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pcm/PcmMix: improved dithering

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Use the existing PcmDither library.
This commit is contained in:
Max Kellermann 2013-12-28 17:42:03 +01:00
parent afcf0795c4
commit da29298d4d
5 changed files with 48 additions and 25 deletions
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6
src/OutputInternal.hxx
View File

@ -22,6 +22,7 @@
#include "AudioFormat.hxx"
#include "pcm/PcmBuffer.hxx"
#include "pcm/PcmDither.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include "thread/Thread.hxx"
@ -171,6 +172,11 @@ struct audio_output {
*/
PcmBuffer cross_fade_buffer;
/**
* The dithering state for cross-fading two streams.
*/
PcmDither cross_fade_dither;
/**
* The filter object of this audio output. This is an
* instance of chain_filter_plugin.

2
src/OutputThread.cxx
View File

@ -392,7 +392,7 @@ ao_filter_chunk(struct audio_output *ao, const struct music_chunk *chunk,
void *dest = ao->cross_fade_buffer.Get(other_length);
memcpy(dest, other_data, other_length);
if (!pcm_mix(dest, data, length,
if (!pcm_mix(ao->cross_fade_dither, dest, data, length,
ao->in_audio_format.format,
1.0 - chunk->mix_ratio)) {
FormatError(output_domain,

45
src/pcm/PcmMix.cxx
View File

@ -25,41 +25,47 @@
#include "Traits.hxx"
#include "util/Clamp.hxx"
#include "PcmDither.cxx" // including the .cxx file to get inlined templates
#include <assert.h>
#include <math.h>
template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::value_type
PcmAddVolume(typename Traits::value_type _a, typename Traits::value_type _b,
PcmAddVolume(PcmDither &dither,
typename Traits::value_type _a, typename Traits::value_type _b,
int volume1, int volume2)
{
typename Traits::long_type a(_a), b(_b);
typename Traits::long_type c(a * volume1 + b * volume2);
typename Traits::value_type c = ((a * volume1 + b * volume2) +
pcm_volume_dither() + PCM_VOLUME_1S / 2)
/ PCM_VOLUME_1S;
return PcmClamp<F, Traits>(c);
return dither.DitherShift<typename Traits::long_type,
Traits::BITS + PCM_VOLUME_BITS,
Traits::BITS>(c);
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static void
PcmAddVolume(typename Traits::pointer_type a,
PcmAddVolume(PcmDither &dither,
typename Traits::pointer_type a,
typename Traits::const_pointer_type b,
size_t n, int volume1, int volume2)
{
for (size_t i = 0; i != n; ++i)
a[i] = PcmAddVolume<F, Traits>(a[i], b[i], volume1, volume2);
a[i] = PcmAddVolume<F, Traits>(dither, a[i], b[i],
volume1, volume2);
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static void
PcmAddVolumeVoid(void *a, const void *b, size_t size, int volume1, int volume2)
PcmAddVolumeVoid(PcmDither &dither,
void *a, const void *b, size_t size, int volume1, int volume2)
{
constexpr size_t sample_size = Traits::SAMPLE_SIZE;
assert(size % sample_size == 0);
PcmAddVolume<F, Traits>(typename Traits::pointer_type(a),
PcmAddVolume<F, Traits>(dither,
typename Traits::pointer_type(a),
typename Traits::const_pointer_type(b),
size / sample_size,
volume1, volume2);
@ -80,7 +86,7 @@ pcm_add_vol_float(float *buffer1, const float *buffer2,
}
static bool
pcm_add_vol(void *buffer1, const void *buffer2, size_t size,
pcm_add_vol(PcmDither &dither, void *buffer1, const void *buffer2, size_t size,
int vol1, int vol2,
SampleFormat format)
{
@ -91,22 +97,26 @@ pcm_add_vol(void *buffer1, const void *buffer2, size_t size,
return false;
case SampleFormat::S8:
PcmAddVolumeVoid<SampleFormat::S8>(buffer1, buffer2, size,
PcmAddVolumeVoid<SampleFormat::S8>(dither,
buffer1, buffer2, size,
vol1, vol2);
return true;
case SampleFormat::S16:
PcmAddVolumeVoid<SampleFormat::S16>(buffer1, buffer2, size,
PcmAddVolumeVoid<SampleFormat::S16>(dither,
buffer1, buffer2, size,
vol1, vol2);
return true;
case SampleFormat::S24_P32:
PcmAddVolumeVoid<SampleFormat::S24_P32>(buffer1, buffer2, size,
PcmAddVolumeVoid<SampleFormat::S24_P32>(dither,
buffer1, buffer2, size,
vol1, vol2);
return true;
case SampleFormat::S32:
PcmAddVolumeVoid<SampleFormat::S32>(buffer1, buffer2, size,
PcmAddVolumeVoid<SampleFormat::S32>(dither,
buffer1, buffer2, size,
vol1, vol2);
return true;
@ -201,7 +211,7 @@ pcm_add(void *buffer1, const void *buffer2, size_t size,
}
bool
pcm_mix(void *buffer1, const void *buffer2, size_t size,
pcm_mix(PcmDither &dither, void *buffer1, const void *buffer2, size_t size,
SampleFormat format, float portion1)
{
float s;
@ -217,5 +227,6 @@ pcm_mix(void *buffer1, const void *buffer2, size_t size,
int vol1 = s * PCM_VOLUME_1S + 0.5;
vol1 = Clamp<int>(vol1, 0, PCM_VOLUME_1S);
return pcm_add_vol(buffer1, buffer2, size, vol1, PCM_VOLUME_1S - vol1, format);
return pcm_add_vol(dither, buffer1, buffer2, size,
vol1, PCM_VOLUME_1S - vol1, format);
}

4
src/pcm/PcmMix.hxx
View File

@ -25,6 +25,8 @@
#include <stddef.h>
class PcmDither;
/*
* Linearly mixes two PCM buffers. Both must have the same length and
* the same audio format. The formula is:
@ -44,7 +46,7 @@
*/
gcc_warn_unused_result
bool
pcm_mix(void *buffer1, const void *buffer2, size_t size,
pcm_mix(PcmDither &dither, void *buffer1, const void *buffer2, size_t size,
SampleFormat format, float portion1);
#endif

16
test/test_pcm_mix.cxx
View File

@ -21,6 +21,7 @@
#include "test_pcm_all.hxx"
#include "test_pcm_util.hxx"
#include "pcm/PcmMix.hxx"
#include "pcm/PcmDither.hxx"
template<typename T, SampleFormat format, typename G=RandomInt<T>>
static void
@ -30,23 +31,26 @@ TestPcmMix(G g=G())
const auto src1 = TestDataBuffer<T, N>(g);
const auto src2 = TestDataBuffer<T, N>(g);
PcmDither dither;
/* portion1=1.0: result must be equal to src1 */
auto result = src1;
bool success = pcm_mix(result.begin(), src2.begin(), sizeof(result),
bool success = pcm_mix(dither,
result.begin(), src2.begin(), sizeof(result),
format, 1.0);
CPPUNIT_ASSERT(success);
AssertEqualWithTolerance(result, src1, 1);
AssertEqualWithTolerance(result, src1, 3);
/* portion1=0.0: result must be equal to src2 */
result = src1;
success = pcm_mix(result.begin(), src2.begin(), sizeof(result),
success = pcm_mix(dither, result.begin(), src2.begin(), sizeof(result),
format, 0.0);
CPPUNIT_ASSERT(success);
AssertEqualWithTolerance(result, src2, 1);
AssertEqualWithTolerance(result, src2, 3);
/* portion1=0.5 */
result = src1;
success = pcm_mix(result.begin(), src2.begin(), sizeof(result),
success = pcm_mix(dither, result.begin(), src2.begin(), sizeof(result),
format, 0.5);
CPPUNIT_ASSERT(success);
@ -54,7 +58,7 @@ TestPcmMix(G g=G())
for (unsigned i = 0; i < N; ++i)
expected[i] = (int64_t(src1[i]) + int64_t(src2[i])) / 2;
AssertEqualWithTolerance(result, expected, 1);
AssertEqualWithTolerance(result, expected, 3);
}
void