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Commit 34d88af6 authored by David Reid's avatar David Reid
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Remove the passthrough algorithm from the resampler. 

The rationale for this is that it's just useless - just not do
resampling at all if you don't need to!
parent e8428380
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Showing with 2 additions and 138 deletions
research/mal_resampler.h
View file @ 34d88af6
......@@ -5,7 +5,6 @@ This is research into a new resampler for mini_al. Not yet complete.
Requirements:
- Selection of different algorithms. The following at a minimum:
- Passthrough
- Linear with optional filtering
- Sinc
- Floating point pipeline for f32 and fixed point integer pipeline for s16
......@@ -60,9 +59,8 @@ typedef mal_uint64 (* mal_resampler_seek_proc)(mal_resampler* pResampler, mal_ui
typedef enum
{
mal_resampler_algorithm_sinc = 0, /* Default. */
mal_resampler_algorithm_linear, /* Fastest. */
mal_resampler_algorithm_passthrough /* No resampling. */
mal_resampler_algorithm_sinc = 0, /* Default. */
mal_resampler_algorithm_linear, /* Fastest. */
} mal_resampler_algorithm;
typedef enum
......@@ -200,9 +198,6 @@ mal_uint64 mal_resampler_get_expected_output_frame_count(mal_resampler* pResampl
#endif
#ifdef MINI_AL_IMPLEMENTATION
mal_uint64 mal_resampler_read__passthrough(mal_resampler* pResampler, mal_uint64 frameCount, void** ppFrames);
mal_uint64 mal_resampler_seek__passthrough(mal_resampler* pResampler, mal_uint64 frameCount, mal_uint32 options);
mal_uint64 mal_resampler_read__linear(mal_resampler* pResampler, mal_uint64 frameCount, void** ppFrames);
mal_uint64 mal_resampler_seek__linear(mal_resampler* pResampler, mal_uint64 frameCount, mal_uint32 options);
......@@ -263,13 +258,6 @@ mal_result mal_resampler_init(const mal_resampler_config* pConfig, mal_resampler
}
switch (pResampler->config.algorithm) {
case mal_resampler_algorithm_passthrough:
{
pResampler->init = NULL;
pResampler->read = mal_resampler_read__passthrough;
pResampler->seek = mal_resampler_seek__passthrough;
} break;
case mal_resampler_algorithm_linear:
{
pResampler->init = NULL;
......@@ -347,12 +335,6 @@ mal_uint64 mal_resampler_read(mal_resampler* pResampler, mal_uint64 frameCount,
return mal_resampler_seek(pResampler, frameCount, 0);
}
/* Special case for passthrough. That has a specialized function for reading for efficiency. */
if (pResampler->config.algorithm == mal_resampler_algorithm_passthrough) {
return pResampler->read(pResampler, frameCount, ppFrames);
}
return pResampler->read(pResampler, frameCount, ppFrames);
}
......@@ -367,12 +349,6 @@ mal_uint64 mal_resampler_seek(mal_resampler* pResampler, mal_uint64 frameCount,
return 0; /* Nothing to do, so return early. */
}
/* Special case for passthrough. That has a specialized function for reading for efficiency. */
if (pResampler->config.algorithm == mal_resampler_algorithm_passthrough) {
return pResampler->seek(pResampler, frameCount, options);
}
return pResampler->seek(pResampler, frameCount, options);
}
......@@ -411,11 +387,6 @@ double mal_resampler_get_cached_input_time(mal_resampler* pResampler)
return 0; /* Invalid args. */
}
/* Special case for passthrough. Nothing is ever cached. */
if (pResampler->config.algorithm == mal_resampler_algorithm_passthrough) {
return 0;
}
return mal_resampler__calculate_cached_input_time(pResampler);
}
......@@ -430,11 +401,6 @@ double mal_resampler_get_cached_output_time(mal_resampler* pResampler)
return 0; /* Invalid args. */
}
/* Special case for passthrough. Nothing is ever cached. */
if (pResampler->config.algorithm == mal_resampler_algorithm_passthrough) {
return 0;
}
return mal_resampler__calculate_cached_output_time(pResampler);
}
......@@ -449,11 +415,6 @@ mal_uint64 mal_resampler_get_required_input_frame_count(mal_resampler* pResample
return 0;
}
/* Special case for passthrough. */
if (pResampler->config.algorithm == mal_resampler_algorithm_passthrough) {
return outputFrameCount;
}
/* First grab the amount of output time sitting in the cache. */
double cachedOutputTime = mal_resampler__calculate_cached_output_time(pResampler);
if (cachedOutputTime >= outputFrameCount) {
......@@ -488,108 +449,11 @@ mal_uint64 mal_resampler_get_expected_output_frame_count(mal_resampler* pResampl
return 0;
}
/* Special case for passthrough. */
if (pResampler->config.algorithm == mal_resampler_algorithm_passthrough) {
return inputFrameCount;
}
/* What we're actually calculating here is how many whole output frames will be calculated after consuming inputFrameCount + mal_resampler_get_cached_input_time(). */
return (mal_uint64)floor((mal_resampler__calculate_cached_input_time(pResampler) + inputFrameCount) / pResampler->config.ratio);
}
/*
Passthrough
*/
mal_uint64 mal_resampler_read__passthrough(mal_resampler* pResampler, mal_uint64 frameCount, void** ppFrames)
{
mal_assert(pResampler != NULL);
mal_assert(pResampler->config.onRead != NULL);
mal_assert(frameCount > 0);
mal_assert(ppFrames != NULL);
/*
It's tempting to to just call pResampler->config.onRead() and pass in ppFrames directly, however this violates
our requirement that all buffers passed into onRead() are aligned to MAL_SIMD_ALIGNMENT. If any of the ppFrames
buffers are misaligned we need to read into a temporary buffer.
*/
mal_bool32 isOutputBufferAligned = MAL_TRUE;
for (mal_uint32 iChannel = 0; iChannel < pResampler->config.channels; ++iChannel) {
if (((mal_uintptr)ppFrames[iChannel] & (MAL_SIMD_ALIGNMENT-1)) != 0) {
isOutputBufferAligned = MAL_FALSE;
break;
}
}
if (frameCount <= 0xFFFFFFFF && isOutputBufferAligned) {
return pResampler->config.onRead(pResampler, (mal_uint32)frameCount, ppFrames); /* Fast path. */
} else {
MAL_DECLARE_ALIGNED_STACK_BUFFER(float, ppRunningFrames, 4096, pResampler->config.channels);
mal_uint64 totalFramesRead = 0;
while (frameCount > 0) {
mal_uint64 framesToReadNow = (pResampler->config.format == mal_format_f32) ? ppRunningFramesFrameCount : ppRunningFramesFrameCount*2; /* x2 for the s16 frame count because ppRunningFramesFrameCount is based on f32. */
if (framesToReadNow > frameCount) {
framesToReadNow = frameCount;
}
mal_uint32 framesJustRead = pResampler->config.onRead(pResampler, (mal_uint32)framesToReadNow, (void**)ppRunningFrames);
if (framesJustRead == 0) {
break;
}
totalFramesRead += framesJustRead;
frameCount -= framesJustRead;
mal_uint32 bytesJustRead = framesJustRead * mal_get_bytes_per_sample(pResampler->config.format);
for (mal_uint32 iChannel = 0; iChannel < pResampler->config.channels; ++iChannel) {
mal_copy_memory(ppFrames[iChannel], ppRunningFrames[iChannel], bytesJustRead);
ppFrames[iChannel] = mal_offset_ptr(ppFrames[iChannel], bytesJustRead);
}
if (framesJustRead < framesToReadNow) {
break;
}
}
return totalFramesRead;
}
}
mal_uint64 mal_resampler_seek__passthrough(mal_resampler* pResampler, mal_uint64 frameCount, mal_uint32 options)
{
mal_assert(pResampler != NULL);
mal_assert(pResampler->config.onRead != NULL);
mal_assert(frameCount > 0);
if ((options & MAL_RESAMPLER_SEEK_NO_CLIENT_READ) != 0) {
return frameCount; /* No input from onRead(), so just return immediately. */
}
/* Getting here means we need to read from onRead(). In this case we just read into a trash buffer. */
MAL_DECLARE_ALIGNED_STACK_BUFFER(float, trash, 4096, pResampler->config.channels);
mal_uint64 totalFramesRead = 0;
while (frameCount > 0) {
mal_uint64 framesToRead = trashFrameCount;
if (framesToRead > frameCount) {
framesToRead = frameCount;
}
mal_uint64 framesRead = pResampler->config.onRead(pResampler, (mal_uint32)framesToRead, (void**)trash);
totalFramesRead += framesRead;
frameCount -= framesRead;
/* Don't get stuck in a loop if the client returns no samples. */
if (framesRead < framesToRead) {
break;
}
}
return totalFramesRead;
}
/*
Linear
*/
......
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