Encrypted Media: Support Audio Decrypt-Only.

media/filters/audio_decoder_selector.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.
+
+#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: The caller owns selected AudioDecoder and DecryptingDemuxerStream.
+  // The caller should call DecryptingDemuxerStream::Reset() before
+  // calling AudioDecoder::Reset() to release any pending decryption or read.
+  typedef base::Callback<
+      void(const scoped_refptr<AudioDecoder>&,
+           const scoped_refptr<DecryptingDemuxerStream>&)> SelectDecoderCB;
+
+  // |set_decryptor_ready_cb| is optional. If |set_decryptor_ready_cb| is null,
+  // no decryptor will be available to perform decryption.
+  AudioDecoderSelector(
+      const scoped_refptr<base::MessageLoopProxy>& message_loop,
+      const AudioDecoderList& decoders,
+      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 InitializeNextDecoder();
+  void DecoderInitDone(PipelineStatus status);
+
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
+  AudioDecoderList 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_this_;

[ddorwin, 2012/12/14 05:17:01]

shouldn't this be named ...factory_? The type is not obvious when reading the
.cc file. Is this common?

[xhwang, 2012/12/14 05:50:07]

I was following
http://code.google.com/searchframe#OAMlx_jo-ck/src/media/audio/audio_output_c...

Searched again. That's not the common use. Change it back. Thanks.

+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(AudioDecoderSelector);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_AUDIO_DECODER_SELECTOR_H_