裸指针包装

/* Define unique_ptrs to auto-cleanup associated ffmpeg objects. */
struct AVIOContextDeleter {void operator()(AVIOContext *ptr) { avio_closep(&ptr); }
};
using AVIOContextPtr = std::unique_ptr<AVIOContext,AVIOContextDeleter>;struct AVFormatCtxDeleter {void operator()(AVFormatContext *ptr) { avformat_close_input(&ptr); }
};
using AVFormatCtxPtr = std::unique_ptr<AVFormatContext,AVFormatCtxDeleter>;struct AVCodecCtxDeleter {void operator()(AVCodecContext *ptr) { avcodec_free_context(&ptr); }
};
using AVCodecCtxPtr = std::unique_ptr<AVCodecContext,AVCodecCtxDeleter>;struct AVPacketDeleter {void operator()(AVPacket *pkt) { av_packet_free(&pkt); }
};
using AVPacketPtr = std::unique_ptr<AVPacket,AVPacketDeleter>;struct AVFrameDeleter {void operator()(AVFrame *ptr) { av_frame_free(&ptr); }
};
using AVFramePtr = std::unique_ptr<AVFrame,AVFrameDeleter>;struct SwrContextDeleter {void operator()(SwrContext *ptr) { swr_free(&ptr); }
};
using SwrContextPtr = std::unique_ptr<SwrContext,SwrContextDeleter>;struct SwsContextDeleter {void operator()(SwsContext *ptr) { sws_freeContext(ptr); }
};
using SwsContextPtr = std::unique_ptr<SwsContext,SwsContextDeleter>;

对象

struct ChannelLayout : public AVChannelLayout {ChannelLayout() : AVChannelLayout{} { }~ChannelLayout() { av_channel_layout_uninit(this); }
};

智能指针使用和轮子—解包队列

template<size_t SizeLimit>
class DataQueue {std::mutex mPacketMutex, mFrameMutex;std::condition_variable mPacketCond;std::condition_variable mInFrameCond, mOutFrameCond;std::deque<AVPacketPtr> mPackets;size_t mTotalSize{0};bool mFinished{false};AVPacketPtr getPacket(){std::unique_lock<std::mutex> plock{mPacketMutex};while(mPackets.empty() && !mFinished)mPacketCond.wait(plock);if(mPackets.empty())return nullptr;auto ret = std::move(mPackets.front());mPackets.pop_front();mTotalSize -= static_cast<unsigned int>(ret->size);return ret;}public:int sendPacket(AVCodecContext *codecctx){AVPacketPtr packet{getPacket()};int ret{};{std::unique_lock<std::mutex> flock{mFrameMutex};while((ret=avcodec_send_packet(codecctx, packet.get())) == AVERROR(EAGAIN))mInFrameCond.wait_for(flock, milliseconds{50});}mOutFrameCond.notify_one();if(!packet){if(!ret) return AVErrorEOF;std::cerr<< "Failed to send flush packet: "<<ret <<std::endl;return ret;}if(ret < 0)std::cerr<< "Failed to send packet: "<<ret <<std::endl;return ret;}int receiveFrame(AVCodecContext *codecctx, AVFrame *frame){int ret{};{std::unique_lock<std::mutex> flock{mFrameMutex};while((ret=avcodec_receive_frame(codecctx, frame)) == AVERROR(EAGAIN))mOutFrameCond.wait_for(flock, milliseconds{50});}mInFrameCond.notify_one();return ret;}void setFinished(){{std::lock_guard<std::mutex> _{mPacketMutex};mFinished = true;}mPacketCond.notify_one();}void flush(){{std::lock_guard<std::mutex> _{mPacketMutex};mFinished = true;mPackets.clear();mTotalSize = 0;}mPacketCond.notify_one();}bool put(const AVPacket *pkt){{std::unique_lock<std::mutex> lock{mPacketMutex};if(mTotalSize >= SizeLimit || mFinished)return false;mPackets.push_back(AVPacketPtr{av_packet_alloc()});if(av_packet_ref(mPackets.back().get(), pkt) != 0){mPackets.pop_back();return true;}mTotalSize += static_cast<unsigned int>(mPackets.back()->size);}mPacketCond.notify_one();return true;}
};