[Ffmpeg-devel] vhook jpeg problem

[Vecais_Dumais_Laacis]

Hello ffmpeg-devel,

  i'm trying to fix this problem for 3 days and i cant get any
  further.

  1) i modified framehook and ffmpeg sources to pass additional data
  (AVFormatContext *is, AVInputStream *ist, - so i can know
  duration/framecount in hook)
  2) i modified null.c hook to save specific frames - 4 frames from
  whole video.
  3) i tried to save them as jpeg but as result i get pixelated image
  example: http://3priedez.net/files/pljek51.jpg
  image width and height is as should be
  4) converting to rgb24 and saving as ppm works correctly
  (ppm converted to jpeg to save traffic -
  http://3priedez.net/files/frame0.jpg )
  5) exporting code (mostly taken from jpeg.c and added some values to
  try to fix pixelate problem). also nothing changes if i use
  AVPicture pointer passed to hook.


int my_write_jpeg(AVInputStream *ist){
            char *buf=0;
            AVPicture picture1;
    char b[1024];
        FILE *fil;

    AVCodecContext *c;
    uint8_t *outbuf = NULL;
    int outbuf_size, ret, size, i;
    AVFrame *picture;                   
    ret = -1;
    c = avcodec_alloc_context();
    if (!c)
        return -1;
    picture = avcodec_alloc_frame();
    if (!picture)
        goto fail2;
    c->width = ist->st->codec->width;
    c->height = ist->st->codec->height;
    c->codec_id=CODEC_ID_MJPEG;

    c->pix_fmt=PIX_FMT_YUVJ420P;
    //as ffmpeg already outputs yuv420 image to hook we dont convert
    //anything here
        for(i=0;i<3;i++) {
                picture->data[i] = ist->st->codec->coded_frame->data[i];
                picture->linesize[i] = ist->st->codec->coded_frame->linesize[i];
        }

    picture->quality = 3;
    c->flags |= CODEC_FLAG_QSCALE;
    c->time_base.num=1;
    c->time_base.den=1;
    c->bit_rate=4000000;
    c->nsse_weight=0;

    if (avcodec_open(c, &mjpeg_encoder) < 0)
        goto fail1;
    c->bit_rate=4000000;
    c->nsse_weight=0;
    
    outbuf_size = 1000000;
    outbuf = av_malloc(outbuf_size);

    size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
    if (size < 0)
        goto fail;
    snprintf(b, 1024, "pljek%ld.jpg", pr);
    fil=fopen(b, "wb");
    if(fil){ 
        fwrite(outbuf, size, 1, fil);
        fclose(fil);
    }
    ret = 0;

 fail:
    avcodec_close(c);
    av_free(outbuf);
 fail1:
    av_free(picture);
 fail2:
    av_free(c);
    return ret;

}

what am i doing wrong?

-- 
Best regards,
 Vecais_Dumais_Laacis                          mailto:vdl at 3priedez.net