Encrypted Media: Support Audio Decrypt-Only.

media/filters/audio_renderer_impl.h

 // 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.
 
 // Audio rendering unit utilizing an AudioRendererSink to output data.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread.
 //    This object is created on the render thread.
 // 2. Pipeline thread
@@ skipping 11 matching lines @@
 
 #include <deque>
 
 #include "base/gtest_prod_util.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/audio_renderer.h"
 #include "media/base/audio_renderer_sink.h"
 #include "media/base/buffers.h"
+#include "media/base/decryptor.h"
 #include "media/filters/audio_renderer_algorithm.h"
 
 namespace media {
 
+class AudioDecoderSelector;
 class AudioSplicer;
+class DecryptingDemuxerStream;
 
 class MEDIA_EXPORT AudioRendererImpl
     : public AudioRenderer,
-      NON_EXPORTED_BASE(public media::AudioRendererSink::RenderCallback) {
+      NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
  public:
   // Methods called on Render thread ------------------------------------------
   // An AudioRendererSink is used as the destination for the rendered audio.
-  explicit AudioRendererImpl(media::AudioRendererSink* sink);
+  AudioRendererImpl(AudioRendererSink* sink,
+                    const SetDecryptorReadyCB& set_decryptor_ready_cb);

[scherkus (not reviewing), 2012/12/14 06:39:12]

it's a bit unfortunate to have to pass this in only to create an
AudioDecoderSelector

perhaps one day instead of populating a FilterCollection + passing in an
AudioDecoderList to Initialize(), WMPI et al can populate AudioDecoderSelectors
and pass _that_ in to Initialize()

nothing to change now, but something to think about...

[xhwang, 2012/12/14 07:45:06]

I actually like this idea ;)

[scherkus (not reviewing), 2012/12/14 19:43:45]

...actually I thought about this a bit more.

If we never have more than a single AudioRenderer/VideoRenderer
implementation... couldn't we construct and pass in the list of decoders + cbs
into the constructor instead of Initialize()?

We could rip out more code from Pipeline...

Hmm.....

 
   // Methods called on pipeline thread ----------------------------------------
   // AudioRenderer implementation.
   virtual void Initialize(const scoped_refptr<DemuxerStream>& stream,
                           const AudioDecoderList& decoders,
                           const PipelineStatusCB& init_cb,
                           const StatisticsCB& statistics_cb,
                           const base::Closure& underflow_cb,
                           const TimeCB& time_cb,
                           const base::Closure& ended_cb,
@@ skipping 76 matching lines @@
   // increments |pending_reads_|.
   //
   // Safe to call from any thread.
   void ScheduleRead_Locked();
 
   // Returns true if the data in the buffer is all before
   // |preroll_timestamp_|. This can only return true while
   // in the kPrerolling state.
   bool IsBeforePrerollTime(const scoped_refptr<Buffer>& buffer);
 
-  // Pops the front of |decoders|, assigns it to |decoder_| and then
-  // calls initialize on the new decoder.
-  void InitializeNextDecoder(const scoped_refptr<DemuxerStream>& demuxer_stream,
-                             scoped_ptr<AudioDecoderList> decoders);
+  // Called when |decoder_selector_| selected the |selected_decoder|.
+  // |decrypting_demuxer_stream| was also populated if a DecryptingDemuxerStream
+  // created to help decrypt the encrypted stream.
+  // Note: |decoder_selector| is passed here to keep the AudioDecoderSelector
+  // alive until OnDecoderSelected() finishes.
+  void OnDecoderSelected(
+      scoped_ptr<AudioDecoderSelector> decoder_selector,
+      const scoped_refptr<AudioDecoder>& selected_decoder,
+      const scoped_refptr<DecryptingDemuxerStream>& decrypting_demuxer_stream);
 
-  // Called when |decoder_| initialization completes.
-  // |demuxer_stream| & |decoders| are used if initialization failed and
-  // InitializeNextDecoder() needs to be called again.
-  void OnDecoderInitDone(const scoped_refptr<DemuxerStream>& demuxer_stream,
-                         scoped_ptr<AudioDecoderList> decoders,
-                         PipelineStatus status);
-
-  // Audio decoder.
-  scoped_refptr<AudioDecoder> decoder_;
+  void ResetDecoder(const base::Closure& callback);
 
   scoped_ptr<AudioSplicer> splicer_;
 
   // The sink (destination) for rendered audio.  |sink_| must only be accessed
   // on the pipeline thread (verify with |pipeline_thread_checker_|).  |sink_|
   // must never be called under |lock_| or the 3-way thread bridge between the
   // audio, pipeline, and decoder threads may deadlock.
   scoped_refptr<media::AudioRendererSink> sink_;
 
+  SetDecryptorReadyCB set_decryptor_ready_cb_;
+
+  // These two will be set by AudioDecoderSelector::SelectAudioDecoder().
+  scoped_refptr<AudioDecoder> decoder_;
+  scoped_refptr<DecryptingDemuxerStream> decrypting_demuxer_stream_;
+
   // Ensures certain methods are always called on the pipeline thread.
   base::ThreadChecker pipeline_thread_checker_;
 
   // AudioParameters constructed during Initialize() based on |decoder_|.
   AudioParameters audio_parameters_;
 
   // Callbacks provided during Initialize().
   PipelineStatusCB init_cb_;
   StatisticsCB statistics_cb_;
   base::Closure underflow_cb_;
@@ skipping 68 matching lines @@
   // Variables used only on the audio thread. ---------------------------------
   int actual_frames_per_buffer_;
   scoped_array<uint8> audio_buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_AUDIO_RENDERER_IMPL_H_