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      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_
    121