Kaltura MediaSpace - Recommended practices, video source formats and specifications (UW-Madison)

This document provides some recommended practices for creating and uploading media to Kaltura MediaSpace and outlines settings to use when producing audio and video files for upload to ensure successful processing.

Recommendations for creating and uploading media to Kaltura MediaSpace to help lighten the load on the system

These recommendations are more important while Kaltura MediaSpace is seeing unprecedented usage during the COVID-19 situation:

  • Upload a short (<5 second) sample video first so you know what to expect from the recording and upload process.
  • Break up your course content into 4-6 minute mini-lecture segments. Shorter videos keep your students attention and are faster to upload and process. See the Video Guidelines article for more info on recommended duration.
  • Upload material in the order you need it and upload early to allow time for file upload, processing, and potential errors.
    • Even when Kaltura MediaSpace is running smoothly other internet service providers are seeing degraded service which could limit your upload speed. Test your speed by going to fast.com, run the test and click the "Show more info" button to see your upload speed. 1 Mbps upload speed should be able to upload a 250 MB file in about 33 minutes.
  • Don’t upload all your course content at once. Space it out over a few days if possible.
  • If you are creating narrated slide lectures use Powerpoint for Office 365 slideshow (Win, Mac). If you use Kaltura Capture only record one input - webcam or screen. Recording both inputs doubles the file size, the time it takes to upload and process your file. Consider recording a short intro video with your webcam and the rest of your lecture segments with just the screen.
  • Upload and processing times will lengthen when there are a lot of users uploading content (for example late March 2020 during the COVID-19 situation). It may take a half-hour to an hour to upload a 15 minute video and process overnight. Keep an eye on the Learn@UW-Madison KnowledgeBase for notifications regarding performance impacts and outages.

While Kaltura supports a wide range of video formats and codecs, there are some recommended specifications for creating source files. These settings will ensure that your source file is quickly processed, while offering the optimal video and audio quality. The lists and tables below are designed to supply you with the recommended settings you should use when compressing a video project in software as Adobe Premiere, iMovie, and others. More detailed settings can be found in Kaltura's document Recommended Video Source Formats and Specifications.

Recommended video settings

  • Source Format/Container: MP4
  • Video Codec: H.264
  • Frame Size: As big as the largest frame size - generally we recommend a 1280 x 720 frame size
  • Bitrate: 3,750-5,000 Kbps bitrate
    See Frame Size with Recommended Bitrates for other frame sizes and data rates.
  • Frame rate / frames per second / fps: Use original frame rate if possible. Common frame rates include 24, 25, 29.97, 30 fps
  • Size: We recommend keeping the MP4 video file size below 2.0 GB.
  • Audio: AAC or MP3
Uploading videos with specifications outside of these recommendations may result in extended upload or processing times, and/or errors from Kaltura MediaSpace. Some editing and transcoding software allow you to set various export settings. In the options choose the following if available:
  • MP4 Streaming - choose Fast-Start.
  • MP4 Video Compression - choose H.264 High profile.
  • Bitrate – based on video dimensions. See table below.
  • Progressive scan mode – avoid interlaced video.
  • Multi pass –multi-pass will provide better quality. 
  • VBR vs. CBR - VBR (variable bitrate) usually provides better quality than CBR (constant bitrate).
  • Frame Rate – choose Current.

 Frame sizes with recommended bitrates

 16:9  4:3  Bitrate Range
 640 x 360  640 x 480  1,350-1,800 Kbps
 1280 x 720 (720p)    3,750-5,000 Kbps
 1920 x 1080 (1080p)    6,000-8,000 Kbps

Learn@UW-Madison generally recommends a maximum frame size of 1280 x 720. If you require your audience to discern especially fine detail in the video, then a 1920 x 1080 (1080p) frame size may be warranted.

Recommended audio settings

   Recommended  Avoid
 Compression  AAC, MP3  Nellymoser
 Channels  Stereo, Mono  Surround - 5.1, 7.1
 Sample Size  44.1 kHz or lower  
 Sound Levels  Normalized  Peaks, low sound

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