Add video decoding methods in Decryptor and add DecryptingVideoDecoder.

media/base/decryptor.h

 // 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_BASE_DECRYPTOR_H_
 #define MEDIA_BASE_DECRYPTOR_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 class DecoderBuffer;
+class VideoDecoderConfig;
+class VideoFrame;
 
-// Performs key operations and decrypts encrypted buffer.
-// All public methods other than Decrypt() will be called on the renderer
-// thread. Therefore, these calls should be fast and nonblocking, with key
-// events fired asynchronously. Decrypt() will be called on the (video/audio)
-// decoder thread.
+// Performs key operations and decrypts (and decodes) encrypted buffer.
+//
+// Key operations (GenerateKeyRequest(), AddKey() and CancelKeyRequest())
+// are called on the renderer thread. Therefore, these calls should be fast
+// and nonblocking; key events should be fired asynchronously.
+// All other methods are called on the (video/audio) decoder thread.
+// Decryptor implementations must be thread safe when methods are called
+// following the above model.
+// Depending on the implementation callbacks may be fired synchronously or
+// asynchronously.
 class MEDIA_EXPORT Decryptor {
  public:
   enum KeyError {
     kUnknownError = 1,
     kClientError,
     kServiceError,
     kOutputError,
     kHardwareChangeError,
     kDomainError
   };
 
   enum Status {
     kSuccess,  // Decryption successfully completed. Decrypted buffer ready.
     kNoKey,  // No key is available to decrypt.
+    kNeedMoreData,  // Decoder needs more data to produce a frame.
     kError  // Key is available but an error occurred during decryption.
   };
 
-  Decryptor() {}
-  virtual ~Decryptor() {}
+  Decryptor();
+  virtual ~Decryptor();
 
   // Generates a key request for the |key_system| with |init_data| provided.
   // Returns true if generating key request succeeded, false otherwise.
   // Note: AddKey() and CancelKeyRequest() should only be called after
   // GenerateKeyRequest() returns true.
   virtual bool GenerateKeyRequest(const std::string& key_system,
                                   const uint8* init_data,
                                   int init_data_length) = 0;
 
   // Adds a |key| to the |key_system|. The |key| is not limited to a decryption
   // key. It can be any data that the key system accepts, such as a license.
   // If multiple calls of this function set different keys for the same
   // key ID, the older key will be replaced by the newer key.
   virtual void AddKey(const std::string& key_system,
                       const uint8* key,
                       int key_length,
                       const uint8* init_data,
                       int init_data_length,
                       const std::string& session_id) = 0;
 
   // Cancels the key request specified by |session_id|.
   virtual void CancelKeyRequest(const std::string& key_system,
                                 const std::string& session_id) = 0;
 
+  // Indicates completion of a decryption operation.
+  //
+  // First parameter: The status of the decryption operation.
+  // - Set to kSuccess if the encrypted buffer is successfully decrypted and
+  //   the decrypted buffer is ready to be read.
+  // - Set to kNoKey if no decryption key is available to decrypt the encrypted
+  //   buffer. In this case the decrypted buffer must be NULL.
+  // - Set to kError if unexpected error has occurred. In this case the
+  //   decrypted buffer must be NULL.
+  // - This parameter should not be set to kNeedMoreData.
+  // Second parameter: The decrypted buffer.
+  typedef base::Callback<void(Status,
+                              const scoped_refptr<DecoderBuffer>&)> DecryptCB;
+
   // Decrypts the |encrypted| buffer. The decrypt status and decrypted buffer
   // are returned via the provided callback |decrypt_cb|. The |encrypted| buffer
   // must not be NULL.
   // Decrypt() should not be called until any previous DecryptCB has completed.
   // Thus, only one DecryptCB may be pending at a time.
-  // Note that the callback maybe called synchronously or asynchronously.
-  //
-  // If the returned status is kSuccess, the |encrypted| buffer is successfully
-  // decrypted and the decrypted buffer is ready to be read.
-  // If the returned status is kNoKey, no decryption key is available to decrypt
-  // |encrypted| buffer. In this case the decrypted buffer must be NULL.
-  // If the returned status is kError, unexpected error has occurred. In this
-  // case the decrypted buffer must be NULL.
-  typedef base::Callback<void(Status,
-                              const scoped_refptr<DecoderBuffer>&)> DecryptCB;
   virtual void Decrypt(const scoped_refptr<DecoderBuffer>& encrypted,
                        const DecryptCB& decrypt_cb) = 0;
 
   // Cancels the scheduled decryption operation and fires the pending DecryptCB
   // immediately with kSuccess and NULL.
   // Decrypt() should not be called again before the pending DecryptCB is fired.
   virtual void CancelDecrypt() = 0;
 
+  // Indicates completion of decoder initialization.
+  //
+  // First Parameter: Indicates initialization success.
+  // - Set to true if initialization was successful. False if an error occurred.
+  typedef base::Callback<void(bool)> DecoderInitCB;
+
+  // Initializes a video decoder with the given |config|, executing the
+  // |init_cb| upon completion.
+  // Note: DecryptAndDecodeVideo(), ResetVideoDecoder() and StopVideoDecoder()
+  // can only be called after InitializeVideoDecoder() succeeded.
+  virtual void InitializeVideoDecoder(const VideoDecoderConfig& config,
+                                      const DecoderInitCB& init_cb) = 0;
+
+  // Indicates completion of video decrypting and decoding operation.
+  //
+  // First parameter: The status of the decrypting and decoding operation.
+  // - Set to kSuccess if the encrypted buffer is successfully decrypted and
+  //   decoded. In this case, the decoded video frame can be:
+  //   1) NULL, which means the operation has been aborted.
+  //   2) End-of-stream (EOS) frame, which means that the decoder has hit EOS,
+  //      flushed all internal buffers and cannot produce more video frames.
+  //   3) Decrypted and decoded video frame.
+  // - Set to kNoKey if no decryption key is available to decrypt the encrypted
+  //   buffer. In this case the decoded video frame must be NULL.
+  // - Set to kNeedMoreData if more data is needed to produce a video frame. In
+  //   this case the decoded video frame must be NULL.
+  // - Set to kError if unexpected error has occurred. In this case the
+  //   decoded video frame must be NULL.
+  // Second parameter: The decoded video frame.
+  typedef base::Callback<void(Status,
+                              const scoped_refptr<VideoFrame>&)> VideoDecodeCB;
+
+  // Decrypts and decodes the |encrypted| buffer. The status and the decrypted
+  // buffer are returned via the provided callback |video_decode_cb|.
+  // The |encrypted| buffer must not be NULL.
+  // At end-of-stream, this method should be called repeatedly with
+  // end-of-stream DecoderBuffer until no video frame can be produced.
+  virtual void DecryptAndDecodeVideo(
+      const scoped_refptr<DecoderBuffer>& encrypted,
+      const VideoDecodeCB& video_decode_cb) = 0;
+
+  // Cancels scheduled video decrypt-and-decode operations and fires any pending
+  // VideoDecodeCB immediately with kError and NULL frame.
+  virtual void CancelDecryptAndDecodeVideo() = 0;
+
+  // Stops decoder and sets it to an uninitialized state.
+  // The decoder can be reinitialized by calling InitializeVideoDecoder() after
+  // it is stopped.
+  virtual void StopVideoDecoder() = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(Decryptor);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_DECRYPTOR_H_