src/media/base/audio_bus.cc

// 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.

#include "media/base/audio_bus.h"

#include <limits>

#include "base/logging.h"
#include "media/audio/audio_parameters.h"
#include "media/base/limits.h"

namespace media {

static bool IsAligned(void* ptr) {
  return (reinterpret_cast<uintptr_t>(ptr) &
          (AudioBus::kChannelAlignment - 1)) == 0U;
}

// Calculates the required size for an AudioBus with the given params, sets
// |aligned_frames| to the actual frame length of each channel array.
static int CalculateMemorySizeInternal(int channels, int frames,
                                       int* out_aligned_frames) {
  // Choose a size such that each channel will be aligned by
  // kChannelAlignment when stored in a contiguous block.
  int aligned_frames =
      ((frames * sizeof(float) + AudioBus::kChannelAlignment - 1) &
       ~(AudioBus::kChannelAlignment - 1)) / sizeof(float);

  if (out_aligned_frames)
    *out_aligned_frames = aligned_frames;

  return sizeof(float) * channels * aligned_frames;
}

// |Format| is the destination type, |Fixed| is a type larger than |Format|
// such that operations can be made without overflowing.
template<class Format, class Fixed>
static void FromInterleavedInternal(const void* src, int start_frame,
                                    int frames, AudioBus* dest) {
  const Format* source = static_cast<const Format*>(src);

  static const Fixed kBias = std::numeric_limits<Format>::is_signed ? 0 :
      std::numeric_limits<Format>::max() / 2 + 1;
  static const float kMaxScale = 1.0f / (kBias ? kBias - 1 :
      std::numeric_limits<Format>::max());
  static const float kMinScale = 1.0f / (kBias ? kBias :
      -static_cast<Fixed>(std::numeric_limits<Format>::min()));

  int channels = dest->channels();
  for (int ch = 0; ch < channels; ++ch) {
    float* channel_data = dest->channel(ch);
    for (int i = start_frame, offset = ch; i < start_frame + frames;
         ++i, offset += channels) {
      Fixed v = static_cast<Fixed>(source[offset]) - kBias;
      channel_data[i] = v * (v < 0 ? kMinScale : kMaxScale);
    }
  }
}

// |Format| is the destination type, |Fixed| is a type larger than |Format|
// such that operations can be made without overflowing.
template<class Format, class Fixed>
static void ToInterleavedInternal(const AudioBus* source, int start_frame,
                                  int frames, void* dst) {
  Format* dest = static_cast<Format*>(dst);

  static const Format kBias = std::numeric_limits<Format>::is_signed ? 0 :
      std::numeric_limits<Format>::max() / 2 + 1;
  static const Fixed kMaxValue = kBias ? kBias - 1 :
      std::numeric_limits<Format>::max();
  static const Fixed kMinValue = kBias ? -kBias :
      std::numeric_limits<Format>::min();

  int channels = source->channels();
  for (int ch = 0; ch < channels; ++ch) {
    const float* channel_data = source->channel(ch);
    for (int i = start_frame, offset = ch; i < frames;
         ++i, offset += channels) {
      float v = channel_data[i];
      Fixed sample = v * (v < 0 ? -kMinValue : kMaxValue);

      if (sample > kMaxValue)
        sample = kMaxValue;
      else if (sample < kMinValue)
        sample = kMinValue;

      dest[offset] = static_cast<Format>(sample) + kBias;
    }
  }
}

static void ValidateConfig(int channels, int frames) {
  CHECK_GT(frames, 0);
  CHECK_GT(channels, 0);
  CHECK_LE(channels, limits::kMaxChannels);
}

static void CheckOverflow(int start_frame, int frames, int total_frames) {
  CHECK_GE(start_frame, 0);
  CHECK_GE(frames, 0);
  CHECK_GT(total_frames, 0);
  int sum = start_frame + frames;
  CHECK_LE(sum, total_frames);
  CHECK_GE(sum, 0);
}

AudioBus::AudioBus(int channels, int frames)
    : frames_(frames),
      can_set_channel_data_(false) {
  ValidateConfig(channels, frames_);

  int aligned_frames = 0;
  int size = CalculateMemorySizeInternal(channels, frames, &aligned_frames);

  data_.reset(static_cast<float*>(base::AlignedAlloc(
      size, AudioBus::kChannelAlignment)));

  BuildChannelData(channels, aligned_frames, data_.get());
}

AudioBus::AudioBus(int channels, int frames, float* data)
    : frames_(frames),
      can_set_channel_data_(false) {
  ValidateConfig(channels, frames_);

  int aligned_frames = 0;
  CalculateMemorySizeInternal(channels, frames, &aligned_frames);

  BuildChannelData(channels, aligned_frames, data);
}

AudioBus::AudioBus(int frames, const std::vector<float*>& channel_data)
    : channel_data_(channel_data),
      frames_(frames),
      can_set_channel_data_(false) {
  ValidateConfig(channel_data_.size(), frames_);

  // Sanity check wrapped vector for alignment and channel count.
  for (size_t i = 0; i < channel_data_.size(); ++i)
    DCHECK(IsAligned(channel_data_[i]));
}

AudioBus::AudioBus(int channels)
    : channel_data_(channels),
      frames_(0),
      can_set_channel_data_(true) {
  for (size_t i = 0; i < channel_data_.size(); ++i)
    channel_data_[i] = NULL;
}

AudioBus::~AudioBus() {}

scoped_ptr<AudioBus> AudioBus::Create(int channels, int frames) {
  return scoped_ptr<AudioBus>(new AudioBus(channels, frames));
}

scoped_ptr<AudioBus> AudioBus::Create(const AudioParameters& params) {
  return scoped_ptr<AudioBus>(new AudioBus(
      params.channels(), params.frames_per_buffer()));
}

#if defined(__LB_SHELL__) || defined(COBALT)

scoped_ptr<AudioBus> AudioBus::Create(int channels, int frames_per_channel,
                                      int bytes_per_frame, bool interleaved) {
  // AudioBus treats everything in float so we have to convert.
  uint32 float_frame_per_channel =
      frames_per_channel * bytes_per_frame / sizeof(float);
  if (interleaved)
    return Create(1, channels * float_frame_per_channel);

  return Create(channels, float_frame_per_channel);
}

#endif  // defined(__LB_SHELL__) || defined(COBALT)

scoped_ptr<AudioBus> AudioBus::CreateWrapper(int channels) {
  return scoped_ptr<AudioBus>(new AudioBus(channels));
}

scoped_ptr<AudioBus> AudioBus::WrapVector(
    int frames, const std::vector<float*>& channel_data) {
  return scoped_ptr<AudioBus>(new AudioBus(frames, channel_data));
}

scoped_ptr<AudioBus> AudioBus::WrapMemory(int channels, int frames,
                                          void* data) {
  // |data| must be aligned by AudioBus::kChannelAlignment.
  CHECK(IsAligned(data));
  return scoped_ptr<AudioBus>(new AudioBus(
      channels, frames, static_cast<float*>(data)));
}

scoped_ptr<AudioBus> AudioBus::WrapMemory(const AudioParameters& params,
                                          void* data) {
  // |data| must be aligned by AudioBus::kChannelAlignment.
  CHECK(IsAligned(data));
  return scoped_ptr<AudioBus>(new AudioBus(
      params.channels(), params.frames_per_buffer(),
      static_cast<float*>(data)));
}

void AudioBus::SetChannelData(int channel, float* data) {
  CHECK(can_set_channel_data_);
  CHECK_GE(channel, 0);
  CHECK_LT(static_cast<size_t>(channel), channel_data_.size());
  DCHECK(IsAligned(data));
  channel_data_[channel] = data;
}

void AudioBus::set_frames(int frames) {
  CHECK(can_set_channel_data_);
  frames_ = frames;
}

void AudioBus::ZeroFramesPartial(int start_frame, int frames) {
  CheckOverflow(start_frame, frames, frames_);

  if (frames <= 0)
    return;

  for (size_t i = 0; i < channel_data_.size(); ++i) {
    memset(channel_data_[i] + start_frame, 0,
           frames * sizeof(*channel_data_[i]));
  }
}

void AudioBus::ZeroFrames(int frames) {
  ZeroFramesPartial(0, frames);
}

void AudioBus::Zero() {
  ZeroFrames(frames_);
}

int AudioBus::CalculateMemorySize(const AudioParameters& params) {
  return CalculateMemorySizeInternal(
      params.channels(), params.frames_per_buffer(), NULL);
}

int AudioBus::CalculateMemorySize(int channels, int frames) {
  return CalculateMemorySizeInternal(channels, frames, NULL);
}

void AudioBus::BuildChannelData(int channels, int aligned_frames, float* data) {
  DCHECK(IsAligned(data));
  DCHECK_EQ(channel_data_.size(), 0U);
  // Separate audio data out into channels for easy lookup later.  Figure out
  channel_data_.reserve(channels);
  for (int i = 0; i < channels; ++i)
    channel_data_.push_back(data + i * aligned_frames);
}

// TODO(dalecurtis): See if intrinsic optimizations help any here.
void AudioBus::FromInterleavedPartial(const void* source, int start_frame,
                                      int frames, int bytes_per_sample) {
  CheckOverflow(start_frame, frames, frames_);
  switch (bytes_per_sample) {
    case 1:
      FromInterleavedInternal<uint8, int16>(source, start_frame, frames, this);
      break;
    case 2:
      FromInterleavedInternal<int16, int32>(source, start_frame, frames, this);
      break;
    case 4:
      FromInterleavedInternal<int32, int64>(source, start_frame, frames, this);
      break;
    default:
      NOTREACHED() << "Unsupported bytes per sample encountered.";
      ZeroFramesPartial(start_frame, frames);
      return;
  }

  // Don't clear remaining frames if this is a partial deinterleave.
  if (!start_frame) {
    // Zero any remaining frames.
    ZeroFramesPartial(frames, frames_ - frames);
  }
}

void AudioBus::FromInterleaved(const void* source, int frames,
                               int bytes_per_sample) {
  FromInterleavedPartial(source, 0, frames, bytes_per_sample);
}

void AudioBus::ToInterleaved(int frames, int bytes_per_sample,
                             void* dest) const {
  ToInterleavedPartial(0, frames, bytes_per_sample, dest);
}

// TODO(dalecurtis): See if intrinsic optimizations help any here.
void AudioBus::ToInterleavedPartial(int start_frame, int frames,
                                    int bytes_per_sample, void* dest) const {
  CheckOverflow(start_frame, frames, frames_);
  switch (bytes_per_sample) {
    case 1:
      ToInterleavedInternal<uint8, int16>(this, start_frame, frames, dest);
      break;
    case 2:
      ToInterleavedInternal<int16, int32>(this, start_frame, frames, dest);
      break;
    case 4:
      ToInterleavedInternal<int32, int64>(this, start_frame, frames, dest);
      break;
    default:
      NOTREACHED() << "Unsupported bytes per sample encountered.";
      memset(dest, 0, frames * bytes_per_sample);
      return;
  }
}

#if defined(__LB_SHELL__) || defined(COBALT)
void AudioBus::FromInterleavedFloat(const float* source, int frames,
                                    int audio_bus_offset) {
  DCHECK_LE(frames + audio_bus_offset, this->frames());

  while (frames > 0) {
    for (int channel = 0; channel < channels(); ++channel) {
      this->channel(channel)[audio_bus_offset] = *source;
      ++source;
    }
    ++audio_bus_offset;
    --frames;
  }
}

void AudioBus::ToInterleavedFloat(
    int frames, int audio_bus_offset, int extra_channels, float* dest) const {
  DCHECK_LE(frames + audio_bus_offset, this->frames());
  DCHECK_GE(extra_channels, 0);

  while (frames > 0) {
    for (int channel = 0; channel < channels(); ++channel) {
      *dest = this->channel(channel)[audio_bus_offset];
      ++dest;
    }
    for (int channel = 0; channel < extra_channels; ++channel) {
      *dest = 0.f;
      ++dest;
    }
    ++audio_bus_offset;
    --frames;
  }
}
#endif  // defined(__LB_SHELL__) || defined(COBALT)

void AudioBus::CopyTo(AudioBus* dest) const {
  CHECK_EQ(channels(), dest->channels());
  CHECK_EQ(frames(), dest->frames());

  // Since we don't know if the other AudioBus is wrapped or not (and we don't
  // want to care), just copy using the public channel() accessors.
  for (int i = 0; i < channels(); ++i)
    memcpy(dest->channel(i), channel(i), sizeof(*channel(i)) * frames());
}

}  // namespace media