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   ~DecryptingAudioDecoder() override;
  44
  45   // AudioDecoder implementation.
  46   std::string GetDisplayName() const override;
  47   void Initialize(const AudioDecoderConfig& config,
  48                   const PipelineStatusCB& status_cb,
  49                   const OutputCB& output_cb) override;
  50   void Decode(const scoped_refptr<DecoderBuffer>& buffer,
  51               const DecodeCB& decode_cb) override;
  52   void Reset(const base::Closure& closure) override;
  53
  54  private:
  55   // For a detailed state diagram please see this link: http://goo.gl/8jAok
  56   // TODO(xhwang): Add a ASCII state diagram in this file after this class
  57   // stabilizes.
  58   // TODO(xhwang): Update this diagram for DecryptingAudioDecoder.
  59   enum State {
  60     kUninitialized = 0,
  61     kDecryptorRequested,
  62     kPendingDecoderInit,
  63     kIdle,
  64     kPendingDecode,
  65     kWaitingForKey,
  66     kDecodeFinished,
  67     kError
  68   };
  69
  70   // Callback for DecryptorHost::RequestDecryptor(). |decryptor_attached_cb| is
  71   // called when the decryptor has been completely attached to the pipeline.
  72   void SetDecryptor(Decryptor* decryptor,
  73                     const DecryptorAttachedCB& decryptor_attached_cb);
  74
  75   // Initializes the audio decoder on the |decryptor_| with |config_|.
  76   void InitializeDecoder();
  77
  78   // Callback for Decryptor::InitializeAudioDecoder() during initialization.
  79   void FinishInitialization(bool success);
  80
  81   void DecodePendingBuffer();
  82
  83   // Callback for Decryptor::DecryptAndDecodeAudio().
  84   void DeliverFrame(int buffer_size,
  85                     Decryptor::Status status,
  86                     const Decryptor::AudioBuffers& frames);
  87
  88   // Callback for the |decryptor_| to notify this object that a new key has been
  89   // added.
  90   void OnKeyAdded();
  91
  92   // Resets decoder and calls |reset_cb_|.
  93   void DoReset();
  94
  95   // Sets timestamps for |frames| and then passes them to |output_cb_|.
  96   void ProcessDecodedFrames(const Decryptor::AudioBuffers& frames);
  97
  98   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  99
 100   State state_;
 101
 102   PipelineStatusCB init_cb_;
 103   OutputCB output_cb_;
 104   DecodeCB decode_cb_;
 105   base::Closure reset_cb_;
 106
 107   // The current decoder configuration.
 108   AudioDecoderConfig config_;
 109
 110   // Callback to request/cancel decryptor creation notification.
 111   SetDecryptorReadyCB set_decryptor_ready_cb_;
 112
 113   Decryptor* decryptor_;
 114
 115   // The buffer that needs decrypting/decoding.
 116   scoped_refptr<media::DecoderBuffer> pending_buffer_to_decode_;
 117
 118   // Indicates the situation where new key is added during pending decode
 119   // (in other words, this variable can only be set in state kPendingDecode).
 120   // If this variable is true and kNoKey is returned then we need to try
 121   // decrypting/decoding again in case the newly added key is the correct
 122   // decryption key.
 123   bool key_added_while_decode_pending_;
 124
 125   scoped_ptr<AudioTimestampHelper> timestamp_helper_;
 126
 127   // NOTE: Weak pointers must be invalidated before all other member variables.
 128   base::WeakPtrFactory<DecryptingAudioDecoder> weak_factory_;
 129   base::WeakPtr<DecryptingAudioDecoder> weak_this_;
 130
 131   DISALLOW_COPY_AND_ASSIGN(DecryptingAudioDecoder);
 132 };
 133
 134 }  // namespace media
 135
 136 #endif  // MEDIA_FILTERS_DECRYPTING_AUDIO_DECODER_H_