Motown: ffmpeg implementations of framework 'parts'

services/media/framework_ffmpeg/ffmpeg_decoder_base.h

+// Copyright 2016 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 SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_DECODER_BASE_H_
+#define SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_DECODER_BASE_H_
+
+#include "services/media/framework_ffmpeg/ffmpeg_decoder.h"
+extern "C" {
+#include "third_party/ffmpeg/libavcodec/avcodec.h"
+}
+
+namespace mojo {
+namespace media {
+
+// Abstract base class for ffmpeg-based decoders.
+class FfmpegDecoderBase : public FfmpegDecoder {

[johngro, 2016/03/01 01:31:38]

This could just derive from Decoder instead of FfmpegDecoder, since
FfmpegDecoder is basically just acting as a namespace for the Create method.

[dalesat, 2016/03/01 20:43:01]

Done.

+ public:
+  FfmpegDecoderBase(AVCodecContext *av_codec_context);
+
+  ~FfmpegDecoderBase() override;
+
+  // Decoder implementation.
+  Result Init(const StreamType& stream_type) override;
+
+  std::unique_ptr<StreamType> output_stream_type() override;
+
+  // Transform implementation.
+  void Flush() override;
+
+  bool TransformPacket(
+      const PacketPtr& input,
+      bool new_input,
+      PayloadAllocator* allocator,
+      PacketPtr* output) override;
+
+ protected:
+  struct AVCodecContextDeleter {
+    inline void operator()(AVCodecContext* ptr) const {
+      avcodec_free_context(&ptr);
+    }
+  };
+
+  struct AVFrameDeleter {
+    inline void operator()(AVFrame* ptr) const {
+      av_frame_free(&ptr);
+    }
+  };
+
+  // Decodes from av_packet_ into av_frame_. The result indicates how many
+  // bytes were consumed from av_packet_. *frame_decoded_out indicates whether
+  // av_frame_ contains a complete frame.
+  virtual int Decode(PayloadAllocator* allocator, bool* frame_decoded_out) = 0;
+
+  // Creates a Packet from av_frame_.
+  virtual PacketPtr CreateOutputPacket(PayloadAllocator* allocator) = 0;
+
+  std::unique_ptr<AVCodecContext, AVCodecContextDeleter> av_codec_context_;
+
+  // Ffmpeg's representation of the input packet.
+  AVPacket av_packet_;
+
+  // Ffmpeg's representation of the output packet.
+  std::unique_ptr<AVFrame, AVFrameDeleter> av_frame_;
+
+  // Presentation time + duration from the previous packet.
+  int64_t next_presentation_time_;
+
+ private:
+  // Prepares to process a new input packet.
+  void PrepareInputPacket(const PacketPtr& input);
+
+  // Finishes up after processing of an input packet has completed, possibly
+  // producing a zero-size end-of-stream packet. Returns true to indicate that
+  // a new input packet is required.
+  bool UnprepareInputPacket(const PacketPtr& input, PacketPtr* output);
+
+  // Creates an output packet from av_frame_.
+  PacketPtr PacketFromAvFrame(PayloadAllocator* allocator);
+};
+
+}  // namespace media
+}  // namespace mojo
+
+#endif // SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_DECODER_BASE_H_