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(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 void Stop(const base::Closure& closure) OVERRIDE;
  52   virtual int bits_per_channel() OVERRIDE;
  53   virtual ChannelLayout channel_layout() OVERRIDE;
  54   virtual int samples_per_second() OVERRIDE;
  55
  56  private:
  57   // For a detailed state diagram please see this link: http://goo.gl/8jAok
  58   // TODO(xhwang): Add a ASCII state diagram in this file after this class
  59   // stabilizes.
  60   // TODO(xhwang): Update this diagram for DecryptingAudioDecoder.
  61   enum State {
  62     kUninitialized = 0,
  63     kDecryptorRequested,
  64     kPendingDecoderInit,
  65     kIdle,
  66     kPendingConfigChange,
  67     kPendingDemuxerRead,
  68     kPendingDecode,
  69     kWaitingForKey,
  70     kDecodeFinished,
  71     kStopped,
  72   };
  73
  74   // Callback for DecryptorHost::RequestDecryptor().
  75   void SetDecryptor(Decryptor* decryptor);
  76
  77   // Callback for Decryptor::InitializeAudioDecoder() during initialization.
  78   void FinishInitialization(bool success);
  79
  80   // Callback for Decryptor::InitializeAudioDecoder() during config change.
  81   void FinishConfigChange(bool success);
  82
  83   // Reads from the demuxer stream with corresponding callback method.
  84   void ReadFromDemuxerStream();
  85   void DecryptAndDecodeBuffer(DemuxerStream::Status status,
  86                               const scoped_refptr<DecoderBuffer>& buffer);
  87
  88   void DecodePendingBuffer();
  89
  90   // Callback for Decryptor::DecryptAndDecodeAudio().
  91   void DeliverFrame(int buffer_size,
  92                     Decryptor::Status status,
  93                     const Decryptor::AudioBuffers& frames);
  94
  95   // Callback for the |decryptor_| to notify this object that a new key has been
  96   // added.
  97   void OnKeyAdded();
  98
  99   // Resets decoder and calls |reset_cb_|.
 100   void DoReset();
 101
 102   // Updates audio configs from |demuxer_stream_| and resets
 103   // |output_timestamp_base_| and |total_samples_decoded_|.
 104   void UpdateDecoderConfig();
 105
 106   // Sets timestamp and duration for |queued_audio_frames_| to make sure the
 107   // renderer always receives continuous frames without gaps and overlaps.
 108   void EnqueueFrames(const Decryptor::AudioBuffers& frames);
 109
 110   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 111   base::WeakPtrFactory<DecryptingAudioDecoder> weak_factory_;
 112   base::WeakPtr<DecryptingAudioDecoder> weak_this_;
 113
 114   State state_;
 115
 116   PipelineStatusCB init_cb_;
 117   StatisticsCB statistics_cb_;
 118   ReadCB read_cb_;
 119   base::Closure reset_cb_;
 120   base::Closure stop_cb_;
 121
 122   // Pointer to the demuxer stream that will feed us compressed buffers.
 123   DemuxerStream* demuxer_stream_;
 124
 125   // Callback to request/cancel decryptor creation notification.
 126   SetDecryptorReadyCB set_decryptor_ready_cb_;
 127
 128   Decryptor* decryptor_;
 129
 130   // The buffer returned by the demuxer that needs decrypting/decoding.
 131   scoped_refptr<media::DecoderBuffer> pending_buffer_to_decode_;
 132
 133   // Indicates the situation where new key is added during pending decode
 134   // (in other words, this variable can only be set in state kPendingDecode).
 135   // If this variable is true and kNoKey is returned then we need to try
 136   // decrypting/decoding again in case the newly added key is the correct
 137   // decryption key.
 138   bool key_added_while_decode_pending_;
 139
 140   Decryptor::AudioBuffers queued_audio_frames_;
 141
 142   // Decoded audio format.
 143   int bits_per_channel_;
 144   ChannelLayout channel_layout_;
 145   int samples_per_second_;
 146
 147   scoped_ptr<AudioTimestampHelper> timestamp_helper_;
 148
 149   DISALLOW_COPY_AND_ASSIGN(DecryptingAudioDecoder);
 150 };
 151
 152 }  // namespace media
 153
 154 #endif  // MEDIA_FILTERS_DECRYPTING_AUDIO_DECODER_H_