ffmpeg采集摄像头后解码并用framebuffer播放保存为bmp

FFmpeg解码流程&＃xff1a;

1、注册所有容器格式和CODEC&＃xff1a;avcodec_register_all()&＃xff1b;

2、查找对应的解码器&＃xff1a;avcodec_find_decoder(AV_CODEC_ID_MJPEG)&＃xff1b;

3、分配编解码器参数数据结构avcodec_alloc_context3(AVCodec *codec)&＃xff1b;

4、对于部分编解码需要对上一步分配的数据结构进行初始化&＃xff0c;因为某些参数在视频流中无效&＃xff1b;

5、打开编解码器&＃xff1a;avcodec_open2(AVCodecContext *ctx, AVCodec
*codec, NULL)&＃xff1b;

6、为解码帧分配内存&＃xff1a;AVFrame *frame &＃61; av_frame_alloc()&＃xff1b;

7、初始化编解码输入数据结构AVPacket&＃xff1a;av_init_packet(AVPacket
*packet)&＃xff1b;

8、将待解码的压缩视频数据放入数据结构AVPacket中&＃xff1a;

(AVPacket)packet.data &＃61; inbuf&＃xff08;待解码视频数据缓存&＃xff09;&＃xff1b;

(AVPacket)packet.size &＃61; inbufsize&＃xff08;待解码视频数据长度&＃xff09;&＃xff1b;

9、调用解码函数开始解码&＃xff1a;avcodec_decode_video2(AVCodecContext *ctx&＃xff0c;AVFrame *frame&＃xff0c;int *got&＃xff0c;AVPacket *packet)&＃xff1b;

10、拷贝解码后的一帧数据&＃xff0c;解码后的数据格式根据解码前的数据格式决定&＃xff0c;例如&＃xff0c;USB摄像头的MJPEG数据解码后是YUV422P格式&＃xff0c;H264格式数据解码后是YUV420P格式&＃xff1b;解码后的数据存放在AVFrame数据结构指向的缓存中&＃xff0c;存放方式为&＃xff1a;(AVFrame )frame->data[0]指向Y分量&＃xff0c;(AVFrame )frame->data[1]指向U分量&＃xff0c;(AVFrame )frame->data[2]指向V分量&＃xff1b;(AVFrame )frame->linesize[0]、(AVFrame )frame->linesize[1]、(AVFrame )frame->linesize[2]分别为Y、U、V分量每行的长度。

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#include struct options
{int frames;int nodec;int bplay;int thread_count;int64_t lstart;char finput[256];
};// check the video stream
static int find_video_stream(AVFormatContext* pCtx)
{int videoStream &＃61; -1;int i;// check the video streamfor (i &＃61; 0; i nb_streams; i&＃43;&＃43;){if (pCtx->streams[i]->codec->codec_type &＃61;&＃61; AVMEDIA_TYPE_VIDEO){videoStream &＃61; i;break;}}return videoStream;
}//save the BMP &＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;&＃43;
#pragma pack(1)
// 2byte
typedef struct bmp_magic
{unsigned char magic[2];
}magic_t;// 4 * 3 &＃61; 12 Byte
typedef struct bmp_header
{unsigned int file_size; //file size in Byte ,w * h * 3 &＃43; 54unsigned short creater1; //0unsigned short creater2; //0unsigned int offset; //offset to image data: 54D, 36H
}header_t ;typedef struct bmp_info
{unsigned int header_size; //info size in bytes, equals 4o D, or 28Hunsigned int width; //file wideth in pideunsigned int height; //file height in pideunsigned short nplanes; //number of clor planes , 1unsigned short bitspp; //bits per pidel, 24d, 18hunsigned int compress_type; //compress type,default 0unsigned int image_size; //image size in Byte. w * h * 3unsigned int hres; //pideles per meter, 0unsigned int vres; //pideles per meter, 0unsigned int ncolors; //number of colors, 0unsigned int nimpcolors; //important colors, 0
}info_t;int gen_bmp_header(unsigned char *head,unsigned w, unsigned h,unsigned bytepp)
{if(head&＃61;&＃61;NULL)return -1;magic_t magic;info_t info;header_t header;magic.magic[0] &＃61; &＃39;B&＃39;;magic.magic[1] &＃61; &＃39;M&＃39;;header.file_size &＃61; (w * h * bytepp &＃43; 54);header.creater1 &＃61; 0;header.creater2 &＃61; 0;header.offset &＃61; (54);info.header_size &＃61; (40);info.width &＃61; (w);info.height &＃61; (h);info.nplanes &＃61; (1);info.bitspp &＃61; (bytepp * 8);info.compress_type &＃61; 0;info.image_size &＃61; (w * h * bytepp);info.hres &＃61; 0;info.vres &＃61; 0;info.ncolors &＃61; 0;info.nimpcolors &＃61; 0;unsigned char *p&＃61;head;memcpy(p,&magic,sizeof(magic));p&＃43;&＃61;sizeof(magic);memcpy(p,&header,sizeof(header));p&＃43;&＃61;sizeof(header);memcpy(p,&info,sizeof(info));return 0;
} static void saveBitMap(AVFrame *pFrameRGB, int width, int height, int index, int bpp)
{unsigned char head[54];int i;FILE *fp &＃61; NULL;memset(head, 0, 54);gen_bmp_header(head,width, height,bpp/8);fp &＃61; fopen("./10.bmp", "w&＃43;");if (fp &＃61;&＃61; NULL){av_log(NULL, AV_LOG_INFO, "fopen BMP error\n");return ;}fwrite(head, 54, 1, fp);fwrite(pFrameRGB->data[0], width*height*bpp/8, 1, fp);fclose(fp);fp &＃61; NULL;
}
//save the BMP ---------------------------------------------------int main(int argc, char **argv)
{AVCodecContext *pCodecCtxVideo &＃61; 0;//videoAVCodec *pCodecVideo &＃61; 0;//videoAVPacket packet;AVFrame *pFrameVideo &＃61; 0;//videoAVFrame *pFrameRGB &＃61; 0;//save the RGB AVDictionary *options &＃61; NULL; FILE *fpo1 &＃61; NULL;FILE *fpo2 &＃61; NULL;int nframe;int err;struct options opt;int got_picture;int picwidth, picheight, linesize;unsigned char *pBuf;int i;int64_t timestamp;int usefo &＃61; 0;int dusecs;float usecs1 &＃61; 0;float usecs2 &＃61; 0;struct timeval elapsed1, elapsed2;int decoded &＃61; 0;int ret &＃61; -1;int videoStream &＃61; -1; av_register_all();avdevice_register_all();AVInputFormat *inputFormat &＃61; av_find_input_format("v4l2");AVFormatContext *pCtx&＃61;avformat_alloc_context();av_dict_set(&options,"video_size","640*480",0);err &＃61; avformat_open_input(&pCtx, "/dev/video0", NULL, &options);if (err <0){printf("\n->(avformat_open_input)\tERROR:\t%d\n", err);return -1;}printf("&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;&＃61;\n");err &＃61; avformat_find_stream_info(pCtx, 0);if (err <0){printf("\n->(avformat_find_stream_info)\tERROR:\t%d\n", err);return -1;}av_dump_format(pCtx, 0, opt.finput, 0);#if 1
// ************************VIDEO**********************************//// check the video streamvideoStream &＃61; find_video_stream(pCtx);if (videoStream <0){printf("there is not video stream !!!!!!! \n");return -1;}pCodecCtxVideo&＃61; pCtx->streams[videoStream]->codec;pCodecVideo &＃61; avcodec_find_decoder(pCodecCtxVideo->codec_id);if (!pCodecVideo){printf("\ncan&＃39;t find the video decoder!\n");return -1;}//open videoDecoderret &＃61; avcodec_open2(pCodecCtxVideo, pCodecVideo, 0);if (ret <0){printf("avcodec_open2 error(video) \n");return -1;}pFrameVideo &＃61; av_frame_alloc();pFrameRGB &＃61; av_frame_alloc();
//------------------------------------------------------------------------//
#endif int tmp &＃61; 10;//fb0 initopenframebuffer();init_fbmmap();while(av_read_frame(pCtx, &packet) >&＃61; 0){#if 1//found the video frame !!! if (packet.stream_index &＃61;&＃61; videoStream) { int got; int i;
#if 1avcodec_decode_video2(pCodecCtxVideo, pFrameVideo,&got_picture,&packet); printf("pFrameVideo->width &＃61; %d\n", pFrameVideo->width);printf("pFrameVideo->height &＃61; %d\n", pFrameVideo->height);printf("pFrameVideo->linesize[0] &＃61; %d\n", pFrameVideo->linesize[0]);printf("pFrameVideo->linesize[1] &＃61; %d\n", pFrameVideo->linesize[1]);printf("pFrameVideo->linesize[2] &＃61; %d\n", pFrameVideo->linesize[2]);
#endif//yuv420p -> rgb24int PictureSize &＃61; avpicture_get_size (AV_PIX_FMT_BGR24, pCodecCtxVideo->width, pCodecCtxVideo->height);void *buf &＃61; (uint8_t*)av_malloc(PictureSize);avpicture_fill ( (AVPicture *)pFrameRGB, buf,AV_PIX_FMT_BGR24, pCodecCtxVideo->width, pCodecCtxVideo->height);struct SwsContext* pSwsCxt &＃61; sws_getContext(pFrameVideo->width,pFrameVideo->height,pCodecCtxVideo->pix_fmt,pFrameVideo->width, pFrameVideo->height,AV_PIX_FMT_BGR24, SWS_BILINEAR,NULL,NULL,NULL);sws_scale(pSwsCxt,pFrameVideo->data,pFrameVideo->linesize,0,pFrameVideo->height,pFrameRGB->data, pFrameRGB->linesize);av_log(NULL, AV_LOG_INFO, "pFrameRGB->linesize[0] &＃61; %d\n", pFrameRGB->linesize[0]);//save the ARGB into BMP filesaveBitMap (pFrameRGB, pCodecCtxVideo->width, pCodecCtxVideo->height, 10, 24);fb_drawbmp(height, width, pFrame->data[0]); }
#endif }closefb();return 0;