✎ codingtips [Nilgiri Voynich]

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====== Coding Tips ======

===== C =====
==== How to hide a temporary file ====
 This works because the filename and data are stored separately. The filename can be unlinked, and the data will only be released once the file stream is closed. <verbatim>
FILE *fd = fopen("hidden.file","w");
unlink("hidden.file");
fprintf(fd,"This is hidden information\n");
...
fclose(fd);
</verbatim>

===== ffmpeg =====
==== Create video from image ====
 <verbatim>
% ffmpeg -loop_input -i image.jpg -r 29.97 -t 10 -qscale 2 video.mpg
</verbatim> Where ''-t'' is the duration in seconds 
==== Combine audio and video ====
 <verbatim>
% ffmpeg -i sound.mp3 -i video.avi final.avi
</verbatim> 
==== Cut scene from dvr-ms file ====
 <verbatim>
% ffmpeg -y -ss 1250 -t 81 -i input.dvr-ms -vcodec copy -acodec copy -f dvd out.mpg
% ffmpeg -sameq -i out.mpg final.mp4
</verbatim> Where ''-ss'' is start time in seconds, ''-t'' is duration in seconds
==== Convert ''mkv'' to ''mpg'' file ====
<verbatim>
% ffmpeg -i input_video.mkv -target ntsc-dvd -acodec mp2 -ab 192 -ac 2 -ar 48000 -b 4096 -r 29.97 -s 720x480 -vcodec mpeg2video -y output_video.mpg
</verbatim>

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