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audioconvert: add triangular dither

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This commit is contained in:
Wim Taymans 2022-07-11 16:28:51 +02:00
parent 9a5a71dda9
commit 277addcca6
2 changed files with 20 additions and 3 deletions
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9
spa/plugins/audioconvert/fmt-ops-c.c
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@ -236,8 +236,13 @@ static inline void update_dither_c(struct convert *conv, uint32_t n_samples)
float *dither = conv->dither, scale = conv->scale;
uint32_t *state = &conv->random[0];
for (n = 0; n < n_samples; n++)
dither[n] = lcnoise(state) * scale;
if (conv->method < DITHER_METHOD_TRIANGULAR) {
for (n = 0; n < n_samples; n++)
dither[n] = lcnoise(state) * scale;
} else {
for (n = 0; n < n_samples; n++)
dither[n] = (lcnoise(state) + lcnoise(state)) * scale;
}
}
#define MAKE_D_dither(dname,dtype,func) \

14
spa/plugins/audioconvert/fmt-ops-sse2.c
View file

@ -571,7 +571,7 @@ static inline void update_dither_sse2(struct convert *conv, uint32_t n_samples)
const uint32_t *r = SPA_PTR_ALIGN(conv->random, 16, uint32_t);
float *dither = SPA_PTR_ALIGN(conv->dither, 16, float);
__m128 scale = _mm_set1_ps(conv->scale), out[1];
__m128i in[1], t[1];
__m128i in[2], t[1];
for (n = 0; n < n_samples; n += 4) {
/* 32 bit xorshift PRNG, see https://en.wikipedia.org/wiki/Xorshift */
@ -584,6 +584,18 @@ static inline void update_dither_sse2(struct convert *conv, uint32_t n_samples)
in[0] = _mm_xor_si128(in[0], t[0]);
_mm_store_si128((__m128i*)r, in[0]);
if (conv->method >= DITHER_METHOD_TRIANGULAR) {
in[1] = _mm_load_si128((__m128i*)r);
t[0] = _mm_slli_epi32(in[1], 13);
in[1] = _mm_xor_si128(in[1], t[0]);
t[0] = _mm_srli_epi32(in[1], 17);
in[1] = _mm_xor_si128(in[1], t[0]);
t[0] = _mm_slli_epi32(in[1], 5);
in[1] = _mm_xor_si128(in[1], t[0]);
_mm_store_si128((__m128i*)r, in[1]);
in[0] = _mm_add_epi32(in[0], in[1]);
}
out[0] = _mm_cvtepi32_ps(in[0]);
out[0] = _mm_mul_ps(out[0], scale);
_mm_store_ps(&dither[n], out[0]);