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author | andrew@webrtc.org <andrew@webrtc.org@4adac7df-926f-26a2-2b94-8c16560cd09d> | 2013-02-13 23:00:49 +0000 |
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committer | andrew@webrtc.org <andrew@webrtc.org@4adac7df-926f-26a2-2b94-8c16560cd09d> | 2013-02-13 23:00:49 +0000 |
commit | a8ef811fe52add24f90973d19a31347226456abc (patch) | |
tree | 33eda267ca8439db9586cd9cda13b65a871fe959 /webrtc/common_audio/resampler/sinc_resampler.cc | |
parent | 9c4e662ea866e4a108e30f8a31a746a4eb453005 (diff) | |
download | webrtc-a8ef811fe52add24f90973d19a31347226456abc.tar.gz |
Import SincResampler from Chromium.
Committing the originals to make further reviews cleaner.
TBR=bjornv
BUG=webrtc:1395
Review URL: https://webrtc-codereview.appspot.com/1096010
git-svn-id: http://webrtc.googlecode.com/svn/trunk@3508 4adac7df-926f-26a2-2b94-8c16560cd09d
Diffstat (limited to 'webrtc/common_audio/resampler/sinc_resampler.cc')
-rw-r--r-- | webrtc/common_audio/resampler/sinc_resampler.cc | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/webrtc/common_audio/resampler/sinc_resampler.cc b/webrtc/common_audio/resampler/sinc_resampler.cc new file mode 100644 index 0000000000..d836fc7cbc --- /dev/null +++ b/webrtc/common_audio/resampler/sinc_resampler.cc @@ -0,0 +1,347 @@ +// Copyright (c) 2012 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. +// +// Input buffer layout, dividing the total buffer into regions (r0_ - r5_): +// +// |----------------|-----------------------------------------|----------------| +// +// kBlockSize + kKernelSize / 2 +// <---------------------------------------------------------> +// r0_ +// +// kKernelSize / 2 kKernelSize / 2 kKernelSize / 2 kKernelSize / 2 +// <---------------> <---------------> <---------------> <---------------> +// r1_ r2_ r3_ r4_ +// +// kBlockSize +// <---------------------------------------> +// r5_ +// +// The algorithm: +// +// 1) Consume input frames into r0_ (r1_ is zero-initialized). +// 2) Position kernel centered at start of r0_ (r2_) and generate output frames +// until kernel is centered at start of r4_ or we've finished generating all +// the output frames. +// 3) Copy r3_ to r1_ and r4_ to r2_. +// 4) Consume input frames into r5_ (zero-pad if we run out of input). +// 5) Goto (2) until all of input is consumed. +// +// Note: we're glossing over how the sub-sample handling works with +// |virtual_source_idx_|, etc. + +// MSVC++ requires this to be set before any other includes to get M_PI. +#define _USE_MATH_DEFINES + +#include "media/base/sinc_resampler.h" + +#include <cmath> + +#include "base/cpu.h" +#include "base/logging.h" +#include "build/build_config.h" + +#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__) +#include <xmmintrin.h> +#endif + +#if defined(ARCH_CPU_ARM_FAMILY) && defined(USE_NEON) +#include <arm_neon.h> +#endif + +namespace media { + +namespace { + +enum { + // The kernel size can be adjusted for quality (higher is better) at the + // expense of performance. Must be a multiple of 32. + // TODO(dalecurtis): Test performance to see if we can jack this up to 64+. + kKernelSize = 32, + + // The number of destination frames generated per processing pass. Affects + // how often and for how much SincResampler calls back for input. Must be + // greater than kKernelSize. + kBlockSize = 512, + + // The kernel offset count is used for interpolation and is the number of + // sub-sample kernel shifts. Can be adjusted for quality (higher is better) + // at the expense of allocating more memory. + kKernelOffsetCount = 32, + kKernelStorageSize = kKernelSize * (kKernelOffsetCount + 1), + + // The size (in samples) of the internal buffer used by the resampler. + kBufferSize = kBlockSize + kKernelSize +}; + +} // namespace + +const int SincResampler::kMaximumLookAheadSize = kBufferSize; + +SincResampler::SincResampler(double io_sample_rate_ratio, const ReadCB& read_cb) + : io_sample_rate_ratio_(io_sample_rate_ratio), + virtual_source_idx_(0), + buffer_primed_(false), + read_cb_(read_cb), + // Create input buffers with a 16-byte alignment for SSE optimizations. + kernel_storage_(static_cast<float*>( + base::AlignedAlloc(sizeof(float) * kKernelStorageSize, 16))), + input_buffer_(static_cast<float*>( + base::AlignedAlloc(sizeof(float) * kBufferSize, 16))), + // Setup various region pointers in the buffer (see diagram above). + r0_(input_buffer_.get() + kKernelSize / 2), + r1_(input_buffer_.get()), + r2_(r0_), + r3_(r0_ + kBlockSize - kKernelSize / 2), + r4_(r0_ + kBlockSize), + r5_(r0_ + kKernelSize / 2) { + // Ensure kKernelSize is a multiple of 32 for easy SSE optimizations; causes + // r0_ and r5_ (used for input) to always be 16-byte aligned by virtue of + // input_buffer_ being 16-byte aligned. + DCHECK_EQ(kKernelSize % 32, 0) << "kKernelSize must be a multiple of 32!"; + DCHECK_GT(kBlockSize, kKernelSize) + << "kBlockSize must be greater than kKernelSize!"; + // Basic sanity checks to ensure buffer regions are laid out correctly: + // r0_ and r2_ should always be the same position. + DCHECK_EQ(r0_, r2_); + // r1_ at the beginning of the buffer. + DCHECK_EQ(r1_, input_buffer_.get()); + // r1_ left of r2_, r2_ left of r5_ and r1_, r2_ size correct. + DCHECK_EQ(r2_ - r1_, r5_ - r2_); + // r3_ left of r4_, r5_ left of r0_ and r3_ size correct. + DCHECK_EQ(r4_ - r3_, r5_ - r0_); + // r3_, r4_ size correct and r4_ at the end of the buffer. + DCHECK_EQ(r4_ + (r4_ - r3_), r1_ + kBufferSize); + // r5_ size correct and at the end of the buffer. + DCHECK_EQ(r5_ + kBlockSize, r1_ + kBufferSize); + + memset(kernel_storage_.get(), 0, + sizeof(*kernel_storage_.get()) * kKernelStorageSize); + memset(input_buffer_.get(), 0, sizeof(*input_buffer_.get()) * kBufferSize); + + InitializeKernel(); +} + +SincResampler::~SincResampler() {} + +void SincResampler::InitializeKernel() { + // Blackman window parameters. + static const double kAlpha = 0.16; + static const double kA0 = 0.5 * (1.0 - kAlpha); + static const double kA1 = 0.5; + static const double kA2 = 0.5 * kAlpha; + + // |sinc_scale_factor| is basically the normalized cutoff frequency of the + // low-pass filter. + double sinc_scale_factor = + io_sample_rate_ratio_ > 1.0 ? 1.0 / io_sample_rate_ratio_ : 1.0; + + // The sinc function is an idealized brick-wall filter, but since we're + // windowing it the transition from pass to stop does not happen right away. + // So we should adjust the low pass filter cutoff slightly downward to avoid + // some aliasing at the very high-end. + // TODO(crogers): this value is empirical and to be more exact should vary + // depending on kKernelSize. + sinc_scale_factor *= 0.9; + + // Generates a set of windowed sinc() kernels. + // We generate a range of sub-sample offsets from 0.0 to 1.0. + for (int offset_idx = 0; offset_idx <= kKernelOffsetCount; ++offset_idx) { + double subsample_offset = + static_cast<double>(offset_idx) / kKernelOffsetCount; + + for (int i = 0; i < kKernelSize; ++i) { + // Compute the sinc with offset. + double s = + sinc_scale_factor * M_PI * (i - kKernelSize / 2 - subsample_offset); + double sinc = (!s ? 1.0 : sin(s) / s) * sinc_scale_factor; + + // Compute Blackman window, matching the offset of the sinc(). + double x = (i - subsample_offset) / kKernelSize; + double window = kA0 - kA1 * cos(2.0 * M_PI * x) + kA2 + * cos(4.0 * M_PI * x); + + // Window the sinc() function and store at the correct offset. + kernel_storage_.get()[i + offset_idx * kKernelSize] = sinc * window; + } + } +} + +void SincResampler::Resample(float* destination, int frames) { + int remaining_frames = frames; + + // Step (1) -- Prime the input buffer at the start of the input stream. + if (!buffer_primed_) { + read_cb_.Run(r0_, kBlockSize + kKernelSize / 2); + buffer_primed_ = true; + } + + // Step (2) -- Resample! + while (remaining_frames) { + while (virtual_source_idx_ < kBlockSize) { + // |virtual_source_idx_| lies in between two kernel offsets so figure out + // what they are. + int source_idx = static_cast<int>(virtual_source_idx_); + double subsample_remainder = virtual_source_idx_ - source_idx; + + double virtual_offset_idx = subsample_remainder * kKernelOffsetCount; + int offset_idx = static_cast<int>(virtual_offset_idx); + + // We'll compute "convolutions" for the two kernels which straddle + // |virtual_source_idx_|. + float* k1 = kernel_storage_.get() + offset_idx * kKernelSize; + float* k2 = k1 + kKernelSize; + + // Initialize input pointer based on quantized |virtual_source_idx_|. + float* input_ptr = r1_ + source_idx; + + // Figure out how much to weight each kernel's "convolution". + double kernel_interpolation_factor = virtual_offset_idx - offset_idx; + *destination++ = Convolve( + input_ptr, k1, k2, kernel_interpolation_factor); + + // Advance the virtual index. + virtual_source_idx_ += io_sample_rate_ratio_; + + if (!--remaining_frames) + return; + } + + // Wrap back around to the start. + virtual_source_idx_ -= kBlockSize; + + // Step (3) Copy r3_ to r1_ and r4_ to r2_. + // This wraps the last input frames back to the start of the buffer. + memcpy(r1_, r3_, sizeof(*input_buffer_.get()) * (kKernelSize / 2)); + memcpy(r2_, r4_, sizeof(*input_buffer_.get()) * (kKernelSize / 2)); + + // Step (4) + // Refresh the buffer with more input. + read_cb_.Run(r5_, kBlockSize); + } +} + +int SincResampler::ChunkSize() { + return kBlockSize / io_sample_rate_ratio_; +} + +void SincResampler::Flush() { + virtual_source_idx_ = 0; + buffer_primed_ = false; + memset(input_buffer_.get(), 0, sizeof(*input_buffer_.get()) * kBufferSize); +} + +float SincResampler::Convolve(const float* input_ptr, const float* k1, + const float* k2, + double kernel_interpolation_factor) { + // Rely on function level static initialization to keep ConvolveProc selection + // thread safe. + typedef float (*ConvolveProc)(const float* src, const float* k1, + const float* k2, + double kernel_interpolation_factor); +#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__) + static const ConvolveProc kConvolveProc = + base::CPU().has_sse() ? Convolve_SSE : Convolve_C; +#elif defined(ARCH_CPU_ARM_FAMILY) && defined(USE_NEON) + static const ConvolveProc kConvolveProc = Convolve_NEON; +#else + static const ConvolveProc kConvolveProc = Convolve_C; +#endif + + return kConvolveProc(input_ptr, k1, k2, kernel_interpolation_factor); +} + +float SincResampler::Convolve_C(const float* input_ptr, const float* k1, + const float* k2, + double kernel_interpolation_factor) { + float sum1 = 0; + float sum2 = 0; + + // Generate a single output sample. Unrolling this loop hurt performance in + // local testing. + int n = kKernelSize; + while (n--) { + sum1 += *input_ptr * *k1++; + sum2 += *input_ptr++ * *k2++; + } + + // Linearly interpolate the two "convolutions". + return (1.0 - kernel_interpolation_factor) * sum1 + + kernel_interpolation_factor * sum2; +} + +#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__) +float SincResampler::Convolve_SSE(const float* input_ptr, const float* k1, + const float* k2, + double kernel_interpolation_factor) { + // Ensure |k1|, |k2| are 16-byte aligned for SSE usage. Should always be true + // so long as kKernelSize is a multiple of 16. + DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(k1) & 0x0F); + DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(k2) & 0x0F); + + __m128 m_input; + __m128 m_sums1 = _mm_setzero_ps(); + __m128 m_sums2 = _mm_setzero_ps(); + + // Based on |input_ptr| alignment, we need to use loadu or load. Unrolling + // these loops hurt performance in local testing. + if (reinterpret_cast<uintptr_t>(input_ptr) & 0x0F) { + for (int i = 0; i < kKernelSize; i += 4) { + m_input = _mm_loadu_ps(input_ptr + i); + m_sums1 = _mm_add_ps(m_sums1, _mm_mul_ps(m_input, _mm_load_ps(k1 + i))); + m_sums2 = _mm_add_ps(m_sums2, _mm_mul_ps(m_input, _mm_load_ps(k2 + i))); + } + } else { + for (int i = 0; i < kKernelSize; i += 4) { + m_input = _mm_load_ps(input_ptr + i); + m_sums1 = _mm_add_ps(m_sums1, _mm_mul_ps(m_input, _mm_load_ps(k1 + i))); + m_sums2 = _mm_add_ps(m_sums2, _mm_mul_ps(m_input, _mm_load_ps(k2 + i))); + } + } + + // Linearly interpolate the two "convolutions". + m_sums1 = _mm_mul_ps(m_sums1, _mm_set_ps1(1.0 - kernel_interpolation_factor)); + m_sums2 = _mm_mul_ps(m_sums2, _mm_set_ps1(kernel_interpolation_factor)); + m_sums1 = _mm_add_ps(m_sums1, m_sums2); + + // Sum components together. + float result; + m_sums2 = _mm_add_ps(_mm_movehl_ps(m_sums1, m_sums1), m_sums1); + _mm_store_ss(&result, _mm_add_ss(m_sums2, _mm_shuffle_ps( + m_sums2, m_sums2, 1))); + + return result; +} +#endif + +#if defined(ARCH_CPU_ARM_FAMILY) && defined(USE_NEON) +float SincResampler::Convolve_NEON(const float* input_ptr, const float* k1, + const float* k2, + double kernel_interpolation_factor) { + float32x4_t m_input; + float32x4_t m_sums1 = vmovq_n_f32(0); + float32x4_t m_sums2 = vmovq_n_f32(0); + + const float* upper = input_ptr + kKernelSize; + for (; input_ptr < upper; ) { + m_input = vld1q_f32(input_ptr); + input_ptr += 4; + m_sums1 = vmlaq_f32(m_sums1, m_input, vld1q_f32(k1)); + k1 += 4; + m_sums2 = vmlaq_f32(m_sums2, m_input, vld1q_f32(k2)); + k2 += 4; + } + + // Linearly interpolate the two "convolutions". + m_sums1 = vmlaq_f32( + vmulq_f32(m_sums1, vmovq_n_f32(1.0 - kernel_interpolation_factor)), + m_sums2, vmovq_n_f32(kernel_interpolation_factor)); + + // Sum components together. + float32x2_t m_half = vadd_f32(vget_high_f32(m_sums1), vget_low_f32(m_sums1)); + return vget_lane_f32(vpadd_f32(m_half, m_half), 0); +} +#endif + +} // namespace media |