ffmpeg从AVFrame取出yuv数据到保存到char*中

ffmpeg从AVFrame取出yuv数据到保存到char*中

 

很多人一直不知道怎么利用ffmpeg从AVFrame取出yuv数据到保存到char*中，下面代码将yuv420p和yuv422p的数据取出并保存到char*buf中。

其他格式可以自己去扩展，前提先看戏yuv的各种格式，yuv的各种格式链接：数据格式分析

 

先确保视频格式sws_getContext()转换后是YUV格式：

    out_buffer=(uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));//分配AVFrame所需内存
    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);//填充AVFrame

    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
            pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);

那么在后续的视频数据处理时，可以把YUV视频格式数据进行存储：

//如果是视频
else if (pstream_info[i].dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO)
{
    int new_videosize = pkt.size;
    int video_decode_size = avpicture_get_size(pstream_info->dec_ctx->pix_fmt, Zoom_Width,Zoom_Height);
    uint8_t * video_decode_buf =( uint8_t *)calloc(1,video_decode_size * 3 * sizeof(char)); //最大分配的空间，能满足yuv的各种格式

    // Decode video frame
    avcodec_decode_video2(pstream_info->dec_ctx, pDecodeFrame, &frameFinished,&pkt);
    if(frameFinished)
    {
        if (pstream_info->dec_ctx->pix_fmt == AV_PIX_FMT_YUV420P) //如果是yuv420p的
        {
            for(i = 0; i < pstream_info->dec_ctx->height; i++)
            {
                memcpy(video_decode_buf+pstream_info->dec_ctx->width*i,
                        pDecodeFrame->data[0]+pDecodeFrame->linesize[0]*i,
                        pstream_info->dec_ctx->width);
            }
            for(j = 0; j < pstream_info->dec_ctx->height/2; j++)
            {
                memcpy(video_decode_buf+pstream_info->dec_ctx->width*i+pstream_info->dec_ctx->width/2*j,
                        pDecodeFrame->data[1]+pDecodeFrame->linesize[1]*j,
                        pstream_info->dec_ctx->width/2);
            }
            for(k =0; k < pstream_info->dec_ctx->height/2; k++)
            {
                memcpy(video_decode_buf+pstream_info->dec_ctx->width*i+pstream_info->dec_ctx->width/2*j+pstream_info->dec_ctx->width/2*k,
                        pDecodeFrame->data[2]+pDecodeFrame->linesize[2]*k,
                        pstream_info->dec_ctx->width/2);
            }
        }
        else if (pstream_info->dec_ctx->pix_fmt == AV_PIX_FMT_YUV422P)//如果是yuv422p的
        {
            for(i = 0; i < pstream_info->dec_ctx->height; i++)
            {
                memcpy(video_decode_buf+pstream_info->dec_ctx->width*i,
                    pDecodeFrame->data[0]+pDecodeFrame->linesize[0]*i,
                    pstream_info->dec_ctx->width);
            }
            for(j = 0; j < pstream_info->dec_ctx->height; j++)
            {
                memcpy(video_decode_buf+pstream_info->dec_ctx->width*i+pstream_info->dec_ctx->width/2*j,
                    pDecodeFrame->data[1]+pDecodeFrame->linesize[1]*j,
                    pstream_info->dec_ctx->width/2);
            }
            for(k =0; k < pstream_info->dec_ctx->height; k++)
            {
                memcpy(video_decode_buf+pstream_info->dec_ctx->width*i+pstream_info->dec_ctx->width/2*j+pstream_info->dec_ctx->width/2*k,
                    pDecodeFrame->data[2]+pDecodeFrame->linesize[2]*k,
                    pstream_info->dec_ctx->width/2);
            }
        }
        else
        {
            //可扩展
        }
        video_decode_size = avpicture_get_size(pstream_info->dec_ctx->pix_fmt, pstream_info->dec_ctx->width,pstream_info->dec_ctx->height);
        new_videosize = video_decode_size;
        
        //缩放或格式转换
        if (pstream_info->dec_ctx->width != Zoom_Width ||
            pstream_info->dec_ctx->height != Zoom_Height ||
            pstream_info->dec_ctx->pix_fmt != Zoom_pix_fmt)
        {
            new_videosize = VideoScaleYuvZoom(Is_flip,pstream_info->dec_ctx->width ,pstream_info->dec_ctx->height,(int)pstream_info->dec_ctx->pix_fmt,
            Zoom_Width,Zoom_Height,Zoom_pix_fmt,video_decode_buf);
        }
        //这里可以取出数据
        frame_info->stream_idx = pstream_info->stream_idx;
        //frame_info->pts = pDecodeFrame->pkt_pts * 1000 * av_q2d(pstream_info->stream->time_base); //转化成毫秒
        frame_info->pts = pDecodeFrame->pkt_pts;
        frame_info->timebase_den = pstream_info->stream->time_base.den;
        frame_info->timebase_num = pstream_info->stream->time_base.num;
        frame_info->bufsize = new_videosize;
        memcpy(frame_info->buf,video_decode_buf,new_videosize);
    }
    else
    {
        //缓存
        frame_info->stream_idx = pstream_info->stream_idx;
        frame_info->pts = 0;
        frame_info->timebase_den = 0;
        frame_info->timebase_num = 0;
        frame_info->bufsize = 0;
        memset(frame_info->buf,0,MAX_FRAME_SIZE);
    }
    if (video_decode_buf)
    {
        free(video_decode_buf);
        video_decode_buf = NULL;
    }
    video_decode_size = 0;
}

也可以把YUV数据进行存储为PPM格式(Linux系统下的图片格式)：

//如果是视频
else if (pstream_info[i].dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO)
{
    // Decode video frame
    avcodec_decode_video2(pstream_info->dec_ctx, pDecodeFrame, &frameFinished,&pkt);
    if(frameFinished)
    {
        sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
        if((++k<=30) && (k%3==0)) {
            SaveFrame(pFrameYUV, pCodecCtx->width, pCodecCtx->height, k);
        }
    }
}

void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame)
{
    FILE *pFile;
    char szFilename[32];
    int  y;
    
    SDL_Log("%d * %d", width, height);
    // Open file
    sprintf(szFilename, "frame/frame%d.ppm", iFrame);
    pFile=fopen(szFilename, "wb");
    if(pFile==NULL)
    return;
    
    // Write header
    fprintf(pFile, "P6
%d %d
255
", width, height);
    
    // Write pixel data
    for(y=0; y<height; y++) {
        fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, width*3, pFile);
    }
    
    // Close file
    fclose(pFile);
}