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 MessageLoopProxy;
  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 |message_loop_| 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::MessageLoopProxy>& message_loop,
  42       const SetDecryptorReadyCB& set_decryptor_ready_cb);
  43   virtual ~DecryptingAudioDecoder();
  44
  45   // AudioDecoder implementation.
  46   virtual void Initialize(DemuxerStream* stream,
  47                           const PipelineStatusCB& status_cb,
  48                           const StatisticsCB& statistics_cb) OVERRIDE;
  49   virtual void Read(const ReadCB& read_cb) OVERRIDE;
  50   virtual void Reset(const base::Closure& closure) OVERRIDE;
  51   virtual int bits_per_channel() OVERRIDE;
  52   virtual ChannelLayout channel_layout() OVERRIDE;
  53   virtual int samples_per_second() OVERRIDE;
  54
  55  private:
  56   // For a detailed state diagram please see this link: http://goo.gl/8jAok
  57   // TODO(xhwang): Add a ASCII state diagram in this file after this class
  58   // stabilizes.
  59   // TODO(xhwang): Update this diagram for DecryptingAudioDecoder.
  60   enum State {
  61     kUninitialized = 0,
  62     kDecryptorRequested,
  63     kPendingDecoderInit,
  64     kIdle,
  65     kPendingConfigChange,
  66     kPendingDemuxerRead,
  67     kPendingDecode,
  68     kWaitingForKey,
  69     kDecodeFinished,
  70   };
  71
  72   // Callback for DecryptorHost::RequestDecryptor().
  73   void SetDecryptor(Decryptor* decryptor);
  74
  75   // Callback for Decryptor::InitializeAudioDecoder() during initialization.
  76   void FinishInitialization(bool success);
  77
  78   // Callback for Decryptor::InitializeAudioDecoder() during config change.
  79   void FinishConfigChange(bool success);
  80
  81   // Reads from the demuxer stream with corresponding callback method.
  82   void ReadFromDemuxerStream();
  83   void DecryptAndDecodeBuffer(DemuxerStream::Status status,
  84                               const scoped_refptr<DecoderBuffer>& buffer);
  85
  86   void DecodePendingBuffer();
  87
  88   // Callback for Decryptor::DecryptAndDecodeAudio().
  89   void DeliverFrame(int buffer_size,
  90                     Decryptor::Status status,
  91                     const Decryptor::AudioBuffers& frames);
  92
  93   // Callback for the |decryptor_| to notify this object that a new key has been
  94   // added.
  95   void OnKeyAdded();
  96
  97   // Resets decoder and calls |reset_cb_|.
  98   void DoReset();
  99
 100   // Updates audio configs from |demuxer_stream_| and resets
 101   // |output_timestamp_base_| and |total_samples_decoded_|.
 102   void UpdateDecoderConfig();
 103
 104   // Sets timestamp and duration for |queued_audio_frames_| to make sure the
 105   // renderer always receives continuous frames without gaps and overlaps.
 106   void EnqueueFrames(const Decryptor::AudioBuffers& frames);
 107
 108   scoped_refptr<base::MessageLoopProxy> message_loop_;
 109   base::WeakPtrFactory<DecryptingAudioDecoder> weak_factory_;
 110   base::WeakPtr<DecryptingAudioDecoder> weak_this_;
 111
 112   State state_;
 113
 114   PipelineStatusCB init_cb_;
 115   StatisticsCB statistics_cb_;
 116   ReadCB read_cb_;
 117   base::Closure reset_cb_;
 118
 119   // Pointer to the demuxer stream that will feed us compressed buffers.
 120   DemuxerStream* demuxer_stream_;
 121
 122   // Callback to request/cancel decryptor creation notification.
 123   SetDecryptorReadyCB set_decryptor_ready_cb_;
 124
 125   Decryptor* decryptor_;
 126
 127   // The buffer returned by the demuxer that needs decrypting/decoding.
 128   scoped_refptr<media::DecoderBuffer> pending_buffer_to_decode_;
 129
 130   // Indicates the situation where new key is added during pending decode
 131   // (in other words, this variable can only be set in state kPendingDecode).
 132   // If this variable is true and kNoKey is returned then we need to try
 133   // decrypting/decoding again in case the newly added key is the correct
 134   // decryption key.
 135   bool key_added_while_decode_pending_;
 136
 137   Decryptor::AudioBuffers queued_audio_frames_;
 138
 139   // Decoded audio format.
 140   int bits_per_channel_;
 141   ChannelLayout channel_layout_;
 142   int samples_per_second_;
 143
 144   scoped_ptr<AudioTimestampHelper> timestamp_helper_;
 145
 146   DISALLOW_COPY_AND_ASSIGN(DecryptingAudioDecoder);
 147 };
 148
 149 }  // namespace media
 150
 151 #endif  // MEDIA_FILTERS_DECRYPTING_AUDIO_DECODER_H_