create


ffmpeg: Create a video countdown

The code below was used to generate the video countdown timers that are available in the following playlist using ffmpeg:

#This example will create a 3 second video, with 100 frames per second and it will print the elapsed and remaining times using a two second accuracy.
fps=100;
seconds=3;
mantissaDigits=2;
upperFont=600;
lowerFont=100;
ffmpeg -loop 1 -i ~/Pictures/Black-Background.png -c:v libx264 -r $fps -t $seconds -pix_fmt yuv420p -vf "fps=$fps,drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf':fontcolor=yellow:fontsize=$upperFont:x=(w-text_w)/2:y=(h-text_h)/2:text='%{eif\:($seconds-t)\:d}.%{eif\:(mod($seconds-t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}',drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf':fontcolor=yellow:fontsize=$lowerFont:x=(w-text_w)/2:y=((h-text_h)/2)+$upperFont:text='Elapsed\: %{eif\:(t)\:d}.%{eif\:(mod(t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}'" "$seconds seconds countdown timer.mp4";

Notes:

  • We used a single black frame for the background that defined the size of the video frame as well.
  • Using the fps variable we defined the number of Frames per Second for the video.
  • The seconds variable defined the number of seconds the duration of the video should be.
  • The mantissaDigits variable defines how many decimal digits should be shown after the dot.
  • upperFont and lowerFont define the size of the fonts in the upper row and the lower one respectively.
  • We used the drawtext directive twice to write to the frames.

Notes on the first drawtext:

  • fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf' defines the font to be used for the text.
  • fontcolor=yellow defines the color of the font of the text.
  • fontsize=$upperFont defines the size of the font of the text.
  • x=(w-text_w)/2 defines the X-coordinate of the location for the text on the frame, here we center the text horizontally on the frame.
  • y=(h-text_h)/2 defines the Y-coordinate of the location for the text on the frame, here we center the text vertically on the frame.
  • text='%{eif\:($seconds-t)\:d}.%{eif\:(mod($seconds-t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}' We print the remaining seconds for the video to finish with specific decimal digit accuracy.

Notes on the second drawtext:

  • drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf' defines the font to be used for the text.
  • fontcolor=yellow defines the color of the font of the text.
  • fontsize=$lowerFont defines the size of the font of the text.
  • x=(w-text_w)/2 defines the X-coordinate of the location for the text on the frame, here we center the text horizontally on the frame.
  • y=((h-text_h)/2)+$upperFont defines the Y-coordinate of the location for the text on the frame, here shift the text from the vertical center  of the frame.
  • text='Elapsed\: %{eif\:(t)\:d}.%{eif\:(mod(t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}' We print the elapsed seconds since the video started with specific decimal digit accuracy.

Git: Create a branch on your local machine, switch to it and then push it on the server

Following are a couple of simple commands that we use daily to create a new branch on git and push it to the git server.

The following command will create locally a new branch called branch_name and switch to it.

git checkout -b branch_name;

The following command will push the local branch you are currently switched to on the git server.
It will be made available to the server using the name branch_name.

git push --set-upstream origin branch_name;

Using .tgz files 1

Create

To create a .tgz file, we used tar with the following parameters -czf:

  • -c or --create will create a new archive.
  • -z– or --gzip or --gunzip or --ungzip will filter the archive through gzip and compress it.
  • -f or --file=ARCHIVE will use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable TAPE. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default.

Example:

tar -czf $ARCHIVE_FILE_NAME.tgz $PATH_TO_COMPRESS;

Please note that the order of the parameters will not change the result.

Extract

To extract a .tgz or .tar.gz file using tar we used the following parameters -xzf:

  • -x or --extract --get will extract the files from the archive. Arguments are optional. When given, they specify names of the archive members to be extracted.
  • -z– or --gzip or --gunzip or --ungzip will filter the archive through gzip and decompress it.
  • -f or --file=ARCHIVE will use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable TAPE. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default.

Example:

tar -xzf $ARCHIVE_FILE_NAME.tgz;