ffmpeg One-Liners August 29, 2015

One of the beauties of a *nix (Linux/Unix/OS X) shell is the power of wildcards. Combined with powerful tools such as ffmpeg, one can convert entire folders of audio files to the same format or select video files of a certain size. Below are some one-liners that I have used.


Slowing Down Video with FFmpeg July 26, 2015

GoPro cameras can record at high framerates (though lower resolutions). However, simple/free video editors are often incapable of slowing down or managing high framerate video. To deal with these clips, I use ffmpeg, an open source, cross platform, command line tool that can convert to and from every video format you will ever encounter. The basic command is ffmpeg -i <input> -filter:v "setpts:4.0*PTS" -r 30 <output>, where <input> and <output> are the input and output files. 4.0 slows the video down by a factor of four, appropriate for 120fps video. 30 refers to the output framerate. (Without this flag, the video would output 120fps, but the output would look the same because every frame would be repeated four times.) This command does not affect the audio. There are other parameters that can adjust the sound, but I have not needed to deal with it.

Projecting on a Cyclorama May 01, 2015

As the audience walks in, the orchestra is seated on the stage. On a huge screen along the back wall is a beautiful, Disney-themed logo. While the logo could easily stand alone on the cyclorama (a large screen behind a stage), we used the screen and a standard classroom projector to display various images and videos on the screen during the concert.

A while ago I briefly mentioned the Disney logo a friend of mine created for the Steinbrenner Orchestra. We started and ended the concert with this on the screen, but I did not explain how we switched between images during the show. The effect added a lot and the audience seemed to like it.

The projection was not an overly complicated addition to the show, but the effect it created was well worth the effort.

Note: This article is based on the Steinbrenner High School Orchestra‚Äôs Disney-themed spring concert in May 2014. I started writing this article a whopping ten months ago, and recently using a similar technique for a similar effect was motivated to finish writing this.


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