Encrypted Media: Enforcing the CDM to decode audio into S16 integers.

webkit/media/crypto/ppapi/ffmpeg_cdm_audio_decoder.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 WEBKIT_MEDIA_CRYPTO_PPAPI_FFMPEG_CDM_AUDIO_DECODER_H_
 #define WEBKIT_MEDIA_CRYPTO_PPAPI_FFMPEG_CDM_AUDIO_DECODER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/time.h"
 #include "base/compiler_specific.h"
 #include "webkit/media/crypto/ppapi/cdm/content_decryption_module.h"
 
 struct AVCodecContext;
 struct AVFrame;
 
+namespace media {
+class AudioBus;
+class AudioTimestampHelper;
+}
+
 namespace webkit_media {
 
+// TODO(xhwang): This class is partially cloned from media::FFmpegAudioDecoder.
+// When media::FFmpegAudioDecoder is updated, it's a pain to keep this class
+// in sync with media::FFmpegAudioDecoder. We need a long term sustainable
+// solution for this. See http://crbug.com/169203
 class FFmpegCdmAudioDecoder {
  public:
   explicit FFmpegCdmAudioDecoder(cdm::Allocator* allocator);
   ~FFmpegCdmAudioDecoder();
   bool Initialize(const cdm::AudioDecoderConfig& config);
   void Deinitialize();
   void Reset();
 
   // Returns true when |config| is a valid audio decoder configuration.
   static bool IsValidConfig(const cdm::AudioDecoderConfig& config);
 
   // Decodes |compressed_buffer|. Returns |cdm::kSuccess| after storing
   // output in |decoded_frames| when output is available. Returns
   // |cdm::kNeedMoreData| when |compressed_frame| does not produce output.
   // Returns |cdm::kDecodeError| when decoding fails.
   cdm::Status DecodeBuffer(const uint8_t* compressed_buffer,
                            int32_t compressed_buffer_size,
                            int64_t timestamp,
                            cdm::AudioFrames* decoded_frames);
 
  private:
-  void ResetAudioTimingData();
+  void ResetTimestampState();
   void ReleaseFFmpegResources();
 
   base::TimeDelta GetNextOutputTimestamp() const;
 
   void SerializeInt64(int64_t value);
 
   bool is_initialized_;
 
   cdm::Allocator* const allocator_;
 
   // FFmpeg structures owned by this object.
   AVCodecContext* codec_context_;
   AVFrame* av_frame_;
 
   // Audio format.
   int bits_per_channel_;
   int samples_per_second_;
 
   // Used for computing output timestamps.
+  scoped_ptr<media::AudioTimestampHelper> output_timestamp_helper_;
   int bytes_per_frame_;
-  base::TimeDelta output_timestamp_base_;
-  int64_t total_frames_decoded_;
   base::TimeDelta last_input_timestamp_;
 
+  // We may need to convert the audio data coming out of FFmpeg from planar
+  // float to integer.
+  scoped_ptr<media::AudioBus> converter_bus_;
+
   // Number of output sample bytes to drop before generating output buffers.
   // This is required for handling negative timestamps when decoding Vorbis
   // audio, for example.
   int output_bytes_to_drop_;
 
   typedef std::vector<uint8_t> SerializedAudioFrames;
   SerializedAudioFrames serialized_audio_frames_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegCdmAudioDecoder);
 };
 
 }  // namespace webkit_media
 
 #endif  // WEBKIT_MEDIA_CRYPTO_PPAPI_FFMPEG_CDM_AUDIO_DECODER_H_