chromium/third_party/webrtc/common_audio/include/audio_util.h

/*
 *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_
#define COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_

#include <stdint.h>

#include <algorithm>
#include <cmath>
#include <cstring>
#include <limits>

#include "api/audio/audio_view.h"
#include "rtc_base/checks.h"

namespace webrtc {

limits_int16;

// TODO(tommi, peah): Move these constants to their own header, e.g.
// `audio_constants.h`. Also consider if they should be in api/.

// Absolute highest acceptable sample rate supported for audio processing,
// capture and codecs. Note that for some components some cases a lower limit
// applies which typically is 48000 but in some cases is lower.
constexpr int kMaxSampleRateHz = …;

// Number of samples per channel for 10ms of audio at the highest sample rate.
constexpr size_t kMaxSamplesPerChannel10ms = …;

// The conversion functions use the following naming convention:
// S16:      int16_t [-32768, 32767]
// Float:    float   [-1.0, 1.0]
// FloatS16: float   [-32768.0, 32768.0]
// Dbfs: float [-20.0*log(10, 32768), 0] = [-90.3, 0]
// The ratio conversion functions use this naming convention:
// Ratio: float (0, +inf)
// Db: float (-inf, +inf)
static inline float S16ToFloat(int16_t v) { … }

static inline int16_t FloatS16ToS16(float v) { … }

static inline int16_t FloatToS16(float v) { … }

static inline float FloatToFloatS16(float v) { … }

static inline float FloatS16ToFloat(float v) { … }

void FloatToS16(const float* src, size_t size, int16_t* dest);
void S16ToFloat(const int16_t* src, size_t size, float* dest);
void S16ToFloatS16(const int16_t* src, size_t size, float* dest);
void FloatS16ToS16(const float* src, size_t size, int16_t* dest);
void FloatToFloatS16(const float* src, size_t size, float* dest);
void FloatS16ToFloat(const float* src, size_t size, float* dest);

inline float DbToRatio(float v) { … }

inline float DbfsToFloatS16(float v) { … }

inline float FloatS16ToDbfs(float v) { … }

// Copy audio from `src` channels to `dest` channels unless `src` and `dest`
// point to the same address. `src` and `dest` must have the same number of
// channels, and there must be sufficient space allocated in `dest`.
// TODO: b/335805780 - Accept ArrayView.
template <typename T>
void CopyAudioIfNeeded(const T* const* src,
                       int num_frames,
                       int num_channels,
                       T* const* dest) { … }

// Deinterleave audio from `interleaved` to the channel buffers pointed to
// by `deinterleaved`. There must be sufficient space allocated in the
// `deinterleaved` buffers (`num_channel` buffers with `samples_per_channel`
// per buffer).
template <typename T>
void Deinterleave(const InterleavedView<const T>& interleaved,
                  const DeinterleavedView<T>& deinterleaved) { … }

// Interleave audio from the channel buffers pointed to by `deinterleaved` to
// `interleaved`. There must be sufficient space allocated in `interleaved`
// (`samples_per_channel` * `num_channels`).
template <typename T>
void Interleave(const DeinterleavedView<const T>& deinterleaved,
                const InterleavedView<T>& interleaved) { … }

// Downmixes an interleaved multichannel signal to a single channel by averaging
// all channels.
// TODO: b/335805780 - Accept InterleavedView and DeinterleavedView.
template <typename T, typename Intermediate>
void DownmixInterleavedToMonoImpl(const T* interleaved,
                                  size_t num_frames,
                                  int num_channels,
                                  T* deinterleaved) { … }

// TODO: b/335805780 - Accept InterleavedView and DeinterleavedView.
template <typename T>
void DownmixInterleavedToMono(const T* interleaved,
                              size_t num_frames,
                              int num_channels,
                              T* deinterleaved);

// TODO: b/335805780 - Accept InterleavedView and DeinterleavedView.
template <>
void DownmixInterleavedToMono<int16_t>(const int16_t* interleaved,
                                       size_t num_frames,
                                       int num_channels,
                                       int16_t* deinterleaved);

}  // namespace webrtc

#endif  // COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_