文章目錄

• 0. 參考文獻
• 1. jpeg轉yuv
• 2. 源碼下載

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JPG和PNG等圖片的解碼方式和視頻解碼是一樣的，因為視頻是由一幅一幅的圖片組成的，只不過視頻的幀是會前后參考的，而JPG等圖片是單獨的一幀而已。

0. 參考文獻

ffmpeg解碼JPG和PNG等圖片

1. jpeg轉yuv

int main(int argc, char* argv[]) {int i;char szFileName[128] = { 0 };int decLen = 0;int frame = 0;AVCodecContext *pCodecCtx = NULL;AVFrame *pFrame = NULL;AVCodec *pCodec = NULL;AVFormatContext *pFormatCtx = NULL;/*if (argc != 3){fprintf(stderr, "ERROR:need 3 argument!n");exit(-1);}*/sprintf(szFileName, "%s", "H:/bmp2jpg/1.jpeg");#ifdef ENABLE_DEMUX_SAVEFILE* frvdemux = fopen("rvdemuxout.rm", "wb+");if (NULL == frvdemux){fprintf(stderr, "create rvdemuxout file failedn");exit(1);} #endif/* output yuv file name */sprintf(ffrvout, "%s", "H:/bmp2jpg/1.yuv");pfout = fopen(ffrvout, "wb+");if (NULL == pfout){printf("create output file failedn");exit(1);}printf("==========> Begin test ffmpeg call ffmpeg rv decodern");av_register_all();/* Open input video file *///printf("before avformat_open_input [%s]n", szFileName);if (avformat_open_input(&pFormatCtx, szFileName, NULL, NULL) != 0){fprintf(stderr, "Couldn't open input filen");return -1;}//printf("after avformat_open_inputn");/* Retrieve stream information */if (avformat_find_stream_info(pFormatCtx, 0) < 0){printf("av_find_stream_info ERRORn");return -1;}//printf("after av_find_stream_info, n");/* Find the first video stream */int videoStream = -1;printf("==========> pFormatCtx->nb_streams = %dn", pFormatCtx->nb_streams);for (i = 0; i < pFormatCtx->nb_streams; i++) {if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {videoStream = i;printf("the first video stream index: videoStream = %dn", videoStream);break;}}if (videoStream == -1)return -1; // Didn't find a video stream/* Get a pointer to the codec context for the video stream */pCodecCtx = pFormatCtx->streams[videoStream]->codec;printf("pCodecCtx->codec_id = %dn", pCodecCtx->codec_id);pCodec = avcodec_find_decoder(pCodecCtx->codec_id);if (pCodec == NULL) {fprintf(stderr, "can not find decoder!n");return -1;}/* Open codec */if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0){printf("cannot open software codecn");return -1; // Could not open codec}printf("==========> Open software codec successn");pFrame = av_frame_alloc();if (pFrame == NULL){fprintf(stderr, "avcodec_alloc_frame() ERRORn");return -1;}/* flag whether we get a decoded yuv frame */int frameFinished;int packetno = 0;AVPacket packet;av_init_packet(&packet);while (av_read_frame(pFormatCtx, &packet) >= 0) {//printf("[main]avpkt->slice_count=%dn", packet.sliceNum);/* Is this a packet from the video stream? */if (packet.stream_index == videoStream) {packetno++; #ifdef ENABLE_PRINT_FRAME_BYTESif (1) {int i;int size = packet.size < PRINT_BYTES ? packet.size : PRINT_BYTES;unsigned char *data = packet.data;printf("===>[%5d] [", packet.size);for (i = 0; i < size; i++)printf("%02x ", data[i]);printf("]n");} #endif #ifdef ENABLE_DEMUX_SAVEfwrite(packet.data, 1, packet.size, frvdemux); #endif//printf("[the %d packet]packet.size = %dn", packetno++, packet.size);while (packet.size > 0) {decLen = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);//printf("[video_decode_example]after avcodec_decode_video2,decoded=%dn",decLen);if (decLen < 0) {fprintf(stderr, "[video_decode_example]Error while decoding frame %dn", frame);//exit(1);/* FIXME if decode one frame err, ignore this frame */decLen = packet.size;}if (frameFinished) {printf("got a yuv framen");//printf(stderr, "[video_decode_example]saving frame %3dn", frame);/* the picture is allocated by the decoder. no need to free it */if (frame == 0) {printf("[video_decode_example]picture->linesize[0]=%d, c->width=%d,c->height=%dn",pFrame->linesize[0], pCodecCtx->width, pCodecCtx->height);printf("===>YUV format = %dn", pFrame->format);} #ifdef ENABLE_YUV_SAVE/* save yuv pic */if (frame < FRAME_NUM) {switch (pFrame->format) {case 0: /* YUV420P */case 12:yuv420p_save(pFrame, pCodecCtx);break;case 2: /* RGB24 */rgb24_save(pFrame, pCodecCtx);break;case 13: /* YUVJ422P */yuv422p_save(pFrame, pCodecCtx);break;case 14: /* YUVJ444P */yuv444p_save(pFrame, pCodecCtx);break;default:fprintf(stderr, "unsupport YUV format for savingn");break;}fprintf(stderr, "===>save pic successn");} #endif/* frame index grow */frame++;}//printf("===========> %dn", decLen);/* left data in pkt , go on decoding */packet.data += decLen;packet.size -= decLen;}if (frame == FRAME_NUM) {printf("==========> decoded [%d pkt frames] ---> save [%d YUV frames], enough to stop!n", packetno, FRAME_NUM);break;}}/* FIXME no need free in this file *///printf("free packet that was allocated by av_read_framen");// Free the packet that was allocated by av_read_frame//av_free_packet(&packet);}printf("decoding job down! begin to freen");/* Free the YUV frame */av_free(pFrame);/* Close the codec */avcodec_close(pCodecCtx);/* Close the video file */avformat_free_context(pFormatCtx);fclose(pfout);printf("==========> END-OKn");return 0; }

2. 源碼下載

jpeg轉換為yuv格式圖像源碼

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