[Libav-user] get RGB values from ffmpeg frame

[Navin]

Been trying these techniques, but I keep getting crashes. Help please?:

         avpicture_fill((AVPicture*) frame2, frame2_buffer, 
PIX_FMT_RGB24, width2, height2);
         //printf("data = %d, %d, %d, %d 
\n",frame2->data[0],frame2->data[1],frame2->data[2],frame2->data[3]);
         //printf("linesize = %d %d %d\n",frame2->linesize[0], 
frame2->linesize[1], frame2->linesize[2]);
         //printf("width = %d\n", pCodecCtx->width);
         //printf("height = %d\n", pCodecCtx->height);
         //std::cin.get();

         int linesize = frame2->linesize[0];
         for(int xx = 0; xx < (linesize * width1)-1; xx += 3)
         {
             int r = frame2->data[0][xx];//int r = frame2->data[0][xx];
             int g = frame2->data[0][xx+1];
             int b = frame2->data[0][xx+2];
             printf("xx=%d                 r=%d, g=%d, b=%d \n",xx, r, 
g, b);
         }
         printf("frame%d done----------------",i++);
         //for(int xx = 0; xx < width1; xx = xx + 3)
         //{
         //    for(int yy = 0; yy < height1; ++yy)
         //    {
         //        //int p = xx*3 + yy*frame2->linesize[0];
         //        //int p = xx * 3 + yy * linesize;
         //        printf("yy=%d xx=%d",yy,xx);
         //        int p = yy * linesize + xx;
         //        printf("p=%d\n",p);
         //        int r = frame2->data[0][p];
         //        int g = frame2->data[0][p+1];
         //        int b = frame2->data[0][p+2];
         //        printf("[r=%d, g=%d, b=%d ]\n", r, g, b);
         //    }//for
         //}//for

Nav

On 11/20/2012 8:52 AM, Nav wrote:
> Hi! Glad to be part of this mailing list.
> What I wanted to create, was a program which would receive a streaming 
> video, and when it decodes a frame of the video into either a bitmap 
> format or just pure RGB (perhaps stored in a char array), it would 
> notify another program that it has received a frame, and the other 
> program would take the RGB values and display it.
> I've already asked this question here: 
> http://ffmpeg.zeranoe.com/forum/viewtopic.php?f=15&t=805
> and rogerdpack told me to post my question on the libav mailing list.
> I have been through many websites, but they either use img_convert 
> (which doesn't work) or sws_scale, which crashes when I try to use it 
> with RGB.
> Could anyone help with a complete piece of code which can give me the 
> RGB values of a frame?
>
> This is a part of the YUV conversion that I tried initially.
>
>   i=0;
>   while(av_read_frame(pFormatCtx, &packet) >= 0)
>   {
>     // Is this a packet from the video stream?
>     if(packet.stream_index==videoStream)
>     {
>     // Decode video frame
>     avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
>
>     // Did we get a video frame?
>     if(frameFinished)
>     {
>         // Convert the image into YUV format that SDL uses
>         sws_scale( sws_ctx, (uint8_t const * const *)pFrame->data, 
> pFrame->linesize, 0, pCodecCtx->height, pict.data, pict.linesize );
>
>