| // 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. |
| // |
| // Creates an output stream based on the cras (ChromeOS audio server) interface. |
| // |
| // CrasOutputStream object is *not* thread-safe and should only be used |
| // from the audio thread. |
| |
| #ifndef MEDIA_AUDIO_LINUX_CRAS_OUTPUT_H_ |
| #define MEDIA_AUDIO_LINUX_CRAS_OUTPUT_H_ |
| |
| #include <alsa/asoundlib.h> |
| #include <cras_client.h> |
| #include <ostream> |
| |
| #include "base/compiler_specific.h" |
| #include "base/gtest_prod_util.h" |
| #include "media/audio/audio_io.h" |
| |
| namespace media { |
| |
| class AudioManagerLinux; |
| class AudioParameters; |
| |
| // Implementation of AudioOuputStream for Chrome OS using the Chrome OS audio |
| // server. |
| class MEDIA_EXPORT CrasOutputStream : public AudioOutputStream { |
| public: |
| // The ctor takes all the usual parameters, plus |manager| which is the |
| // audio manager who is creating this object. |
| CrasOutputStream(const AudioParameters& params, AudioManagerLinux* manager); |
| |
| // The dtor is typically called by the AudioManager only and it is usually |
| // triggered by calling AudioOutputStream::Close(). |
| virtual ~CrasOutputStream(); |
| |
| // Implementation of AudioOutputStream. |
| virtual bool Open() OVERRIDE; |
| virtual void Close() OVERRIDE; |
| virtual void Start(AudioSourceCallback* callback) OVERRIDE; |
| virtual void Stop() OVERRIDE; |
| virtual void SetVolume(double volume) OVERRIDE; |
| virtual void GetVolume(double* volume) OVERRIDE; |
| |
| // Flags indicating the state of the stream. |
| enum InternalState { |
| kInError = 0, |
| kCreated, |
| kIsOpened, |
| kIsPlaying, |
| kIsStopped, |
| kIsClosed |
| }; |
| friend std::ostream& operator<<(std::ostream& os, InternalState); |
| // Reports the current state for unit testing. |
| InternalState state(); |
| |
| private: |
| // Handles requests to put samples in the provided buffer. This will be |
| // called by the audio server when it needs more data. |
| static int PutSamples(cras_client* client, |
| cras_stream_id_t stream_id, |
| uint8* samples, |
| size_t frames, |
| const timespec* sample_ts, |
| void* arg); |
| |
| // Handles notificaiton that there was an error with the playback stream. |
| static int StreamError(cras_client* client, |
| cras_stream_id_t stream_id, |
| int err, |
| void* arg); |
| |
| // Actually fills buffer with audio data. Called from PutSamples(). |
| uint32 Render(size_t frames, uint8* buffer, const timespec* sample_ts); |
| |
| // Deals with an error that occured in the stream. Called from StreamError(). |
| void NotifyStreamError(int err); |
| |
| // Functions to safeguard state transitions. All changes to the object state |
| // should go through these functions. |
| bool CanTransitionTo(InternalState to); |
| InternalState TransitionTo(InternalState to); |
| |
| // The client used to communicate with the audio server. |
| cras_client* client_; |
| |
| // ID of the playing stream. |
| cras_stream_id_t stream_id_; |
| |
| // Packet size in samples. |
| uint32 samples_per_packet_; |
| |
| // Size of frame in bytes. |
| uint32 bytes_per_frame_; |
| |
| // Rate in Hz. |
| size_t frame_rate_; |
| |
| // Number of channels. |
| size_t num_channels_; |
| |
| // PCM format for Alsa. |
| const snd_pcm_format_t pcm_format_; |
| |
| // Current state. |
| InternalState state_; |
| |
| // Volume level from 0.0 to 1.0. |
| float volume_; |
| |
| // Audio manager that created us. Used to report that we've been closed. |
| AudioManagerLinux* manager_; |
| |
| // Callback to get audio samples. |
| AudioSourceCallback* source_callback_; |
| |
| // Container for retrieving data from AudioSourceCallback::OnMoreData(). |
| scoped_ptr<AudioBus> audio_bus_; |
| |
| DISALLOW_COPY_AND_ASSIGN(CrasOutputStream); |
| }; |
| |
| } // namespace media |
| |
| #endif // MEDIA_AUDIO_LINUX_CRAS_OUTPUT_H_ |