The topic of video is very complex due to the many formats, codecs, containers and operating systems / browsers.
If a video is to be uploaded to OpenOlat, it is crucial to not only consider video format, but also file size (due to network traffic upon download), as network traffic generated by videos is generally quite high. A calculation example can be found here.
Videos are stored in so-called containers as a file with a file extension. The container contains one or more video and audio tracks, each encoded with a codec. A codec is essentially a compression algorithm and a description of how the data is stored.
Unfortunately, some file extensions are also used for container names and also encoding names. Therefore, when you look at a video name, it's never quite clear whether it's the encoding, the file extension, or the container.
The file size of a video depends on a number of parameters.
The following table shows the average bitrate as well as expected bitrates for other resolutions with conventional settings. Bitrates vary heavily depending on the type of video, resolution, codec and compression. These are merely benchmarks, and were calculated based on a MP4 file encoded with H.264.
Bitrate / Resolution
A movie with an average duration of 10 minutes and a 480x270 resolution therefore approximately requires about 53 MB memory. The same movie with a resolution of 720p HD though requires about 180 MB.
If you have to create or provide videos for OpenOlat yourself, a special transcoding software can help you transform files into the correct file format or the desired resolution. We recommend HandBrake, a free and open source software. More information on HandBrake can be found on the wikipedia HandBrake page as well as their commercial site https://handbrake.fr/.
1. Open HandBrake, and select the file to be converted. Starting formats are e.g. M4V or MOV files.
2. Under "Presets" select a general profile ("Very Fast" or "Fast" would be recommended), and check the "Web optimized" checkbox.
It would be best to leave the preset parameters untouched.
3. Select the desired size / resolution by opening the "Settings" under "Preview".