做网站维护需要什么证书,怎么找做网站的客户,二十个知名品牌vi案例,电子网站模板在之前的学习中#xff0c;通过AVFrame来保存为图片来认识了AVFrame#xff0c;
[FFmpeg学习]从视频中获取图片_ffmpeg 获取图片-CSDN博客
在获取到AVFrame时#xff0c;还可以调用SDL方法来进行展现#xff0c;实现播放效果。
参考资料
SDL#xff0c;ffmpeg实现简单…在之前的学习中通过AVFrame来保存为图片来认识了AVFrame
[FFmpeg学习]从视频中获取图片_ffmpeg 获取图片-CSDN博客
在获取到AVFrame时还可以调用SDL方法来进行展现实现播放效果。
参考资料
SDLffmpeg实现简单视频播放器_ffmpeg sdl 播放器-CSDN博客
SDL2 简单介绍以及Windows开发环境搭建-CSDN博客
这里只显示了视频没有处理声音
// ffmpegTest.cpp : 此文件包含 main 函数。程序执行将在此处开始并结束。
//#include iostream/*
int main()
{std::cout Hello World!\n;
}*/extern C {
#include libavcodec/avcodec.h
#include libavformat/avformat.h
#include libavutil/log.h
#include libavformat/avformat.h
}using namespace std;//要使用FFmpeg库从MP4文件中提取一张图片你需要使用FFmpeg的解码器来读取视频帧并将其保存为图片。以下是一个简单的示例程序演示如何使用FFmpeg库从MP4文件中提取一张图片
#include stdio.h
#include stdlib.h
#include string.h #include SDL.hint savePicture(AVFrame* pFrame, char* out_name) {//编码保存图片int width pFrame-width;int height pFrame-height;AVCodecContext* pCodeCtx NULL;AVFormatContext* pFormatCtx avformat_alloc_context();// 设置输出文件格式pFormatCtx-oformat av_guess_format(mjpeg, NULL, NULL);// 创建并初始化输出AVIOContextif (avio_open(pFormatCtx-pb, out_name, AVIO_FLAG_READ_WRITE) 0) {printf(Couldnt open output file.);return -1;}// 构建一个新streamAVStream* pAVStream avformat_new_stream(pFormatCtx, 0);if (pAVStream NULL) {return -1;}AVCodecParameters* parameters pAVStream-codecpar;parameters-codec_id pFormatCtx-oformat-video_codec;parameters-codec_type AVMEDIA_TYPE_VIDEO;parameters-format AV_PIX_FMT_YUVJ420P;parameters-width pFrame-width;parameters-height pFrame-height;const AVCodec* pCodec avcodec_find_encoder(pAVStream-codecpar-codec_id); //查找编码器if (!pCodec) {printf(Could not find encoder\n);return -1;}pCodeCtx avcodec_alloc_context3(pCodec); //为AVCodecContext分配内存if (!pCodeCtx) {fprintf(stderr, Could not allocate video codec context\n);exit(1);}if ((avcodec_parameters_to_context(pCodeCtx, pAVStream-codecpar)) 0) {fprintf(stderr, Failed to copy %s codec parameters to decoder context\n,av_get_media_type_string(AVMEDIA_TYPE_VIDEO));return -1;}// AVRational tmp { 1, 25 };pCodeCtx-time_base { 1, 25 };if (avcodec_open2(pCodeCtx, pCodec, NULL) 0) { //打开编码器printf(Could not open codec.);return -1;}int ret avformat_write_header(pFormatCtx, NULL);if (ret 0) {printf(write_header fail\n);return -1;}int y_size width * height;//Encode// 给AVPacket分配足够大的空间AVPacket pkt;av_new_packet(pkt, y_size * 3);// 编码数据ret avcodec_send_frame(pCodeCtx, pFrame);if (ret 0) {printf(Could not avcodec_send_frame.);return -1;}// 得到编码后数据ret avcodec_receive_packet(pCodeCtx, pkt);if (ret 0) {printf(Could not avcodec_receive_packet);return -1;}ret av_write_frame(pFormatCtx, pkt);if (ret 0) {printf(Could not av_write_frame);return -1;}av_packet_unref(pkt);//Write Trailerav_write_trailer(pFormatCtx);avcodec_close(pCodeCtx);avio_close(pFormatCtx-pb);avformat_free_context(pFormatCtx);return 0;
}class SDLHandle
{
public:SDLHandle(int w, int h){m_rect.x 0;m_rect.y 0;m_rect.w w;m_rect.h h;SdlInit();}~SDLHandle(){if (m_pTexture){SDL_DestroyTexture(m_pTexture);}if (m_pRender){SDL_DestroyRenderer(m_pRender);}if (m_pWnd){SDL_DestroyWindow(m_pWnd);}SDL_Quit();}bool CreateSDLWindow(const char* title, Uint32 flag){m_pWnd SDL_CreateWindow(title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, m_rect.w, m_rect.h, flag);if (!m_pWnd){printf(CreateWindows error:%s.\n, SDL_GetError());return false;}m_pRender SDL_CreateRenderer(m_pWnd, -1, 0);if (!m_pRender){return false;}m_pTexture SDL_CreateTexture(m_pRender, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, m_rect.w, m_rect.h);if (!m_pTexture){return false;}return true;}void UpdateTexture(AVFrame* pFrame){if (!pFrame){return;}//SDL_UpdateTexture(m_pTexture, m_rect, pFrame-data[0], pFrame-linesize[0]);SDL_UpdateYUVTexture(m_pTexture, m_rect, pFrame-data[0], pFrame-linesize[0], pFrame-data[1], pFrame-linesize[1], pFrame-data[2], pFrame-linesize[2]);SDL_RenderClear(m_pRender);SDL_RenderCopy(m_pRender, m_pTexture, nullptr, m_rect);SDL_RenderPresent(m_pRender);SDL_Delay(40);}
private:bool SdlInit(){if (SDL_Init(SDL_INIT_AUDIO | SDL_INIT_VIDEO | SDL_INIT_TIMER) 0){printf(sdl_init error:%s\n, SDL_GetError());return false;}return true;}
private:SDL_Renderer* m_pRender nullptr;SDL_Window* m_pWnd nullptr;SDL_Texture* m_pTexture nullptr;SDL_Rect m_rect;
};int getpic4() {std::string filename test.mp4; // 输入MP4文件名std::string outputFilename output4.jpg; // 输出图片文件名SDL_Window* pScreen nullptr; // 播放窗口SDL_Renderer* pRender nullptr; // 渲染器SDL_Texture* pSDLTexture nullptr; // 纹理SDLHandle* m_pSDlHandle nullptr;AVFormatContext* formatContext nullptr;if (avformat_open_input(formatContext, filename.c_str(), nullptr, nullptr) ! 0) {std::cerr Error opening input file std::endl;return -1;}if (avformat_find_stream_info(formatContext, nullptr) 0) {std::cerr Error finding stream information std::endl;avformat_close_input(formatContext);return -1;}const AVCodec* codec nullptr;int videoStreamIndex -1;for (unsigned int i 0; i formatContext-nb_streams; i) {if (formatContext-streams[i]-codecpar-codec_type AVMEDIA_TYPE_VIDEO) {videoStreamIndex i;codec avcodec_find_decoder(formatContext-streams[i]-codecpar-codec_id);break;}}if (videoStreamIndex -1 || codec nullptr) {std::cerr Error finding video stream or decoder std::endl;avformat_close_input(formatContext);return -1;}AVCodecContext* codecContext avcodec_alloc_context3(codec);if (codecContext nullptr) {std::cerr Error allocating codec context std::endl;avformat_close_input(formatContext);return -1;}if (avcodec_parameters_to_context(codecContext, formatContext-streams[videoStreamIndex]-codecpar) 0) {std::cerr Error setting codec parameters std::endl;avcodec_free_context(codecContext);avformat_close_input(formatContext);return -1;}if (avcodec_open2(codecContext, codec, nullptr) 0) {std::cerr Error opening codec std::endl;avcodec_free_context(codecContext);avformat_close_input(formatContext);return -1;}m_pSDlHandle new SDLHandle(codecContext-width, codecContext-height);if (!m_pSDlHandle-CreateSDLWindow(SDL_TEXT, SDL_WINDOW_OPENGL)){printf(CreateSDLWindow error:%s\n, SDL_GetError());return -1;}AVPacket packet;av_init_packet(packet);// 查找目标时间戳所对应的帧AVFrame* frame av_frame_alloc();bool foundTargetFrame false;int count 0;while (av_read_frame(formatContext, packet) 0) {if (packet.stream_index videoStreamIndex) {int response avcodec_send_packet(codecContext, packet);if (response 0) {std::cerr Error sending packet to decoder std::endl;break;}count;response avcodec_receive_frame(codecContext, frame);if (response AVERROR(EAGAIN) || response AVERROR_EOF) {continue;}else if (response 0) {std::cerr Error receiving frame from decoder std::endl;break;}m_pSDlHandle-UpdateTexture(frame);}av_packet_unref(packet);}if (!foundTargetFrame) {std::cerr Target frame not found std::endl;av_frame_free(frame);avcodec_free_context(codecContext);avformat_close_input(formatContext);return -1;}// 清理资源av_frame_free(frame);av_packet_unref(packet);avcodec_free_context(codecContext);return 1;
}#undef main
int main(int argc, char* argv[]) {av_log(NULL, AV_LOG_INFO, ...Hello world\n);getpic4();return 0;
}
