Motown: Ffmpeg video decoder

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/parts/decoder.h"
 #include "services/media/framework_ffmpeg/av_codec_context.h"
 #include "services/media/framework_ffmpeg/av_frame.h"
@@ skipping 17 matching lines @@
 
   // Transform implementation.
   void Flush() override;
 
   bool TransformPacket(const PacketPtr& input,
                        bool new_input,
                        PayloadAllocator* allocator,
                        PacketPtr* output) override;
 
  protected:
+  // Used to control deallocation of buffers.
+  class AvBufferContext {
+   public:
+    AvBufferContext(size_t size, PayloadAllocator* allocator)
+        : size_(size), allocator_(allocator) {
+      DCHECK(allocator_);
+      if (size_ == 0) {
+        buffer_ = nullptr;
+      } else {
+        buffer_ =
+            static_cast<uint8_t*>(allocator_->AllocatePayloadBuffer(size_));
+      }
+    }
+
+    ~AvBufferContext() {
+      if (allocator_ == nullptr) {
+        // Previously released.
+        return;
+      }
+
+      if (size_ != 0) {
+        DCHECK(buffer_ != nullptr);
+        allocator_->ReleasePayloadBuffer(size_, buffer_);
+        return;
+      }
+
+      DCHECK(buffer_ == nullptr);
+    }
+
+    uint8_t* buffer() { return buffer_; }
+
+    size_t size() { return size_; }
+
+    // Releases ownership of the buffer.
+    uint8_t* Release() {
+      DCHECK(allocator_) << "AvBufferContext released twice";
+      uint8_t* result = buffer_;
+      buffer_ = nullptr;
+      size_ = 0;
+      allocator_ = nullptr;
+      return result;
+    }
+
+   private:
+    uint8_t* buffer_;
+    size_t size_;
+    PayloadAllocator* allocator_;
+  };
+
   // Decodes from av_packet into av_frame_ptr. The result indicates how many
   // bytes were consumed from av_packet_. *frame_decoded_out indicates whether
   // av_frame_ptr contains a complete frame.
   virtual int Decode(const AVPacket& av_packet,
                      const ffmpeg::AvFramePtr& av_frame_ptr,
                      PayloadAllocator* allocator,
                      bool* frame_decoded_out) = 0;
 
   // Creates a Packet from av_frame.
   virtual PacketPtr CreateOutputPacket(const AVFrame& av_frame,
@@ skipping 16 matching lines @@
 
   AvCodecContextPtr av_codec_context_;
   AVPacket av_packet_;
   ffmpeg::AvFramePtr av_frame_ptr_;
 };
 
 }  // namespace media
 }  // namespace mojo
 
 #endif  // SERVICES_MEDIA_FRAMEWORK_FFMPEG_FFMPEG_DECODER_BASE_H_