changes since v6:
> Deduplicated function bodies with preprocessor macros in both
> encoder and decoder, declared variables in loop body where possible
> and changed ff_ctz to ff_ctzll where necessary
>
> 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    | 218 ++++++++++++++++--
>  libavcodec/flacenc.c    | 480 +++++++++++++++++++++++++++++++---------
>  libavcodec/get_bits.h   |  12 +
>  libavcodec/mathops.h    |   9 +
>  libavcodec/put_bits.h   |   7 +
>  libavcodec/put_golomb.h |  14 --
>  tests/fate/flac.mak     |   4 +
>  8 files changed, 602 insertions(+), 146 deletions(-)
>
> --
> 2.30.2
>



If this is OK, will apply soon.