1 /* 2 * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 * 10 */ 11 12 #ifndef MODULES_VIDEO_CODING_CODECS_H264_H264_DECODER_IMPL_H_ 13 #define MODULES_VIDEO_CODING_CODECS_H264_H264_DECODER_IMPL_H_ 14 15 // Everything declared in this header is only required when WebRTC is 16 // build with H264 support, please do not move anything out of the 17 // #ifdef unless needed and tested. 18 #ifdef WEBRTC_USE_H264 19 20 #if defined(WEBRTC_WIN) && !defined(__clang__) 21 #error "See: bugs.webrtc.org/9213#c13." 22 #endif 23 24 #include <memory> 25 26 #include "modules/video_coding/codecs/h264/include/h264.h" 27 28 // CAVEAT: According to ffmpeg docs for avcodec_send_packet, ffmpeg requires a 29 // few extra padding bytes after the end of input. And in addition, docs for 30 // AV_INPUT_BUFFER_PADDING_SIZE says "If the first 23 bits of the additional 31 // bytes are not 0, then damaged MPEG bitstreams could cause overread and 32 // segfault." 33 // 34 // WebRTC doesn't ensure any such padding, and REQUIRES ffmpeg to be compiled 35 // with CONFIG_SAFE_BITSTREAM_READER, which is intended to eliminate 36 // out-of-bounds reads. ffmpeg docs doesn't say explicitly what effects this 37 // flag has on the h.264 decoder or avcodec_send_packet, though, so this is in 38 // some way depending on undocumented behavior. If any problems turn up, we may 39 // have to add an extra copy operation, to enforce padding before buffers are 40 // passed to ffmpeg. 41 42 extern "C" { 43 #include "third_party/ffmpeg/libavcodec/avcodec.h" 44 } // extern "C" 45 46 #include "common_video/h264/h264_bitstream_parser.h" 47 #include "common_video/include/video_frame_buffer_pool.h" 48 49 namespace webrtc { 50 51 struct AVCodecContextDeleter { operatorAVCodecContextDeleter52 void operator()(AVCodecContext* ptr) const { avcodec_free_context(&ptr); } 53 }; 54 struct AVFrameDeleter { operatorAVFrameDeleter55 void operator()(AVFrame* ptr) const { av_frame_free(&ptr); } 56 }; 57 58 class H264DecoderImpl : public H264Decoder { 59 public: 60 H264DecoderImpl(); 61 ~H264DecoderImpl() override; 62 63 bool Configure(const Settings& settings) override; 64 int32_t Release() override; 65 66 int32_t RegisterDecodeCompleteCallback( 67 DecodedImageCallback* callback) override; 68 69 // `missing_frames`, `fragmentation` and `render_time_ms` are ignored. 70 int32_t Decode(const EncodedImage& input_image, 71 bool /*missing_frames*/, 72 int64_t render_time_ms = -1) override; 73 74 const char* ImplementationName() const override; 75 76 private: 77 // Called by FFmpeg when it needs a frame buffer to store decoded frames in. 78 // The `VideoFrame` returned by FFmpeg at `Decode` originate from here. Their 79 // buffers are reference counted and freed by FFmpeg using `AVFreeBuffer2`. 80 static int AVGetBuffer2(AVCodecContext* context, 81 AVFrame* av_frame, 82 int flags); 83 // Called by FFmpeg when it is done with a video frame, see `AVGetBuffer2`. 84 static void AVFreeBuffer2(void* opaque, uint8_t* data); 85 86 bool IsInitialized() const; 87 88 // Reports statistics with histograms. 89 void ReportInit(); 90 void ReportError(); 91 92 // Used by ffmpeg via `AVGetBuffer2()` to allocate I420 images. 93 VideoFrameBufferPool ffmpeg_buffer_pool_; 94 std::unique_ptr<AVCodecContext, AVCodecContextDeleter> av_context_; 95 std::unique_ptr<AVFrame, AVFrameDeleter> av_frame_; 96 97 DecodedImageCallback* decoded_image_callback_; 98 99 bool has_reported_init_; 100 bool has_reported_error_; 101 102 webrtc::H264BitstreamParser h264_bitstream_parser_; 103 }; 104 105 } // namespace webrtc 106 107 #endif // WEBRTC_USE_H264 108 109 #endif // MODULES_VIDEO_CODING_CODECS_H264_H264_DECODER_IMPL_H_ 110