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/*
* 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
// 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 <libavcodec/avcodec.h>
} // extern "C"
#include <memory>
#include "common_video/h264/h264_bitstream_parser.h"
#include "common_video/include/video_frame_buffer_pool.h"
#include "modules/video_coding/codecs/h264/include/h264.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_
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