global variables in C

the "not bad" way to define global variables in C


#ifdef FOO_LIBRARY_C 
#define GLOBAL_PREFIX 
#else 
#define GLOBAL_PREFIX extern 
#endif 

GLOBAL_PREFIX int a,b,c

http://stackoverflow.com/questions/2868651/including-c-header-file-with-lots-of-global-variables

Video pixel formats

 http://www.fourcc.org/yuv.php

conversion HD uyvy -> RGB

                i=0;
                for (y=0;y<image.rows;y++)
                {
                    uchar* ptr_cv= (uchar *)( image.ptr() + image.channels()*y * image.cols);   
                    for (x=0;x<image.cols/2;x++)
                    {
                        U = pData[i]-128.0;
                        YY1 = 1.164*(pData[i+1]-16);
                        V = pData[i+2]-128.0;
                        YY2 = 1.164*(pData[i+3]-16);
                        i+=4;

                        B=YY1          + 1.793*U;
                        G=YY1 - 0.534*V- 0.213*U;
                        R=YY1 + 2.115*V;
                        if (R<0) R=0;if (G<0) G=0;if (B<0) B=0;
                        if (R>255) R=255;if (G>255) G=255;if (B>255) B=255;
                        j=2*image.channels()*x;
                        ptr_cv[j]  = (unsigned char)B;
                        ptr_cv[j+1]= (unsigned char)G;
                        ptr_cv[j+2]= (unsigned char)R;
                        B=YY2          + 1.793*U;
                        G=YY2 - 0.534*V- 0.213*U;
                        R=YY2 + 2.115*V;
                        if (R<0) R=0;if (G<0) G=0;if (B<0) B=0;
                        if (R>255) R=255;if (G>255) G=255;if (B>255) B=255;
                        ptr_cv[j+3]  = (unsigned char)B;
                        ptr_cv[j+4]= (unsigned char)G;
                        ptr_cv[j+5]= (unsigned char)R;

                    }
                }

Merging mp4 videos

 mencoder *.mp4 -oac copy -ovc copy ../all.mp4

Not satisfied with Unity on Ubuntu 12

With Unity  on Ubuntu 12, the user interface changed so much that you drastically need to change your habits. Is it worth spending time for what looks like a commercial move toward tablets? For my own work, I started to use Mint, whose look and feel is closer to Ubuntu 10.

enhance contrast of a series of images

for f in *jpg ; do convert -auto-level $f ../$f;  done

encodage DVD

 mencoder -oac mp3lame -lameopts mode=2:cbr:br=128:vol=0 -dvd-device /media/DVD_VIDEO dvd://0 -aid 128 -sid 1 -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1400:vhq:autoaspect -o toto.avi