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VocieProcess/common_audio/include/audio_util.h
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204
VocieProcess/common_audio/include/audio_util.h
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/*
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* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_
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#define COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_
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#include <stdint.h>
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#include <algorithm>
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#include <cmath>
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#include <cstring>
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#include <limits>
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#include "api/audio/audio_view.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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typedef std::numeric_limits<int16_t> limits_int16;
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// TODO(tommi, peah): Move these constants to their own header, e.g.
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// `audio_constants.h`. Also consider if they should be in api/.
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// Absolute highest acceptable sample rate supported for audio processing,
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// capture and codecs. Note that for some components some cases a lower limit
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// applies which typically is 48000 but in some cases is lower.
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constexpr int kMaxSampleRateHz = 384000;
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// Number of samples per channel for 10ms of audio at the highest sample rate.
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constexpr size_t kMaxSamplesPerChannel10ms = kMaxSampleRateHz / 100u;
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// The conversion functions use the following naming convention:
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// S16: int16_t [-32768, 32767]
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// Float: float [-1.0, 1.0]
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// FloatS16: float [-32768.0, 32768.0]
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// Dbfs: float [-20.0*log(10, 32768), 0] = [-90.3, 0]
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// The ratio conversion functions use this naming convention:
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// Ratio: float (0, +inf)
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// Db: float (-inf, +inf)
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static inline float S16ToFloat(int16_t v) {
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constexpr float kScaling = 1.f / 32768.f;
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return v * kScaling;
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}
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static inline int16_t FloatS16ToS16(float v) {
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v = std::min(v, 32767.f);
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v = std::max(v, -32768.f);
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return static_cast<int16_t>(v + std::copysign(0.5f, v));
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}
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static inline int16_t FloatToS16(float v) {
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v *= 32768.f;
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v = std::min(v, 32767.f);
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v = std::max(v, -32768.f);
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return static_cast<int16_t>(v + std::copysign(0.5f, v));
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}
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static inline float FloatToFloatS16(float v) {
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v = std::min(v, 1.f);
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v = std::max(v, -1.f);
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return v * 32768.f;
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}
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static inline float FloatS16ToFloat(float v) {
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v = std::min(v, 32768.f);
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v = std::max(v, -32768.f);
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constexpr float kScaling = 1.f / 32768.f;
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return v * kScaling;
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}
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void FloatToS16(const float* src, size_t size, int16_t* dest);
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void S16ToFloat(const int16_t* src, size_t size, float* dest);
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void S16ToFloatS16(const int16_t* src, size_t size, float* dest);
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void FloatS16ToS16(const float* src, size_t size, int16_t* dest);
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void FloatToFloatS16(const float* src, size_t size, float* dest);
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void FloatS16ToFloat(const float* src, size_t size, float* dest);
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inline float DbToRatio(float v) {
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return std::pow(10.0f, v / 20.0f);
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}
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inline float DbfsToFloatS16(float v) {
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static constexpr float kMaximumAbsFloatS16 = -limits_int16::min();
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return DbToRatio(v) * kMaximumAbsFloatS16;
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}
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inline float FloatS16ToDbfs(float v) {
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RTC_DCHECK_GE(v, 0);
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// kMinDbfs is equal to -20.0 * log10(-limits_int16::min())
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static constexpr float kMinDbfs = -90.30899869919436f;
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if (v <= 1.0f) {
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return kMinDbfs;
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}
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// Equal to 20 * log10(v / (-limits_int16::min()))
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return 20.0f * std::log10(v) + kMinDbfs;
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}
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// Copy audio from `src` channels to `dest` channels unless `src` and `dest`
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// point to the same address. `src` and `dest` must have the same number of
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// channels, and there must be sufficient space allocated in `dest`.
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// TODO: b/335805780 - Accept ArrayView.
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template <typename T>
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void CopyAudioIfNeeded(const T* const* src,
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int num_frames,
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int num_channels,
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T* const* dest) {
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for (int i = 0; i < num_channels; ++i) {
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if (src[i] != dest[i]) {
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std::copy(src[i], src[i] + num_frames, dest[i]);
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}
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}
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}
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// Deinterleave audio from `interleaved` to the channel buffers pointed to
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// by `deinterleaved`. There must be sufficient space allocated in the
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// `deinterleaved` buffers (`num_channel` buffers with `samples_per_channel`
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// per buffer).
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template <typename T>
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void Deinterleave(const InterleavedView<const T>& interleaved,
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const DeinterleavedView<T>& deinterleaved) {
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RTC_DCHECK_EQ(NumChannels(interleaved), NumChannels(deinterleaved));
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RTC_DCHECK_EQ(SamplesPerChannel(interleaved),
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SamplesPerChannel(deinterleaved));
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const auto num_channels = NumChannels(interleaved);
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const auto samples_per_channel = SamplesPerChannel(interleaved);
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for (size_t i = 0; i < num_channels; ++i) {
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MonoView<T> channel = deinterleaved[i];
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size_t interleaved_idx = i;
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for (size_t j = 0; j < samples_per_channel; ++j) {
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channel[j] = interleaved[interleaved_idx];
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interleaved_idx += num_channels;
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}
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}
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}
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// Interleave audio from the channel buffers pointed to by `deinterleaved` to
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// `interleaved`. There must be sufficient space allocated in `interleaved`
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// (`samples_per_channel` * `num_channels`).
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template <typename T>
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void Interleave(const DeinterleavedView<const T>& deinterleaved,
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const InterleavedView<T>& interleaved) {
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RTC_DCHECK_EQ(NumChannels(interleaved), NumChannels(deinterleaved));
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RTC_DCHECK_EQ(SamplesPerChannel(interleaved),
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SamplesPerChannel(deinterleaved));
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for (size_t i = 0; i < deinterleaved.num_channels(); ++i) {
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const auto channel = deinterleaved[i];
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size_t interleaved_idx = i;
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for (size_t j = 0; j < deinterleaved.samples_per_channel(); ++j) {
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interleaved[interleaved_idx] = channel[j];
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interleaved_idx += deinterleaved.num_channels();
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}
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}
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}
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// Downmixes an interleaved multichannel signal to a single channel by averaging
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// all channels.
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// TODO: b/335805780 - Accept InterleavedView and DeinterleavedView.
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template <typename T, typename Intermediate>
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void DownmixInterleavedToMonoImpl(const T* interleaved,
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size_t num_frames,
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int num_channels,
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T* deinterleaved) {
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RTC_DCHECK_GT(num_channels, 0);
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RTC_DCHECK_GT(num_frames, 0);
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const T* const end = interleaved + num_frames * num_channels;
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while (interleaved < end) {
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const T* const frame_end = interleaved + num_channels;
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Intermediate value = *interleaved++;
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while (interleaved < frame_end) {
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value += *interleaved++;
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}
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*deinterleaved++ = value / num_channels;
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}
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}
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// TODO: b/335805780 - Accept InterleavedView and DeinterleavedView.
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template <typename T>
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void DownmixInterleavedToMono(const T* interleaved,
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size_t num_frames,
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int num_channels,
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T* deinterleaved);
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// TODO: b/335805780 - Accept InterleavedView and DeinterleavedView.
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template <>
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void DownmixInterleavedToMono<int16_t>(const int16_t* interleaved,
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size_t num_frames,
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int num_channels,
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int16_t* deinterleaved);
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} // namespace webrtc
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#endif // COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_
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