media/filters/decrypting_video_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_VIDEO_DECODER_H_
   6 #define MEDIA_FILTERS_DECRYPTING_VIDEO_DECODER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/weak_ptr.h"
  10 #include "media/base/decryptor.h"
  11 #include "media/base/video_decoder.h"
  12 #include "media/base/video_decoder_config.h"
  13
  14 namespace base {
  15 class SingleThreadTaskRunner;
  16 }
  17
  18 namespace media {
  19
  20 class DecoderBuffer;
  21 class Decryptor;
  22
  23 // Decryptor-based VideoDecoder implementation that can decrypt and decode
  24 // encrypted video buffers and return decrypted and decompressed video frames.
  25 // All public APIs and callbacks are trampolined to the |task_runner_| so
  26 // that no locks are required for thread safety.
  27 class MEDIA_EXPORT DecryptingVideoDecoder : public VideoDecoder {
  28  public:
  29   DecryptingVideoDecoder(
  30       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
  31       const SetDecryptorReadyCB& set_decryptor_ready_cb);
  32   virtual ~DecryptingVideoDecoder();
  33
  34   // VideoDecoder implementation.
  35   virtual std::string GetDisplayName() const OVERRIDE;
  36   virtual void Initialize(const VideoDecoderConfig& config,
  37                           bool low_delay,
  38                           const PipelineStatusCB& status_cb,
  39                           const OutputCB& output_cb) OVERRIDE;
  40   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
  41                       const DecodeCB& decode_cb) OVERRIDE;
  42   virtual void Reset(const base::Closure& closure) OVERRIDE;
  43
  44  private:
  45   // For a detailed state diagram please see this link: http://goo.gl/8jAok
  46   // TODO(xhwang): Add a ASCII state diagram in this file after this class
  47   // stabilizes.
  48   enum State {
  49     kUninitialized = 0,
  50     kDecryptorRequested,
  51     kPendingDecoderInit,
  52     kIdle,
  53     kPendingDecode,
  54     kWaitingForKey,
  55     kDecodeFinished,
  56     kError
  57   };
  58
  59   // Callback for DecryptorHost::RequestDecryptor(). |decryptor_attached_cb| is
  60   // called when the decryptor has been completely attached to the pipeline.
  61   void SetDecryptor(Decryptor* decryptor,
  62                     const DecryptorAttachedCB& decryptor_attached_cb);
  63
  64   // Callback for Decryptor::InitializeVideoDecoder() during initialization.
  65   void FinishInitialization(bool success);
  66
  67   void DecodePendingBuffer();
  68
  69   // Callback for Decryptor::DecryptAndDecodeVideo().
  70   void DeliverFrame(int buffer_size,
  71                     Decryptor::Status status,
  72                     const scoped_refptr<VideoFrame>& frame);
  73
  74   // Callback for the |decryptor_| to notify this object that a new key has been
  75   // added.
  76   void OnKeyAdded();
  77
  78   // Reset decoder and call |reset_cb_|.
  79   void DoReset();
  80
  81   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  82
  83   State state_;
  84
  85   PipelineStatusCB init_cb_;
  86   OutputCB output_cb_;
  87   DecodeCB decode_cb_;
  88   base::Closure reset_cb_;
  89
  90   VideoDecoderConfig config_;
  91
  92   // Callback to request/cancel decryptor creation notification.
  93   SetDecryptorReadyCB set_decryptor_ready_cb_;
  94
  95   Decryptor* decryptor_;
  96
  97   // The buffer that needs decrypting/decoding.
  98   scoped_refptr<media::DecoderBuffer> pending_buffer_to_decode_;
  99
 100   // Indicates the situation where new key is added during pending decode
 101   // (in other words, this variable can only be set in state kPendingDecode).
 102   // If this variable is true and kNoKey is returned then we need to try
 103   // decrypting/decoding again in case the newly added key is the correct
 104   // decryption key.
 105   bool key_added_while_decode_pending_;
 106
 107   // A unique ID to trace Decryptor::DecryptAndDecodeVideo() call and the
 108   // matching DecryptCB call (in DoDeliverFrame()).
 109   uint32 trace_id_;
 110
 111   // NOTE: Weak pointers must be invalidated before all other member variables.
 112   base::WeakPtrFactory<DecryptingVideoDecoder> weak_factory_;
 113   base::WeakPtr<DecryptingVideoDecoder> weak_this_;
 114
 115   DISALLOW_COPY_AND_ASSIGN(DecryptingVideoDecoder);
 116 };
 117
 118 }  // namespace media
 119
 120 #endif  // MEDIA_FILTERS_DECRYPTING_VIDEO_DECODER_H_