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// Copyright 2013 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_ALSA_ALSA_INPUT_H_
#define MEDIA_AUDIO_ALSA_ALSA_INPUT_H_
#include <alsa/asoundlib.h>
#include <string>
#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "media/audio/agc_audio_stream.h"
#include "media/audio/audio_io.h"
#include "media/audio/audio_parameters.h"
namespace media {
class AlsaWrapper;
class AudioManagerBase;
// Provides an input stream for audio capture based on the ALSA PCM interface.
// This object is not thread safe and all methods should be invoked in the
// thread that created the object.
class AlsaPcmInputStream : public AgcAudioStream<AudioInputStream> {
public:
// Pass this to the constructor if you want to attempt auto-selection
// of the audio recording device.
static const char kAutoSelectDevice[];
// Create a PCM Output stream for the ALSA device identified by
// |device_name|. If unsure of what to use for |device_name|, use
// |kAutoSelectDevice|.
AlsaPcmInputStream(AudioManagerBase* audio_manager,
const std::string& device_name,
const AudioParameters& params,
AlsaWrapper* wrapper);
virtual ~AlsaPcmInputStream();
// Implementation of AudioInputStream.
virtual bool Open() OVERRIDE;
virtual void Start(AudioInputCallback* callback) OVERRIDE;
virtual void Stop() OVERRIDE;
virtual void Close() OVERRIDE;
virtual double GetMaxVolume() OVERRIDE;
virtual void SetVolume(double volume) OVERRIDE;
virtual double GetVolume() OVERRIDE;
private:
// Logs the error and invokes any registered callbacks.
void HandleError(const char* method, int error);
// Reads one or more buffers of audio from the device, passes on to the
// registered callback and schedules the next read.
void ReadAudio();
// Recovers from any device errors if possible.
bool Recover(int error);
// Utility function for talking with the ALSA API.
snd_pcm_sframes_t GetCurrentDelay();
// Non-refcounted pointer back to the audio manager.
// The AudioManager indirectly holds on to stream objects, so we don't
// want circular references. Additionally, stream objects live on the audio
// thread, which is owned by the audio manager and we don't want to addref
// the manager from that thread.
AudioManagerBase* audio_manager_;
std::string device_name_;
AudioParameters params_;
int bytes_per_buffer_;
AlsaWrapper* wrapper_;
base::TimeDelta buffer_duration_; // Length of each recorded buffer.
AudioInputCallback* callback_; // Valid during a recording session.
base::TimeTicks next_read_time_; // Scheduled time for next read callback.
snd_pcm_t* device_handle_; // Handle to the ALSA PCM recording device.
snd_mixer_t* mixer_handle_; // Handle to the ALSA microphone mixer.
snd_mixer_elem_t* mixer_element_handle_; // Handle to the capture element.
base::WeakPtrFactory<AlsaPcmInputStream> weak_factory_;
scoped_ptr<uint8[]> audio_buffer_; // Buffer used for reading audio data.
bool read_callback_behind_schedule_;
DISALLOW_COPY_AND_ASSIGN(AlsaPcmInputStream);
};
} // namespace media
#endif // MEDIA_AUDIO_ALSA_ALSA_INPUT_H_
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