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Unified Diff: media/audio/linux/pulse_output.h

Issue 7473021: PulseAudio Sound Playback on Linux (Closed) Base URL: http://git.chromium.org/git/chromium.git@trunk
Patch Set: "New buffering scheme, per offline with vrk" Created 9 years, 4 months ago
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Index: media/audio/linux/pulse_output.h
diff --git a/media/audio/linux/pulse_output.h b/media/audio/linux/pulse_output.h
new file mode 100644
index 0000000000000000000000000000000000000000..af8aef551c5d8412f9ec73861d6f900e620f2172
--- /dev/null
+++ b/media/audio/linux/pulse_output.h
@@ -0,0 +1,126 @@
+// Copyright (c) 2011 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 audio output stream based on the PulseAudio asynchronous API.
+//
+// If the stream is successfully opened, Close() must be called before the
+// stream is deleted as Close() is responsible for ensuring resource cleanup
+// occurs.
+//
+// This object is designed so that all AudioOutputStream methods will be called
+// on the same thread that created the object.
+//
+// WARNING: This object blocks on internal PulseAudio calls after Start() is
+// invoked and repeatedly throughout playback as it waits for PulseAudio write
+// callbacks to occur.
+
+#ifndef MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_
+#define MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_
+
+#include <pulse/pulseaudio.h>
+
+#include <string>
+
+#include "base/message_loop.h"
+#include "base/memory/scoped_ptr.h"
+#include "media/audio/audio_io.h"
+#include "media/audio/audio_parameters.h"
+
+namespace media {
+class SeekableBuffer;
+}
+
+class AudioManagerLinux;
+
+class PulseAudioOutputStream : public AudioOutputStream {
+ public:
+ PulseAudioOutputStream(const AudioParameters& params,
+ AudioManagerLinux* manager,
+ MessageLoop* message_loop);
+
+ virtual ~PulseAudioOutputStream();
+
+ // Implementation of AudioOutputStream.
+ virtual bool Open();
+ virtual void Close();
+ virtual void Start(AudioSourceCallback* callback);
+ virtual void Stop();
+ virtual void SetVolume(double volume);
+ virtual void GetVolume(double* volume);
+
+ private:
+ // PulseAudio Callbacks.
+ static void ContextStateCallback(pa_context* context, void* userdata);
+ static void StreamWriteRequestCallback(pa_stream* stream,
+ size_t length, void* userdata);
+
+ // PulseAudio mainloop iteration loop task function; used to avoid blocking
+ // the audio thread.
+ void WaitForWriteTask();
+
+ // Function to get another packet from the data source and write it into the
+ // client buffer.
+ void BufferPacket();
+ void Write(size_t requested_bytes);
+
+ // API for Proxying calls to the AudioSourceCallback provided during Start().
+ uint32 RunDataCallback(uint8* dest, uint32 max_size,
+ AudioBuffersState buffers_state);
+
+ // Close() helper function to free internal structs.
+ void Reset();
+
+ // Configuration constants from the constructor. Referencable by all threads
+ // since they are constants.
+ const ChannelLayout channel_layout_;
+ const uint32 channel_count_;
+ const pa_sample_format_t sample_format_;
+ const uint32 sample_rate_;
+ const uint32 bytes_per_frame_;
+
+ // Audio manager that created us. Used to report that we've closed.
+ AudioManagerLinux* manager_;
+
+ // PulseAudio API structs.
+ pa_context* pa_context_;
+ pa_mainloop* pa_mainloop_;
+
+ // Handle to the actual PulseAudio playback stream.
+ pa_stream* playback_handle_;
+
+ // Device configuration data. Populated after Open() completes.
+ uint32 packet_size_;
+ uint32 frames_per_packet_;
+
+ // Internal buffer.
+ scoped_ptr<media::SeekableBuffer> client_buffer_;
+ bool source_exhausted_;
+
+ // Float representation of volume from 0.0 to 1.0.
+ float volume_;
+
+ // Flag indicating the code should stop reading from the data source or
+ // writing to the PulseAudio server. This is set because the device has
+ // entered an unrecoverable error state, or the Close() has executed.
+ bool stream_stopped_;
+
+ // Whether or not PulseAudio has called the WriteCallback for the most recent
+ // set of pa_mainloop iterations.
+ bool write_callback_handled_;
+
+ // Message loop used to post WaitForWriteTasks. Used to prevent blocking on
+ // the audio thread while waiting for PulseAudio write callbacks.
+ MessageLoop* message_loop_;
+
+ // Allows us to run tasks on the PulseAudioOutputStream instance which are
+ // bound by its lifetime.
+ ScopedRunnableMethodFactory<PulseAudioOutputStream> method_factory_;
+
+ // Callback to audio data source.
+ AudioSourceCallback* source_callback_;
+
+ DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
+};
+
+#endif // MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_

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