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// 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.
#ifndef MEDIA_AUDIO_AUDIO_UTIL_H_
#define MEDIA_AUDIO_AUDIO_UTIL_H_
#include <string>
#include "base/basictypes.h"
#include "media/base/channel_layout.h"
#include "media/base/media_export.h"
namespace base {
class SharedMemory;
}
namespace media {
class AudioBus;
// 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.
MEDIA_EXPORT bool AdjustVolume(void* buf,
size_t buflen,
int channels,
int bytes_per_sample,
float volume);
// MixStreams() mixes 2 audio streams with same sample rate and number of
// samples, adjusting volume on one of them.
// Dst += Src * volume.
MEDIA_EXPORT void MixStreams(void* dst,
void* src,
size_t buflen,
int bytes_per_sample,
float volume);
// Returns the default audio output hardware sample-rate.
MEDIA_EXPORT int GetAudioHardwareSampleRate();
// Returns the audio input hardware sample-rate for the specified device.
MEDIA_EXPORT int GetAudioInputHardwareSampleRate(
const std::string& device_id);
// Returns the optimal low-latency buffer size for the audio hardware.
// This is the smallest buffer size the system can comfortably render
// at without glitches. The buffer size is in sample-frames.
MEDIA_EXPORT size_t GetAudioHardwareBufferSize();
// Returns the channel layout for the specified audio input device.
MEDIA_EXPORT ChannelLayout GetAudioInputHardwareChannelLayout(
const std::string& device_id);
// Computes a buffer size based on the given |sample_rate|. Must be used in
// conjunction with AUDIO_PCM_LINEAR.
MEDIA_EXPORT size_t GetHighLatencyOutputBufferSize(int sample_rate);
#if defined(OS_WIN)
// Returns number of buffers to be used by wave out.
MEDIA_EXPORT int NumberOfWaveOutBuffers();
#endif // defined(OS_WIN)
} // namespace media
#endif // MEDIA_AUDIO_AUDIO_UTIL_H_
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