Encrypted Media: Support Audio Decrypt-Only.

media/filters/audio_decoder_selector.h

Index: media/filters/audio_decoder_selector.h
diff --git a/media/filters/audio_decoder_selector.h b/media/filters/audio_decoder_selector.h
new file mode 100644
index 0000000000000000000000000000000000000000..8e2a954ad7bae41cc5c676515775ab40d3180be9
--- /dev/null
+++ b/media/filters/audio_decoder_selector.h
@@ -0,0 +1,84 @@
+// 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.
+
+#ifndef MEDIA_FILTERS_AUDIO_DECODER_SELECTOR_H_
+#define MEDIA_FILTERS_AUDIO_DECODER_SELECTOR_H_
+
+#include <list>
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "media/base/audio_decoder.h"
+#include "media/base/decryptor.h"
+#include "media/base/demuxer_stream.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace media {
+
+class DecoderBuffer;
+class DecryptingDemuxerStream;
+class Decryptor;
+
+// AudioDecoderSelector (creates if necessary and) initializes the proper
+// AudioDecoder for a given DemuxerStream. If the given DemuxerStream is
+// encrypted, a DecryptingDemuxerStream may also be created.
+class MEDIA_EXPORT AudioDecoderSelector {
+ public:
+  typedef std::list<scoped_refptr<AudioDecoder> > AudioDecoderList;
+
+  // Indicates completion of AudioDecoder selection.
+  // - First parameter: The initialized AudioDecoder. If it's set to NULL, then
+  // AudioDecoder initialization failed.
+  // - Second parameter: The initialized DecryptingDemuxerStream. If it's not
+  // NULL, then a DecryptingDemuxerStream is created and initialized to do
+  // decryption for the initialized AudioDecoder.
+  // Note: DecryptingDemuxerStream::Reset() should be called before

[ddorwin, 2012/12/13 23:09:43]

Does the caller own the DDS?
"The caller should call ... before...."

[xhwang, 2012/12/14 03:16:21]

Done.

+  // AudioDecoder::Reset() to release any pending decryption or read.
+  typedef base::Callback<
+      void(const scoped_refptr<AudioDecoder>&,
+           const scoped_refptr<DecryptingDemuxerStream>&)> SelectDecoderCB;
+
+  // If |set_decryptor_ready_cb| is null, no decryptor will be available
+  // to perform decryption. This could happen if --enable-encrypted-media

[scherkus (not reviewing), 2012/12/13 23:39:07]

nit: don't talk about the switch, just say it's an optional parameter and that
decryption will be unavailable if null

[xhwang, 2012/12/14 03:16:21]

Done.

+  // is not set.
+  AudioDecoderSelector(
+      const scoped_refptr<base::MessageLoopProxy>& message_loop,
+      const AudioDecoderList& clear_decoders,

[scherkus (not reviewing), 2012/12/13 23:39:07]

no clue what "clear_decoders" means

why not simply "decoders" ?

[xhwang, 2012/12/14 03:16:21]

Done.

+      const SetDecryptorReadyCB& set_decryptor_ready_cb);
+  ~AudioDecoderSelector();
+
+  void SelectAudioDecoder(const scoped_refptr<DemuxerStream>& stream,
+                          const StatisticsCB& statistics_cb,
+                          const SelectDecoderCB& select_decoder_cb);
+
+ private:
+  void DecryptingAudioDecoderInitDone(PipelineStatus status);
+  void DecryptingDemuxerStreamInitDone(PipelineStatus status);
+  void InitializeNextClearDecoder();

[scherkus (not reviewing), 2012/12/13 23:39:07]

I'm really not finding the usage of "Clear" to be a helpful term here

[xhwang, 2012/12/14 03:16:21]

Done.

+  void ClearDecoderInitDone(PipelineStatus status);
+
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
+  AudioDecoderList clear_decoders_;
+  SetDecryptorReadyCB set_decryptor_ready_cb_;
+
+  scoped_refptr<DemuxerStream> input_stream_;
+  StatisticsCB statistics_cb_;
+  SelectDecoderCB select_decoder_cb_;
+
+  scoped_refptr<AudioDecoder> audio_decoder_;
+  scoped_refptr<DecryptingDemuxerStream> decrypted_stream_;
+
+  base::WeakPtrFactory<AudioDecoderSelector> weak_ptr_factory_;
+  base::WeakPtr<AudioDecoderSelector> weak_this_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioDecoderSelector);

[scherkus (not reviewing), 2012/12/13 23:39:07]

s/C_A_A/IMPLICIT_CONSTRUCTORS/ (since you don't define a default ctor)

[xhwang, 2012/12/14 03:16:21]

Done.

+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_AUDIO_DECODER_SELECTOR_H_