Add MediaCodecAudioDecoder implementation

media/filters/android/android_audio_decoder.h

Index: media/filters/android/android_audio_decoder.h
diff --git a/media/filters/android/android_audio_decoder.h b/media/filters/android/android_audio_decoder.h
new file mode 100644
index 0000000000000000000000000000000000000000..6f2362ea755ac3d105029f193d92b4bd1791dea8
--- /dev/null
+++ b/media/filters/android/android_audio_decoder.h
@@ -0,0 +1,172 @@
+// Copyright 2016 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_FILTERS_ANDROID_ANDROID_AUDIO_DECODER_H_
+#define MEDIA_FILTERS_ANDROID_ANDROID_AUDIO_DECODER_H_
+
+#include <deque>
+#include <utility>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "media/base/android/media_codec_bridge.h"
+#include "media/base/android/media_drm_bridge.h"

[qinmin, 2016/02/09 00:31:56]

do we need this here?

[Tima Vaisburd, 2016/02/11 20:23:23]

Removed.

+#include "media/base/audio_decoder.h"
+#include "media/base/audio_decoder_config.h"
+#include "media/base/cdm_context.h"
+#include "media/base/media_export.h"

[qinmin, 2016/02/09 00:31:56]

is this going to be exported?

[Tima Vaisburd, 2016/02/11 20:23:23]

I think not, removed.

+#include "media/base/media_keys.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace media {
+
+// AudioDecoder based on Android's MediaCodec API.
+//
+// It is intended for EME encrypted audio streams which on Android require
+// the MediaCodec API for the playback and coordination with MediaDRM API.
+// Therefore, this decoder is a decrypting decoder: it is able to accept an
+// encrypted as well as non-encrypted stream. The output will be decrypted,
+// if necessary, and decoded.
+
+class MEDIA_EXPORT AndroidAudioDecoder : public AudioDecoder {
+ public:
+  explicit AndroidAudioDecoder(
+      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
+  ~AndroidAudioDecoder() override;
+
+  // AudioDecoder implementation.
+  std::string GetDisplayName() const override;
+  void Initialize(const AudioDecoderConfig& config,
+                  const SetCdmReadyCB& set_cdm_ready_cb,
+                  const InitCB& init_cb,
+                  const OutputCB& output_cb) override;
+  void Decode(const scoped_refptr<DecoderBuffer>& buffer,
+              const DecodeCB& decode_cb) override;
+  void Reset(const base::Closure& closure) override;
+
+ private:
+  // Possible states.
+  enum State {
+    kStateUninitialized,
+    kStateReady,
+    kStateWaitingForKey,
+    kStateDraining,
+    kStateDrained,
+    kStateError,
+  };
+
+  // Information about the MediaCodec's output buffer.
+  struct OutputBufferInfo {
+    int buf_index;
+    size_t offset;
+    size_t size;
+    base::TimeDelta pts;
+    bool is_eos;
+    bool is_key_frame;
+  };
+
+  // Callback called when a new key is available after the codec received
+  // the status MEDIA_CODEC_NO_KEY.
+  void OnKeyAdded();
+
+  // Does the MediaCodec processing cycle: enqueues an input buffer, then
+  // dequeues output buffers.
+  void DoIOTask();
+
+  // Enqueues one pending input buffer into MediaCodec if MediaCodec has a room.
+  // Returns true if any input was processed.
+  bool QueueInput();
+
+  // Dequeues all output buffers from MediaCodec that are immediately available.
+  // Returns true if any output buffer has been received from MediaCodec.
+  bool DequeueOutput();
+
+  // Start or stop our work-polling timer based on whether we did any work, and
+  // how long it has been since we've done work. Should be called within the
+  // timer callback. Calling it with true will start the timer if the timer is
+  // not yet started. The first call with false sets the beginning of idle time,
+  // and subsequent calls with false will eventually stop the timer when the
+  // idle time is large enough.
+  void ManageTimer(bool did_work);
+
+  // Helper method to change the state.
+  void SetState(State new_state);
+
+  // The following helper methods ConfigureMediaCodec(), OnDecodedFrame(),
+  // OnOutputFormatChanged() are specific to the stream (audio/video), but
+  // others seem to apply to any decoder which would be based on MediaCodec.
+  // TODO(timav): refactor the common part out and use it here and in AVDA
+  // (http://crbug.com/583082).
+
+  // Configures |media_codec_| with |config_|. Returns true if the configuration
+  // succeeded.
+  bool ConfigureMediaCodec();
+
+  // Processes the output buffer after it comes from MediaCodec.
+  void OnDecodedFrame(const OutputBufferInfo& out);
+
+  // Processes the output format change.
+  void OnOutputFormatChanged();
+
+  // A helper function for logging.
+  static const char* AsString(State state);
+
+  // Every method is supposed to run on this |task_runner_|.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  // The current state of the object.
+  State state_;
+
+  // The queue of encoded (and maybe encrypted) buffers. The MediaCodec might
+  // not be able to accept the input at the time of Dequeue(), thus all
+  // DecoderBuffers first go to |input_queue_|.
+  using BufferCBPair = std::pair<scoped_refptr<DecoderBuffer>, DecodeCB>;
+  using InputQueue = std::deque<BufferCBPair>;
+  InputQueue input_queue_;
+
+  // Decoder configuration cache.
+  AudioDecoderConfig config_;
+
+  // Frequently used constants derived from |config_|.
+  int channel_count_;
+  int bytes_per_frame_;
+
+  // Callback that reports the end of initialization and its status.
+  InitCB init_cb_;
+
+  // Callback that delivers output frames.
+  OutputCB output_cb_;
+
+  // DecodeCB that should be fired after the decoder has been flashed in case
+  // of EOS.
+  DecodeCB eos_decode_cb_;

[xhwang, 2016/02/08 20:03:34]

Is it possible to replace this with a (null, DecodeCB) in |input_queue_|?

[Tima Vaisburd, 2016/02/11 20:23:23]

It seems there is no need to remove the pair from the |input_queue_| upon
QueueEOS(), it can be done later when EOS comes out in the output buffer. So
this callback seems not needed at all. Removed.

+
+  // The bridge to Android's MediaCodec API.
+  scoped_ptr<MediaCodecBridge> media_codec_;
+
+  // Repeating timer that kicks MediaCodec operation.
+  base::RepeatingTimer io_timer_;
+
+  // Time at which we last did useful work on |io_timer_|.
+  base::TimeTicks idle_time_begin_;

[liberato (no reviews please), 2016/02/08 16:04:36]

i apologize, i didn't press send on friday about this.  please remember that
this is common code from avda, and will be merged back.  comment changes make
sense, but at least comment that this is renamed from the old variable.

also, that means that many of the bad naming / comments in this file are my
doing, so don't blame tima.  :)

+
+  // Index of the dequeued and filled buffer that we keep trying to enqueue.
+  // Such buffer appears in MEDIA_CODEC_NO_KEY processing.
+  int pending_input_buf_index_;
+
+  // Weak pointer factory must be the last member variable.
+  base::WeakPtrFactory<AndroidAudioDecoder> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AndroidAudioDecoder);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_ANDROID_ANDROID_AUDIO_DECODER_H_