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// Copyright (c) 2010 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.
#ifndef MEDIA_AUDIO_AUDIO_UTIL_H_
#define MEDIA_AUDIO_AUDIO_UTIL_H_
#include <vector>
#include "base/basictypes.h"
namespace media {
// For all audio functions 3 audio formats are supported:
// 8 bits unsigned 0 to 255.
// 16 bit signed (little endian).
// 32 bit signed (little endian)
// AdjustVolume() does a software volume adjustment of a sample buffer.
// The samples are multiplied by the volume, which should range from
// 0.0 (mute) to 1.0 (full volume).
// Using software allows each audio and video to have its own volume without
// affecting the master volume.
// In the future the function may be used to adjust the sample format to
// simplify hardware requirements and to support a wider variety of input
// formats.
// The buffer is modified in-place to avoid memory management, as this
// function may be called in performance critical code.
bool AdjustVolume(void* buf,
size_t buflen,
int channels,
int bytes_per_sample,
float volume);
// FoldChannels() does a software multichannel folding down to stereo.
// Channel order is assumed to be 5.1 Dolby standard which is
// front left, front right, center, surround left, surround right.
// The subwoofer is ignored.
// 6.1 adds a rear center speaker, and 7.1 has 2 rear speakers. These
// channels are rare and ignored.
// After summing the channels, volume is adjusted and the samples are
// clipped to the maximum value.
// Volume should normally range from 0.0 (mute) to 1.0 (full volume), but
// since clamping is performed a value of more than 1 is allowed to increase
// volume.
// The buffer is modified in-place to avoid memory management, as this
// function may be called in performance critical code.
bool FoldChannels(void* buf,
size_t buflen,
int channels,
int bytes_per_sample,
float volume);
// DeinterleaveAudioChannel() takes interleaved audio buffer |source|
// of the given |sample_fmt| and |number_of_channels| and extracts
// |number_of_frames| data for the given |channel_index| and
// puts it in the floating point |destination|.
// It returns |true| on success, or |false| if the |sample_fmt| is
// not recognized.
bool DeinterleaveAudioChannel(void* source,
float* destination,
int channels,
int channel_index,
int bytes_per_sample,
size_t number_of_frames);
// InterleaveFloatToInt16 scales, clips, and interleaves the planar
// floating-point audio contained in |source| to the int16 |destination|.
// The floating-point data is in a canonical range of -1.0 -> +1.0.
// The size of the |source| vector determines the number of channels.
// The |destination| buffer is assumed to be large enough to hold the
// result. Thus it must be at least size: number_of_frames * source.size()
void InterleaveFloatToInt16(const std::vector<float*>& source,
int16* destination,
size_t number_of_frames);
// Reorder PCM from AAC layout to Core Audio 5.1 layout.
// TODO(fbarchard): Switch layout when ffmpeg is updated.
template<class Format>
void SwizzleCoreAudioLayout5_1(Format* b, uint32 filled) {
static const int kNumSurroundChannels = 6;
Format aac[kNumSurroundChannels];
for (uint32 i = 0; i < filled; i += sizeof(aac), b += kNumSurroundChannels) {
memcpy(aac, b, sizeof(aac));
b[0] = aac[1]; // L
b[1] = aac[2]; // R
b[2] = aac[0]; // C
b[3] = aac[5]; // LFE
b[4] = aac[3]; // Ls
b[5] = aac[4]; // Rs
}
}
// Returns the default audio hardware sample-rate.
double GetAudioHardwareSampleRate();
} // namespace media
#endif // MEDIA_AUDIO_AUDIO_UTIL_H_
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