text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef MEDIA_FILTERS_DECRYPTING_DEMUXER_STREAM_H_
  #define MEDIA_FILTERS_DECRYPTING_DEMUXER_STREAM_H_
  
  #include "base/callback.h"
  #include "base/macros.h"
  #include "base/memory/ref_counted.h"
  #include "base/memory/weak_ptr.h"
  #include "media/base/audio_decoder_config.h"
  #include "media/base/cdm_context.h"
  #include "media/base/decryptor.h"
  #include "media/base/demuxer_stream.h"
  #include "media/base/pipeline_status.h"
  #include "media/base/video_decoder_config.h"
  
  namespace base {
  class SingleThreadTaskRunner;
  }
  
  namespace media {
  
  class DecoderBuffer;
  class MediaLog;
  
  // Decryptor-based DemuxerStream implementation that converts a potentially
  // encrypted demuxer stream to a clear demuxer stream.
  // All public APIs and callbacks are trampolined to the |task_runner_| so
  // that no locks are required for thread safety.
  class MEDIA_EXPORT DecryptingDemuxerStream : public DemuxerStream {
   public:
    DecryptingDemuxerStream(
        const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
        MediaLog* media_log,
        const base::Closure& waiting_for_decryption_key_cb);
  
    // Cancels all pending operations immediately and fires all pending callbacks.
    ~DecryptingDemuxerStream() override;
  
    // |steram| must be encrypted and |cdm_context| must be non-null.
    void Initialize(DemuxerStream* stream,
                    CdmContext* cdm_context,
                    const PipelineStatusCB& status_cb);
  
    // Cancels all pending operations and fires all pending callbacks. If in
    // kPendingDemuxerRead or kPendingDecrypt state, waits for the pending
    // operation to finish before satisfying |closure|. Sets the state to
    // kUninitialized if |this| hasn't been initialized, or to kIdle otherwise.
    void Reset(const base::Closure& closure);
  
    // Returns the name of this class for logging purpose.
    std::string GetDisplayName() const;
  
    // DemuxerStream implementation.
    void Read(const ReadCB& read_cb) override;
    AudioDecoderConfig audio_decoder_config() override;
    VideoDecoderConfig video_decoder_config() override;
    Type type() const override;
    Liveness liveness() const override;
    void EnableBitstreamConverter() override;
    bool SupportsConfigChanges() override;
  
   private:
    // For a detailed state diagram please see this link: http://goo.gl/8jAok
    // TODO(xhwang): Add a ASCII state diagram in this file after this class
    // stabilizes.
    // TODO(xhwang): Update this diagram for DecryptingDemuxerStream.
    enum State {
      kUninitialized = 0,
      kIdle,
      kPendingDemuxerRead,
      kPendingDecrypt,
      kWaitingForKey
    };
  
    // Callback for DemuxerStream::Read().
    void DecryptBuffer(DemuxerStream::Status status,
                       scoped_refptr<DecoderBuffer> buffer);
  
    void DecryptPendingBuffer();
  
    // Callback for Decryptor::Decrypt().
    void DeliverBuffer(Decryptor::Status status,
                       scoped_refptr<DecoderBuffer> decrypted_buffer);
  
    // Callback for the |decryptor_| to notify this object that a new key has been
    // added.
    void OnKeyAdded();
  
    // Resets decoder and calls |reset_cb_|.
    void DoReset();
  
    // Returns Decryptor::StreamType converted from |stream_type_|.
    Decryptor::StreamType GetDecryptorStreamType() const;
  
    // Creates and initializes either |audio_config_| or |video_config_| based on
    // |demuxer_stream_|.
    void InitializeDecoderConfig();
  
    scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  
    MediaLog* media_log_;
  
    State state_;
  
    PipelineStatusCB init_cb_;
    ReadCB read_cb_;
    base::Closure reset_cb_;
    base::Closure waiting_for_decryption_key_cb_;
  
    // Pointer to the input demuxer stream that will feed us encrypted buffers.
    DemuxerStream* demuxer_stream_;
  
    AudioDecoderConfig audio_config_;
    VideoDecoderConfig video_config_;
  
    Decryptor* decryptor_;
  
    // The buffer returned by the demuxer that needs to be decrypted.
    scoped_refptr<media::DecoderBuffer> pending_buffer_to_decrypt_;
  
    // Indicates the situation where new key is added during pending decryption
    // (in other words, this variable can only be set in state kPendingDecrypt).
    // If this variable is true and kNoKey is returned then we need to try
    // decrypting again in case the newly added key is the correct decryption key.
    bool key_added_while_decrypt_pending_;
  
    base::WeakPtr<DecryptingDemuxerStream> weak_this_;
    base::WeakPtrFactory<DecryptingDemuxerStream> weak_factory_;
  
    DISALLOW_COPY_AND_ASSIGN(DecryptingDemuxerStream);
  };
  
  }  // namespace media
  
  #endif  // MEDIA_FILTERS_DECRYPTING_DEMUXER_STREAM_H_
  