ffmpeg解码的几种方法

方法1：

const AVCodec *codec;

AVCodecParserContext *parser;

AVCodecContext *c= NULL;
FILE *f;

codec = avcodec_find_decoder(AV_CODEC_ID_MPEG1VIDEO);

if (!codec) {

fprintf(stderr, "codec not found\n");

exit(1);

}

parser = av_parser_init(codec->id);

if (!parser) {

fprintf(stderr, "parser not found\n");

exit(1);

}

c = avcodec_alloc_context3(codec);

if (avcodec_open2(c, codec, NULL) < 0) {

fprintf(stderr, "could not open codec\n");

exit(1);

}

f = fopen(filename, "rb");

if (!f) {

fprintf(stderr, "could not open %s\n", filename);

exit(1);

}

while (!feof(f)) {

/* read raw data from the input file */

data_size = fread(inbuf, 1, INBUF_SIZE, f);

if (!data_size)

break;

/* use the parser to split the data into frames */

data = inbuf;

while (data_size > 0) {

ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,

data, data_size, AV_NOPTS_VALUE,AV_NOPTS_VALUE, 0);

if (ret < 0) {

fprintf(stderr, "Error while parsing\n");

exit(1);

}

data += ret;

data_size -= ret;

if (pkt->size)

decode(c, picture, pkt, outfilename);

}

}

/* flush the decoder */

decode(c, picture, NULL, outfilename);

方法2：

AVFormatContext *pFormatCtx;
    int             i, videoindex;
    AVCodecContext  *pCodecCtx;
    AVCodec         *pCodec;
    AVFrame *pFrame,*pFrameYUV;
    AVPacket *packet;
    struct SwsContext *img_convert_ctx;
    //SDL
    int ret, got_picture;
    int screen_w=0,screen_h=0;
    SDL_Surface *screen;
    SDL_Overlay *bmp;
    SDL_Rect rect;
    SDL_Thread *video_tid;
    SDL_Event event;

    char filepath[]="bigbuckbunny_480x272.h265";
    av_register_all();
    avformat_network_init();
    pFormatCtx = avformat_alloc_context();

    if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=0){
        printf("Couldn't open input stream.\n");
        return -1;
    }
    if(avformat_find_stream_info(pFormatCtx,NULL)<0){
        printf("Couldn't find stream information.\n");
        return -1;
    }
    videoindex=-1;
    for(i=0; i<pFormatCtx->nb_streams; i++)
        if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
            videoindex=i;
            break;
        }
    if(videoindex==-1){
        printf("Didn't find a video stream.\n");
        return -1;
    }
    pCodecCtx=pFormatCtx->streams[videoindex]->codec;
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
    if(pCodec==NULL)
    {
        printf("Codec not found.\n");
        return -1;
    }
    if(avcodec_open2(pCodecCtx, pCodec,NULL)<0)
    {
        printf("Could not open codec.\n");
        return -1;
    }

    pFrame=av_frame_alloc();
    pFrameYUV=av_frame_alloc();
    //uint8_t *out_buffer=(uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
    //avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
//------------SDL----------------
    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        printf( "Could not initialize SDL - %s\n", SDL_GetError());
        return -1;
    }


    screen_w = pCodecCtx->width;
    screen_h = pCodecCtx->height;
    screen = SDL_SetVideoMode(screen_w, screen_h, 0,0);

    if(!screen) {
        printf("SDL: could not set video mode - exiting:%s\n",SDL_GetError());
        return -1;
    }

    bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,SDL_YV12_OVERLAY, screen);

    rect.x = 0;
    rect.y = 0;
    rect.w = screen_w;
    rect.h = screen_h;

    packet=(AVPacket *)av_malloc(sizeof(AVPacket));

    printf("---------------File Information------------------\n");
    av_dump_format(pFormatCtx,0,filepath,0);
    printf("-------------------------------------------------\n");


    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
    //--------------
    video_tid = SDL_CreateThread(sfp_refresh_thread,NULL);
    //
    SDL_WM_SetCaption("Simple FFmpeg Player (SDL Update)",NULL);

    //Event Loop

    for (;;) {
        //Wait
        SDL_WaitEvent(&event);
        if(event.type==SFM_REFRESH_EVENT){
            //------------------------------
            if(av_read_frame(pFormatCtx, packet)>=0){
                if(packet->stream_index==videoindex){
                    ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
                    if(ret < 0){
                        printf("Decode Error.\n");
                        return -1;
                    }
                    if(got_picture){

                        SDL_LockYUVOverlay(bmp);
                        pFrameYUV->data[0]=bmp->pixels[0];
                        pFrameYUV->data[1]=bmp->pixels[2];
                        pFrameYUV->data[2]=bmp->pixels[1];
                        pFrameYUV->linesize[0]=bmp->pitches[0];
                        pFrameYUV->linesize[1]=bmp->pitches[2];
                        pFrameYUV->linesize[2]=bmp->pitches[1];
                        sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);

                        SDL_UnlockYUVOverlay(bmp);

                        SDL_DisplayYUVOverlay(bmp, &rect);

                    }
                }
                av_free_packet(packet);
            }else{
                //Exit Thread
                thread_exit=1;
                break;
            }

1.         }

    }

    SDL_Quit();

    sws_freeContext(img_convert_ctx);

    //--------------
    //av_free(out_buffer);
    av_free(pFrameYUV);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);