采集摄像头

  1. ffmpeg -f video4linux2 -s  640x480 -pixel_format yuyv422  -i /dev/video1  out.mp4 -loglevel debug

采集桌面

  1. ffmpeg 需要使能: --enable-libxcb
  3. ffmpeg -f x11grab -framerate 25 -video_size 1280*720 -i :0.0 out.mp4

采集桌面（树莓派）

ffmpeg -f x11grab -s 1280x720 -i :0.0 -f alsa -i hw:0,0 -f flv out.mp4

采集桌面&摄像头的画面，并保存为YUV420P格式

  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <stdlib.h>
  4. #include <unistd.h>
  5. #include <fstream>
  6. #include <iostream>
  7. using namespace std;
  9. extern "C"
  10. {
  11. #include <libavutil/log.h>
  12. #include <libavcodec/avcodec.h>
  13. #include <libavformat/avformat.h>
  14. #include <libavdevice/avdevice.h>
  15. #include <libswscale/swscale.h>
  16. #include <libavutil/imgutils.h>
  17. }
  19. #define YUV420P_DUMP
  20. int main(int argc, char *argv[])
  21. {
  22.     av_log_set_level(AV_LOG_INFO);
  24.     if(argc < 3|| strlen(argv[1]) == 0 || strlen(argv[2]) == 0 )
  25.     {
  26.         av_log(nullptr, AV_LOG_ERROR, "usage: ./FFrecorder format filename.\n");
  27.         av_log(nullptr, AV_LOG_ERROR, "for camera: ./FFrecorder video4linux2 /dev/video0.\n");
  28.         av_log(nullptr, AV_LOG_ERROR, "for screen: ./FFrecorder x11grab :0.0 .\n");
  29.         return -1;
  30.     }
  32.     avcodec_register_all();
  33.     avdevice_register_all();
  35.     AVInputFormat *pInputFmt;
  36.     AVDictionary *pOptions =nullptr;
  37.     AVFormatContext *pFmtCtx = nullptr;
  38.     AVCodecContext    *pCodecCtx =nullptr;
  39.     AVCodec *pCodec =nullptr;
  40.     struct SwsContext *pSwsCtx=nullptr;
  42.     AVPacket *pPacket = nullptr;
  43.     AVFrame    *pFrame = nullptr;
  44.     AVFrame *pYUVFrame = nullptr;
  46.     int vieoStreamIndex = -1;
  47.     int retValue = 0;
  48.     int bGotFrame = 0;
  49.     int frameCnt = 10;
  50.     pInputFmt = av_find_input_format(argv[1]);
  51.     if(pInputFmt == nullptr)
  52.     {
  53.         av_log(nullptr, AV_LOG_ERROR, "cant not find input format.\n");
  54.         return -2;
  55.     }
  57.     if(strcmp(argv[1],"video4linux2") == 0)
  58.     {
  59.         av_dict_set(&pOptions, "video_size", "1280*720", AV_DICT_MATCH_CASE);
  60.         av_dict_set(&pOptions, "framerate", "10", AV_DICT_MATCH_CASE);
  61.     }
  62.     else if (strcmp(argv[1],"x11grab") == 0)
  63.     {
  64.         av_dict_set(&pOptions, "video_size", "1280*720", AV_DICT_MATCH_CASE);
  65.         av_dict_set(&pOptions, "framerate", "10", AV_DICT_MATCH_CASE);
  66.     }
  68.     if (avformat_open_input ( &pFmtCtx, argv[2], pInputFmt , &pOptions) < 0){
  69.         av_log(nullptr, AV_LOG_ERROR, "cant not open input file.\n");
  70.         return -3;
  71.     }
  73.     /* print device information*/
  74.     av_dump_format(pFmtCtx, 0, argv[2], 0);
  76.     if(avformat_find_stream_info(pFmtCtx, nullptr)<0)
  77.     {
  78.         av_log(nullptr, AV_LOG_ERROR, "cant not find stream information.\n");
  79.         return -4;
  80.     }
  82.     vieoStreamIndex = -1;
  83.     for(int iter=0; iter < static_cast<int>(pFmtCtx->nb_streams); iter++)
  84.     {
  85.         if(pFmtCtx->streams[iter]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
  86.         {
  87.             vieoStreamIndex=iter;
  88.             break;
  89.         }
  90.     }
  92.     if(vieoStreamIndex == -1){
  93.         av_log(nullptr, AV_LOG_ERROR, "cant not find a video stream.\n");
  94.         return -5;
  95.     }
  97.     pCodecCtx=pFmtCtx->streams[vieoStreamIndex]->codec;
  98.     pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  99.     if(pCodec==nullptr){
  100.         av_log(nullptr, AV_LOG_ERROR, "cant not find codec.\n");
  101.         return -6;
  102.     }
  103.     av_log(NULL, AV_LOG_INFO, "using codec:%s.\n", pCodec->name);
  104.     if(avcodec_open2(pCodecCtx, pCodec, nullptr)<0)
  105.     {
  106.         av_log(nullptr, AV_LOG_ERROR, "cant not open codec.\n");
  107.         return -7;
  108.     }
  110.     pSwsCtx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
  111.                              pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P,
  112.                              SWS_BICUBIC, nullptr, nullptr, nullptr);
  115. #ifdef YUV420P_DUMP
  116.     ofstream out_image("video.yuv", ios::binary);
  117.     if (!out_image.is_open())
  118.     {
  119.         av_log(nullptr, AV_LOG_ERROR, "Failed to save yuv video: %s\n", "video.yuv");
  120.         return -8;
  121.     }
  122. #endif
  124.     pPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
  125.     pFrame = av_frame_alloc();
  126.     pYUVFrame =  av_frame_alloc();
  127.     uint8_t *pYUVFrameBuffer = (uint8_t *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1));
  128.     av_image_fill_arrays(pYUVFrame->data, pYUVFrame->linesize, pYUVFrameBuffer,
  129.                          AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1);
  130.     pYUVFrame->format = AV_PIX_FMT_YUV420P;
  132.     while(av_read_frame(pFmtCtx, pPacket)>=0)
  133.     {
  134.         if(pPacket->stream_index == vieoStreamIndex)
  135.         {
  136.             retValue = avcodec_decode_video2(pCodecCtx, pFrame, &bGotFrame, pPacket);
  137.             if(retValue < 0){
  138.                 av_log(nullptr, AV_LOG_ERROR, "decode a frame error.\n");
  139.                 break;
  140.             }
  141.             if(bGotFrame)
  142.             {
  143.                 av_log(nullptr, AV_LOG_INFO, "get a frame.\n");
  144.                 sws_scale(pSwsCtx, static_cast<const uint8_t *const *>(pFrame->data), pFrame->linesize, 0,
  145.                           pCodecCtx->height, pYUVFrame->data, pYUVFrame->linesize);
  146.                 //av_log(nullptr, AV_LOG_INFO, "pFrame->format %d.\n", pFrame->format );
  147.                 //av_log(nullptr, AV_LOG_INFO, "pYUVFrame->format %d.\n", pYUVFrame->format );
  148.                 if (static_cast<AVPixelFormat>(pYUVFrame->format) == AV_PIX_FMT_YUV420P)
  149.                 {
  150. #ifdef YUV420P_DUMP
  151.                     int y_size = pCodecCtx->width * pCodecCtx->height;
  152.                     out_image.write((char *)pYUVFrame->data[0], y_size);
  153.                     out_image.write((char *)pYUVFrame->data[1], y_size / 4);
  154.                     out_image.write((char *)pYUVFrame->data[2], y_size / 4);
  155.                     //av_log(nullptr, AV_LOG_INFO, "write a frame.\n");
  156. #endif
  157.                 }
  158.                 frameCnt--;
  159.             }
  160.             if(frameCnt == 0)
  161.             {
  162.                 break;
  163.             }
  164.         }
  165.     }
  167. #ifdef YUV420P_DUMP
  168.     out_image.close();
  169. #endif
  170.     sws_freeContext(pSwsCtx);
  171.     av_free(pYUVFrameBuffer);
  172.     av_free(pPacket);
  173.     av_free(pYUVFrame);
  174.     av_free(pFrame);
  175.     avcodec_close(pCodecCtx);
  176.     avformat_close_input(&pFmtCtx);
  177.     av_free(pFmtCtx);
  178.     return 0;
  179. }
  183. ######################################
  184. #
  185. ######################################
  186. #source file
  187. #源文件，自动找所有.c和.cpp文件，并将目标定义为同名.o文件
  188. SOURCE  := $(wildcard *.c) $(wildcard *.cpp)
  189. OBJS    := $(patsubst %.c,%.o,$(patsubst %.cpp,%.o,$(SOURCE)))
  191. #target you can change test to what you want
  192. #目标文件名，输入任意你想要的执行文件名
  193. TARGET  := FFrecorder
  195. #compile and lib parameter
  196. #编译参数
  197. CXX     := g++
  198. LIBS    := -L /usr/local/lib -lavformat -lavutil -lavdevice -lavcodec -lswresample -lavfilter -lswscale -pthread
  199. LDFLAGS :=
  200. DEFINES := 
  201. INCLUDE := -I.
  202. CFLAGS  := -g -Wall  -O3 -std=c11 $(DEFINES) $(INCLUDE)
  203. CXXFLAGS:=  -g -Wall  -O3 -std=c++11 $(DEFINES) $(INCLUDE)
  206. #i think you should do anything here
  207. #下面的基本上不需要做任何改动了
  208. .PHONY : everything objs clean veryclean rebuild
  210. everything : $(TARGET)
  212. all : $(TARGET)
  214. objs : $(OBJS)
  216. rebuild: veryclean everything
  218. clean :
  219.     rm -fr *.so
  220.     rm -fr *.o
  222. veryclean : clean
  223.     rm -fr $(TARGET)
  225. $(TARGET) : $(OBJS)
  226.     $(CXX) $(CXXFLAGS) -o $@ $(OBJS) $(LDFLAGS) $(LIBS)

FFMPEG（一） 从V4L2捕获摄像头数据
FFmpeg接口-AVDictionary的使用介绍和源码分析