1 files changed, 109 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h b/third_party/libwebrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h
new file mode 100644
index 0000000000..97d091cf4b
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+++ b/third_party/libwebrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h
@@ -0,0 +1,109 @@
+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ *
+ */
+
+#ifndef MODULES_VIDEO_CODING_CODECS_H264_H264_DECODER_IMPL_H_
+#define MODULES_VIDEO_CODING_CODECS_H264_H264_DECODER_IMPL_H_
+
+// Everything declared in this header is only required when WebRTC is
+// build with H264 support, please do not move anything out of the
+// #ifdef unless needed and tested.
+#ifdef WEBRTC_USE_H264
+
+#if defined(WEBRTC_WIN) && !defined(__clang__)
+#error "See: bugs.webrtc.org/9213#c13."
+#endif
+
+#include <memory>
+
+#include "modules/video_coding/codecs/h264/include/h264.h"
+
+// CAVEAT: According to ffmpeg docs for avcodec_send_packet, ffmpeg requires a
+// few extra padding bytes after the end of input. And in addition, docs for
+// AV_INPUT_BUFFER_PADDING_SIZE says "If the first 23 bits of the additional
+// bytes are not 0, then damaged MPEG bitstreams could cause overread and
+// segfault."
+//
+// WebRTC doesn't ensure any such padding, and REQUIRES ffmpeg to be compiled
+// with CONFIG_SAFE_BITSTREAM_READER, which is intended to eliminate
+// out-of-bounds reads. ffmpeg docs doesn't say explicitly what effects this
+// flag has on the h.264 decoder or avcodec_send_packet, though, so this is in
+// some way depending on undocumented behavior. If any problems turn up, we may
+// have to add an extra copy operation, to enforce padding before buffers are
+// passed to ffmpeg.
+
+extern "C" {
+#include "third_party/ffmpeg/libavcodec/avcodec.h"
+}  // extern "C"
+
+#include "common_video/h264/h264_bitstream_parser.h"
+#include "common_video/include/video_frame_buffer_pool.h"
+
+namespace webrtc {
+
+struct AVCodecContextDeleter {
+  void operator()(AVCodecContext* ptr) const { avcodec_free_context(&ptr); }
+};
+struct AVFrameDeleter {
+  void operator()(AVFrame* ptr) const { av_frame_free(&ptr); }
+};
+
+class H264DecoderImpl : public H264Decoder {
+ public:
+  H264DecoderImpl();
+  ~H264DecoderImpl() override;
+
+  bool Configure(const Settings& settings) override;
+  int32_t Release() override;
+
+  int32_t RegisterDecodeCompleteCallback(
+      DecodedImageCallback* callback) override;
+
+  // `missing_frames`, `fragmentation` and `render_time_ms` are ignored.
+  int32_t Decode(const EncodedImage& input_image,
+                 bool /*missing_frames*/,
+                 int64_t render_time_ms = -1) override;
+
+  const char* ImplementationName() const override;
+
+ private:
+  // Called by FFmpeg when it needs a frame buffer to store decoded frames in.
+  // The `VideoFrame` returned by FFmpeg at `Decode` originate from here. Their
+  // buffers are reference counted and freed by FFmpeg using `AVFreeBuffer2`.
+  static int AVGetBuffer2(AVCodecContext* context,
+                          AVFrame* av_frame,
+                          int flags);
+  // Called by FFmpeg when it is done with a video frame, see `AVGetBuffer2`.
+  static void AVFreeBuffer2(void* opaque, uint8_t* data);
+
+  bool IsInitialized() const;
+
+  // Reports statistics with histograms.
+  void ReportInit();
+  void ReportError();
+
+  // Used by ffmpeg via `AVGetBuffer2()` to allocate I420 images.
+  VideoFrameBufferPool ffmpeg_buffer_pool_;
+  std::unique_ptr<AVCodecContext, AVCodecContextDeleter> av_context_;
+  std::unique_ptr<AVFrame, AVFrameDeleter> av_frame_;
+
+  DecodedImageCallback* decoded_image_callback_;
+
+  bool has_reported_init_;
+  bool has_reported_error_;
+
+  webrtc::H264BitstreamParser h264_bitstream_parser_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_USE_H264
+
+#endif  // MODULES_VIDEO_CODING_CODECS_H264_H264_DECODER_IMPL_H_