Re: [Linux-uvc-devel] Fusion Resolution

[Luc S. <lu...@sa...>]

> Maybe try this one, I have set in luvcview to resize the gui part . In 
> luvcview i only resize the xaxis as y is a constant, this one may resize the 
> two axis.

Thanks for the tip, i've used your method, but didn't give good result when
converting YUYV to YUV420P with resize in one pass. So i keep the idea to
keep the last known good value, but discarding it sometimes. I'll add this
algorithm in ekiga to convert palete (firewire UYVY and YUYV) without using a
temp buffer.
I've test this algo with a 1280x960 image to 320x240, 512x384, 640x480, 960x720.

#define FIX_FLOAT       12

    unsigned int dx = (in->width<<FIX_FLOAT)/out->width;
    unsigned int dy = (in->height<<FIX_FLOAT)/out->height;
    unsigned int fy, fx;

    for (fy=0, h=0; h<out->height; h+=2, fy+=dy*2)
      {
        /* Copy the first line with U&V */
        unsigned int yy = fy>>FIX_FLOAT;
        unsigned int yy2 = (fy+dy)>>FIX_FLOAT;
        const unsigned char *line1, *line2;
        unsigned char lastU, lastV;

        line1 = in->data[0] + (yy*2*in->width);
        line2 = in->data[0] + (yy2*2*in->width);
        lastU = line1[1];
        lastV = line1[3];
        for (fx=0, x=0; x<out->width; x+=2, fx+=dx*2)
         {
              unsigned int xx = (fx>>FIX_FLOAT)*2;
              *y++ = line1[xx];
              if ( (xx&2) == 0)
               {
                 *u++ = lastU = (line1[xx+1] + line2[xx+1])/2;
                 *v++ = lastV = (line1[xx+3] + line2[xx+3])/2;
               }
              else
               {
                 *u++ = lastU;
                 *v++ = lastV = (line1[xx+1] + line2[xx+1])/2;
               }
              xx = ((fx+dx)>>FIX_FLOAT)*2;
              *y++ = line1[xx];
              if ( (xx&2) == 0)
                 lastU = (line1[xx+1] + line2[xx+1])/2;
              else
                 lastV = (line1[xx+1] + line2[xx+1])/2;
         }
        /* Copy the second line without U&V */
        for (fx=0, x=0; x<out->width; x++, fx+=dx)
         {
           unsigned int xx = (fx>>FIX_FLOAT)*2;
           *y++ = line2[xx];
         }
      }