media/filters/decrypting_audio_decoder.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_FILTERS_DECRYPTING_AUDIO_DECODER_H_
   6 #define MEDIA_FILTERS_DECRYPTING_AUDIO_DECODER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "base/time/time.h"
  13 #include "media/base/audio_decoder.h"
  14 #include "media/base/decryptor.h"
  15 #include "media/base/demuxer_stream.h"
  16
  17 namespace base {
  18 class SingleThreadTaskRunner;
  19 }
  20
  21 namespace media {
  22
  23 class AudioTimestampHelper;
  24 class DecoderBuffer;
  25 class Decryptor;
  26
  27 // Decryptor-based AudioDecoder implementation that can decrypt and decode
  28 // encrypted audio buffers and return decrypted and decompressed audio frames.
  29 // All public APIs and callbacks are trampolined to the |task_runner_| so
  30 // that no locks are required for thread safety.
  31 class MEDIA_EXPORT DecryptingAudioDecoder : public AudioDecoder {
  32  public:
  33   // We do not currently have a way to let the Decryptor choose the output
  34   // audio sample format and notify us of its choice. Therefore, we require all
  35   // Decryptor implementations to decode audio into a fixed integer sample
  36   // format designated by kSupportedBitsPerChannel.
  37   // TODO(xhwang): Remove this restriction after http://crbug.com/169105 fixed.
  38   static const int kSupportedBitsPerChannel;
  39
  40   DecryptingAudioDecoder(
  41       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
  42       const SetDecryptorReadyCB& set_decryptor_ready_cb);
  43   virtual ~DecryptingAudioDecoder();
  44
  45   // AudioDecoder implementation.
  46   virtual void Initialize(const AudioDecoderConfig& config,
  47                           const PipelineStatusCB& status_cb,
  48                           const OutputCB& output_cb) OVERRIDE;
  49   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
  50                       const DecodeCB& decode_cb) OVERRIDE;
  51   virtual void Reset(const base::Closure& closure) OVERRIDE;
  52
  53  private:
  54   // For a detailed state diagram please see this link: http://goo.gl/8jAok
  55   // TODO(xhwang): Add a ASCII state diagram in this file after this class
  56   // stabilizes.
  57   // TODO(xhwang): Update this diagram for DecryptingAudioDecoder.
  58   enum State {
  59     kUninitialized = 0,
  60     kDecryptorRequested,
  61     kPendingDecoderInit,
  62     kIdle,
  63     kPendingDecode,
  64     kWaitingForKey,
  65     kDecodeFinished,
  66     kError
  67   };
  68
  69   // Callback for DecryptorHost::RequestDecryptor().
  70   void SetDecryptor(Decryptor* decryptor);
  71
  72   // Initializes the audio decoder on the |decryptor_| with |config_|.
  73   void InitializeDecoder();
  74
  75   // Callback for Decryptor::InitializeAudioDecoder() during initialization.
  76   void FinishInitialization(bool success);
  77
  78   void DecodePendingBuffer();
  79
  80   // Callback for Decryptor::DecryptAndDecodeAudio().
  81   void DeliverFrame(int buffer_size,
  82                     Decryptor::Status status,
  83                     const Decryptor::AudioBuffers& frames);
  84
  85   // Callback for the |decryptor_| to notify this object that a new key has been
  86   // added.
  87   void OnKeyAdded();
  88
  89   // Resets decoder and calls |reset_cb_|.
  90   void DoReset();
  91
  92   // Sets timestamps for |frames| and then passes them to |output_cb_|.
  93   void ProcessDecodedFrames(const Decryptor::AudioBuffers& frames);
  94
  95   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  96
  97   State state_;
  98
  99   PipelineStatusCB init_cb_;
 100   OutputCB output_cb_;
 101   DecodeCB decode_cb_;
 102   base::Closure reset_cb_;
 103
 104   // The current decoder configuration.
 105   AudioDecoderConfig config_;
 106
 107   // Callback to request/cancel decryptor creation notification.
 108   SetDecryptorReadyCB set_decryptor_ready_cb_;
 109
 110   Decryptor* decryptor_;
 111
 112   // The buffer that needs decrypting/decoding.
 113   scoped_refptr<media::DecoderBuffer> pending_buffer_to_decode_;
 114
 115   // Indicates the situation where new key is added during pending decode
 116   // (in other words, this variable can only be set in state kPendingDecode).
 117   // If this variable is true and kNoKey is returned then we need to try
 118   // decrypting/decoding again in case the newly added key is the correct
 119   // decryption key.
 120   bool key_added_while_decode_pending_;
 121
 122   scoped_ptr<AudioTimestampHelper> timestamp_helper_;
 123
 124   // NOTE: Weak pointers must be invalidated before all other member variables.
 125   base::WeakPtrFactory<DecryptingAudioDecoder> weak_factory_;
 126   base::WeakPtr<DecryptingAudioDecoder> weak_this_;
 127
 128   DISALLOW_COPY_AND_ASSIGN(DecryptingAudioDecoder);
 129 };
 130
 131 }  // namespace media
 132
 133 #endif  // MEDIA_FILTERS_DECRYPTING_AUDIO_DECODER_H_