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| author | Lynne <dev@lynne.ee> | 2024-01-29 04:31:43 +0100 |
|---|---|---|
| committer | Lynne <dev@lynne.ee> | 2024-04-27 11:12:07 +0200 |
| commit | 134dba9544f4251ebf5fbbae72f2cddc390ac195 (patch) | |
| tree | ce38b2e35ed54bfba205061a518b02766a669fa2 /libavcodec/opustab.c | |
| parent | a2cdb2f5be065a9da87391e2a5c0ae0051219bad (diff) | |
| download | ffmpeg-134dba9544f4251ebf5fbbae72f2cddc390ac195.tar.gz | |
opusdsp: add ability to modify deemphasis constant
xHE-AAC relies on the same postfilter mechanism
that Opus uses to improve clarity (albeit with a steeper
deemphasis filter).
The code to apply it is identical, it's still just a
simple IIR low-pass filter. This commit makes it possible
to use alternative constants.
Diffstat (limited to 'libavcodec/opustab.c')
| -rw-r--r-- | libavcodec/opustab.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/libavcodec/opustab.c b/libavcodec/opustab.c index 2a57511177..47624fe651 100644 --- a/libavcodec/opustab.c +++ b/libavcodec/opustab.c @@ -1159,3 +1159,31 @@ const uint32_t * const ff_celt_pvq_u_row[15] = { celt_pvq_u + 1207, celt_pvq_u + 1226, celt_pvq_u + 1240, celt_pvq_u + 1248, celt_pvq_u + 1254, celt_pvq_u + 1257 }; + +/* Deemphasis constant (alpha_p), as specified in RFC6716 as 0.8500061035. + * libopus uses a slighly rounded constant, set to 0.85 exactly, + * to simplify its fixed-point version, but it's not significant to impact + * compliance. */ +#define CELT_EMPH_COEFF 0.8500061035f + +DECLARE_ALIGNED(16, const float, ff_opus_deemph_weights)[] = { + CELT_EMPH_COEFF, + CELT_EMPH_COEFF*CELT_EMPH_COEFF, + CELT_EMPH_COEFF*CELT_EMPH_COEFF*CELT_EMPH_COEFF, + CELT_EMPH_COEFF*CELT_EMPH_COEFF*CELT_EMPH_COEFF*CELT_EMPH_COEFF, + + 0, + CELT_EMPH_COEFF, + CELT_EMPH_COEFF*CELT_EMPH_COEFF, + CELT_EMPH_COEFF*CELT_EMPH_COEFF*CELT_EMPH_COEFF, + + 0, + 0, + CELT_EMPH_COEFF, + CELT_EMPH_COEFF*CELT_EMPH_COEFF, + + 0, + 0, + 0, + CELT_EMPH_COEFF, +}; |