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SDL2绘制ffmpeg解析的mp4文件
本项目采用生产者消费者模型，生产者线程：使用ffmpeg将mp4格式数据解析为yuv的帧，消费者线程：利用sdl2将解析的yuv的帧进行消费，绘制到屏幕上。未完成的部分：1.解析音频数据，并与视频数据同步。2.增加界面：暂停，播放按钮，支持视频前进和后退。
学习音视频的参考资料与项目：
playdemo_github
雷神的csdn博客
1.FFMPEG利用命令行将mp4转yuv420
ffmpeg -i input.mp4 -c:v rawvideo -pix_fmt yuv420p output.yuv
2.ffmpeg将mp4解析为yuv数据
2.1 核心api:
- av_read_frame:读取一帧数据
- avcodec_send_packet:将数据包发送给解码器
- avcodec_receive_frame:将数据包从解码器中取
- sws_scale:格式转换，将解码后的帧数据转为yuv数据，存储在data[0],data[1],data[2]中
void readFrame() { AVPacket* avPacket = av_packet_alloc(); AVFrame* frame = av_frame_alloc(); FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data","wb+") ; while (av_read_frame(formatContext, avPacket) >= 0 && fp) { if (avPacket->stream_index == videoStreamIndex) { if (avcodec_send_packet(codecContext, avPacket) < 0) { std::cerr << "发送数据包到解码器失败" << std::endl; break; } /*解码*/ int ret = avcodec_receive_frame(codecContext, frame); printf("ret:%d\n", ret); if (ret >= 0) { ret = sws_scale(swsContext, frame->data, frame->linesize, 0, codecContext->height, yuvFrame->data, yuvFrame->linesize); printf("sws_scale ret=%d\n", ret); std::lock_guard<std::mutex>lck(mtx); isFinished = false; memcpy(yuvBuf, yuvFrame->data[0], yuvFrame->width * yuvFrame->height); memcpy(yuvBuf + yuvFrame->width * yuvFrame->height, yuvFrame->data[1], yuvFrame->width * yuvFrame->height / 4); memcpy(yuvBuf + yuvFrame->width * yuvFrame->height*5/4, yuvFrame->data[2], yuvFrame->width * yuvFrame->height / 4); isFinished = true; condvar.notify_one(); //保存y分量 //fwrite(yuvFrame->data[0], 1, yuvFrame->width * yuvFrame->height, fp); //保存uv分量 //fwrite(yuvFrame->data[1], 1, yuvFrame->width * yuvFrame->height/4, fp); //fwrite(yuvFrame->data[2], 1, yuvFrame->width * yuvFrame->height / 4, fp); } } } fclose(fp); av_frame_unref(yuvFrame); av_packet_free(&avPacket); av_frame_unref(frame); }- 1
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3.SDL2进行yuv绘制到屏幕
3.1 核心api
- SDL_Init
- SDL_CreateWindow
- SDL_CreateRenderer
- SDL_CreateTexture
- SDL_UpdateTexture
- SDL_RenderCopy
- SDL_RenderPresent
- SDL_Delay:控制帧率
int sdl_display() { if (SDL_Init(SDL_INIT_VIDEO)) { printf("sdl init failed\n"); return -1; } SDL_Window* window = SDL_CreateWindow("sdl_demo", 200, 200, codecContext->width, codecContext->height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE); if (!window) { SDL_Quit(); return -1; } SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0); if (!renderer) { SDL_DestroyWindow(window); SDL_Quit(); return -1; } SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); SDL_RenderClear(renderer); Uint32 pixformat = SDL_PIXELFORMAT_IYUV; SDL_Texture* sdlTexture = SDL_CreateTexture(renderer, pixformat, SDL_TEXTUREACCESS_STREAMING, codecContext->width, codecContext->height); //FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data", "rb+"); while (1) { //int ret = fread(yuvBuf, 1, yuvlen, fp); //if (ret <= 0) { // break; //} std::unique_lock<std::mutex>lck(mtx); if (condvar.wait_for(lck, std::chrono::seconds(1), [] { return isFinished;})) { isFinished = false; SDL_UpdateTexture(sdlTexture, NULL, yuvBuf, codecContext->width); SDL_RenderCopy(renderer, sdlTexture, NULL, NULL); SDL_RenderPresent(renderer); //控制帧率25fps SDL_Delay(40); } else { printf("sdl thread exit!\n"); break; } } SDL_Quit(); return 0; }- 1
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4.完整代码
-使用两个线程，生产者消费者模型
#include#include #include #include #include #include #include #include #include #include extern "C" { #include #include #include #include #include } #undef main #pragma warning(disable:4996) AVFormatContext* formatContext = nullptr; AVCodecContext* codecContext = nullptr; SwsContext* swsContext = nullptr; int videoStreamIndex = -1; AVFrame* yuvFrame; unsigned char* yuvBuf; bool isReady = false; bool isFinished = false; std::mutex mtx; std::condition_variable condvar; void readFrame() { AVPacket* avPacket = av_packet_alloc(); AVFrame* frame = av_frame_alloc(); FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data","wb+") ; while (av_read_frame(formatContext, avPacket) >= 0 && fp) { if (avPacket->stream_index == videoStreamIndex) { if (avcodec_send_packet(codecContext, avPacket) < 0) { std::cerr << "发送数据包到解码器失败" << std::endl; break; } /*解码*/ int ret = avcodec_receive_frame(codecContext, frame); printf("ret:%d\n", ret); if (ret >= 0) { ret = sws_scale(swsContext, frame->data, frame->linesize, 0, codecContext->height, yuvFrame->data, yuvFrame->linesize); printf("sws_scale ret=%d\n", ret); std::lock_guard<std::mutex>lck(mtx); isFinished = false; memcpy(yuvBuf, yuvFrame->data[0], yuvFrame->width * yuvFrame->height); memcpy(yuvBuf + yuvFrame->width * yuvFrame->height, yuvFrame->data[1], yuvFrame->width * yuvFrame->height / 4); memcpy(yuvBuf + yuvFrame->width * yuvFrame->height*5/4, yuvFrame->data[2], yuvFrame->width * yuvFrame->height / 4); isFinished = true; condvar.notify_one(); //保存y分量 //fwrite(yuvFrame->data[0], 1, yuvFrame->width * yuvFrame->height, fp); //保存uv分量 //fwrite(yuvFrame->data[1], 1, yuvFrame->width * yuvFrame->height/4, fp); //fwrite(yuvFrame->data[2], 1, yuvFrame->width * yuvFrame->height / 4, fp); } } } fclose(fp); av_frame_unref(yuvFrame); av_packet_free(&avPacket); av_frame_unref(frame); } int sdl_display() { if (SDL_Init(SDL_INIT_VIDEO)) { printf("sdl init failed\n"); return -1; } SDL_Window* window = SDL_CreateWindow("sdl_demo", 200, 200, codecContext->width, codecContext->height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE); if (!window) { SDL_Quit(); return -1; } SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0); if (!renderer) { SDL_DestroyWindow(window); SDL_Quit(); return -1; } SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); SDL_RenderClear(renderer); Uint32 pixformat = SDL_PIXELFORMAT_IYUV; SDL_Texture* sdlTexture = SDL_CreateTexture(renderer, pixformat, SDL_TEXTUREACCESS_STREAMING, codecContext->width, codecContext->height); //FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data", "rb+"); while (1) { //int ret = fread(yuvBuf, 1, yuvlen, fp); //if (ret <= 0) { // break; //} std::unique_lock<std::mutex>lck(mtx); if (condvar.wait_for(lck, std::chrono::seconds(1), [] { return isFinished;})) { isFinished = false; SDL_UpdateTexture(sdlTexture, NULL, yuvBuf, codecContext->width); SDL_RenderCopy(renderer, sdlTexture, NULL, NULL); SDL_RenderPresent(renderer); //控制帧率25fps SDL_Delay(40); } else { printf("sdl thread exit!\n"); break; } } SDL_Quit(); return 0; } /*ffmpeg -i input.mp4 -c:v rawvideo -pix_fmt yuv420p output.yuv*/ int main(int argc, char* argv[]) { /*if (argc != 2) { std::cerr << "文件名未指定" << std::endl; return -1; }*/ std::string filename = "F:/VS_Project/ffmpeg_demo/1.mkv"; if (avformat_open_input(&formatContext, filename.c_str(), nullptr, nullptr) != 0) { std::cerr << "无法打开文件" << std::endl; return -1; } if (avformat_find_stream_info(formatContext, nullptr) < 0) { std::cerr << "无法找到视频流" << std::endl; return -1; } for (int i = 0; i < formatContext->nb_streams; i++) { enum AVMediaType type = AVMEDIA_TYPE_VIDEO; AVStream* st = formatContext->streams[i]; AVCodecParameters* codecpar = st->codecpar; if (codecpar->codec_type == type) { videoStreamIndex = i; const AVCodec* codec = avcodec_find_decoder(codecpar->codec_id); codecContext = avcodec_alloc_context3(codec); avcodec_parameters_to_context(codecContext, codecpar); avcodec_open2(codecContext, codec, nullptr); swsContext = sws_getContext(codecContext->width, codecContext->height, codecContext->pix_fmt, codecContext->width, codecContext->height, AV_PIX_FMT_YUV420P, SWS_BILINEAR, nullptr, nullptr, nullptr); std::cout << "w:" << codecpar->width << std::endl; std::cout << "h:" << codecpar->height << std::endl; } } yuvFrame = av_frame_alloc(); yuvFrame->width = codecContext->width; yuvFrame->height = codecContext->height; yuvFrame->format = AV_PIX_FMT_YUV420P; int yuvlen = codecContext->width * codecContext->height * 3 / 2; yuvBuf = new unsigned char[yuvlen]; int ret = av_frame_get_buffer(yuvFrame, 0); if (ret < 0) { printf("分配缓冲区失败\n"); return -1; } //sdl_init(); std::thread th1(readFrame); std::thread th2(sdl_display); th1.join(); th2.join(); delete[]yuvBuf; return 0; } - 1
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5.效果展示
6.SDL2事件响应补充
6.1 处理方式-01
起一个refresh_video线程，用于产生一个自定义更新video的事件：REFRESH_EVENT，并且每40ms更新一次。while循环中持续等待事件的到来：SDL_WaitEvent，当收到事件后更新一帧画面。同时当监测到窗口改变的事件，SDL_GetWindowSize对窗口进行调整。
int refresh_video(void *opaque){ thread_exit=0; while (thread_exit==0) { SDL_Event event; event.type = REFRESH_EVENT; SDL_PushEvent(&event); SDL_Delay(40); } thread_exit=0; //Break SDL_Event event; event.type = BREAK_EVENT; SDL_PushEvent(&event); return 0; } SDL_Thread *refresh_thread = SDL_CreateThread(refresh_video,NULL,NULL); SDL_Event event; while(1){ //Wait SDL_WaitEvent(&event); if(event.type==REFRESH_EVENT){ if (fread(buffer, 1, pixel_w*pixel_h*bpp/8, fp) != pixel_w*pixel_h*bpp/8){ // Loop fseek(fp, 0, SEEK_SET); fread(buffer, 1, pixel_w*pixel_h*bpp/8, fp); } SDL_UpdateTexture( sdlTexture, NULL, buffer, pixel_w); //FIX: If window is resize sdlRect.x = 0; sdlRect.y = 0; sdlRect.w = screen_w; sdlRect.h = screen_h; SDL_RenderClear( sdlRenderer ); SDL_RenderCopy( sdlRenderer, sdlTexture, NULL, &sdlRect); SDL_RenderPresent( sdlRenderer ); }else if(event.type==SDL_WINDOWEVENT){ //If Resize SDL_GetWindowSize(screen,&screen_w,&screen_h); }else if(event.type==SDL_QUIT){ thread_exit=1; }else if(event.type==BREAK_EVENT){ break; } } SDL_Quit();- 1
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6.2 处理方式-02
起一个事件循环线程，SDL_PeepEvents 从事件队列中取出一个事件，然后更新事件队列，并进行绘制操作。
//播放控制循环 void VideoCtl::LoopThread(VideoState *cur_stream) { SDL_Event event; double incr, pos, frac; m_bPlayLoop = true; while (m_bPlayLoop) { double x; refresh_loop_wait_event(cur_stream, &event); switch (event.type) { case SDL_KEYDOWN: switch (event.key.keysym.sym) { case SDLK_s: // S: Step to next frame step_to_next_frame(cur_stream); break; case SDLK_a: stream_cycle_channel(cur_stream, AVMEDIA_TYPE_AUDIO); break; case SDLK_v: stream_cycle_channel(cur_stream, AVMEDIA_TYPE_VIDEO); break; case SDLK_c: stream_cycle_channel(cur_stream, AVMEDIA_TYPE_VIDEO); stream_cycle_channel(cur_stream, AVMEDIA_TYPE_AUDIO); stream_cycle_channel(cur_stream, AVMEDIA_TYPE_SUBTITLE); break; case SDLK_t: stream_cycle_channel(cur_stream, AVMEDIA_TYPE_SUBTITLE); break; default: break; } break; case SDL_WINDOWEVENT: //窗口大小改变事件 qDebug()<<"SDL_WINDOWEVENT "<<endl; switch (event.window.event) { case SDL_WINDOWEVENT_RESIZED: screen_width = cur_stream->width = event.window.data1; screen_height = cur_stream->height = event.window.data2; case SDL_WINDOWEVENT_EXPOSED: cur_stream->force_refresh = 1; } break; case SDL_QUIT: case FF_QUIT_EVENT: do_exit(cur_stream); break; default: break; } } do_exit(m_CurStream); //m_CurStream = nullptr; }- 1
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- 原文地址：https://blog.csdn.net/Wwc_code/article/details/133524976
