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audioconvert: fix dither scale

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Rectangular dither should be [-0.5, 0.5]
Triangular dither should be [-1.0, 1.0]
Noise should add extra bits.
This commit is contained in:
Wim Taymans 2022-07-11 17:19:28 +02:00
parent e313149f7f
commit 68f883ff77
4 changed files with 23 additions and 3 deletions
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1
spa/plugins/audioconvert/fmt-ops-c.c
View file

@ -237,6 +237,7 @@ static inline void update_dither_c(struct convert *conv, uint32_t n_samples)
uint32_t *state = &conv->random[0];
if (conv->method < DITHER_METHOD_TRIANGULAR) {
scale *= 0.5f;
for (n = 0; n < n_samples; n++)
dither[n] = lcnoise(state) * scale;
} else {

4
spa/plugins/audioconvert/fmt-ops-sse2.c
View file

@ -585,11 +585,12 @@ static inline void update_dither_sse2(struct convert *conv, uint32_t n_samples)
{
uint32_t n;
const uint32_t *r = SPA_PTR_ALIGN(conv->random, 16, uint32_t);
__m128 out[1];
float *dither = SPA_PTR_ALIGN(conv->dither, 16, float);
__m128 scale = _mm_set1_ps(conv->scale), out[1];
__m128i in[2];
if (conv->method < DITHER_METHOD_TRIANGULAR) {
__m128 scale = _mm_set1_ps(conv->scale * 0.5f);
for (n = 0; n < n_samples; n += 4) {
in[0] = _MM_XORSHIFT_EPI32(r);
out[0] = _mm_cvtepi32_ps(_MM_XORSHIFT_EPI32(r));
@ -597,6 +598,7 @@ static inline void update_dither_sse2(struct convert *conv, uint32_t n_samples)
_mm_store_ps(&dither[n], out[0]);
}
} else {
__m128 scale = _mm_set1_ps(conv->scale);
for (n = 0; n < n_samples; n += 4) {
in[0] = _mm_add_epi32( _MM_XORSHIFT_EPI32(r), _MM_XORSHIFT_EPI32(r));
out[0] = _mm_cvtepi32_ps(in[0]);

5
spa/plugins/audioconvert/fmt-ops.c
View file

@ -394,7 +394,10 @@ int convert_init(struct convert *conv)
const struct conv_info *info;
uint32_t i, dither_flags;
conv->scale = 1.0f / (float)(INT32_MAX >> conv->noise);
conv->scale = 1.0f / (float)(INT32_MAX);
if (conv->noise > 0)
conv->scale *= (1 << (conv->noise + 1));
/* disable dither if not needed */
if (!need_dither(conv->dst_fmt))

16
spa/plugins/audioconvert/test-fmt-ops.c
View file

@ -632,6 +632,7 @@ static void run_test_noise(uint32_t fmt, uint32_t noise, uint32_t flags)
const void *ip[N_CHANNELS];
void *op[N_CHANNELS];
uint32_t i, range;
bool all_zero;
spa_zero(conv);
@ -653,35 +654,47 @@ static void run_test_noise(uint32_t fmt, uint32_t noise, uint32_t flags)
range = (1 << conv.noise) - 1;
all_zero = true;
for (i = 0; i < conv.n_channels * N_SAMPLES; i++) {
switch (fmt) {
case SPA_AUDIO_FORMAT_S8:
{
int8_t *d = (int8_t *)samp_out;
if (d[i] != 0)
all_zero = false;
spa_assert_se(SPA_ABS(d[i] - 0) <= (int8_t)range);
break;
}
case SPA_AUDIO_FORMAT_U8:
{
uint8_t *d = (uint8_t *)samp_out;
if (d[i] != 0x80)
all_zero = false;
spa_assert_se((int8_t)SPA_ABS(d[i] - 0x80) <= (int8_t)(range<<1));
break;
}
case SPA_AUDIO_FORMAT_S16:
{
int16_t *d = (int16_t *)samp_out;
if (d[i] != 0)
all_zero = false;
spa_assert_se(SPA_ABS(d[i] - 0) <= (int16_t)range);
break;
}
case SPA_AUDIO_FORMAT_S24:
{
int24_t *d = (int24_t *)samp_out;
spa_assert_se(SPA_ABS(s24_to_s32(d[i]) - 0) <= (int32_t)range);
int32_t t = s24_to_s32(d[i]);
if (t != 0)
all_zero = false;
spa_assert_se(SPA_ABS(t - 0) <= (int32_t)range);
break;
}
case SPA_AUDIO_FORMAT_S32:
{
int32_t *d = (int32_t *)samp_out;
if (d[i] != 0)
all_zero = false;
spa_assert_se(SPA_ABS(d[i] - 0) <= (int32_t)(range << 8));
break;
}
@ -690,6 +703,7 @@ static void run_test_noise(uint32_t fmt, uint32_t noise, uint32_t flags)
break;
}
}
spa_assert_se(all_zero == false);
convert_free(&conv);
}