Kaltura Live Stream Requirements Guide

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A good source stream is essential for live streaming to work properly. Please configure your encoder according to the following recommendations:

Encoding Guidelines:

  • Video codec: H.264, main profile
  • Video frames per second (FPS): based on your capture device capabilities. Recommended values are 25 and 30
  • Key frame interval: 2 seconds
  • Audio Codec: AAC or MP3 (AAC recommended)
  • Audio Sample Rate: 44100 or higher
  • Audio Bitrate: 96Kbps and up
  • Strict CBR encoding recommended for optimum Adaptive bit-rate performance

Obtaining RTMP Endpoint URLs and Stream Name

  • In addition to video encoding configuration, you will need to configure the RTMP endpoint URLs and stream name on your encoder. See the article RTMP Endpoints for Kaltura Live Streaming for information on how to obtain the RTMP endpoint URLs and stream name for you live entry.

Single Bitrate vs Multiple Bitrate Ingest

When streaming to Kaltura, you can send either a single bitrate (using cloud transcoding) or send multiple bitrate streams (using pass-through) directly from your encoder to your live entry RTMP endpoint. In both ways you'll be able to serve ABR (adaptive bitrate) streams to your users.

Using a pass-through method is the most economical way if you have sufficient bandwidth and you have already invested in on-premises encoders.

Sending Single bitrate and Using Cloud Transcoding

An on-premises live encoder sends a single bitrate stream to the RTMP endpoint that is enabled to perform real-time cloud transcoding.

Guidelines

  • When possible, Kaltura recommends to send a single 720p stream with the following characteristics:
    • Video Codec: H.264
    • Resolution: 1280x720
    • FPS:  up to 30 frames-per-second
    • Audio: AAC
    • bitrate ~2Mbps 
  • Default cloud transcoding profiles are:
    • Source
    • 640x[auto] @ 964Kbps , H.264 main profile
    • 640x[auto] @ 664Kbps , H.264 baseline profile
    • 480x[auto] @ 464Kbps , H.264 baseline profile
  • HD and customized transcoding profiles are possible. Contact your Kaltura representative.

Sending Multi Bit-rate and Using Pass-through

An on-premises live encoder sends multi-bitrate to the RTMP endpoint that is configured for pass-through delivery. The ingested streams pass through without any further encoding.

Guidelines

  • Up to 3 flavors are enabled by default. Up to 6 pass-through flavors are supported. See Configuring Additionla Flavors for information on how to add additonal flavors.
  • The Key-frame MUST be aligned on all flavors.
  • Up to 15Mbps are aggregated for all flavors.

Configuring Additional Flavors

  • In your KMC, click on Settings→Transcoding Settings. A list of default transcoding profiles is displayed.
  • Click on "Switch to Advanced Mode" on the bottom left and then on "Switch to Live Profiles Mode". You should see your live transcoding profiles.
  • Click on "Passthrough" Transcoding to be able to add/remove pass-through flavors. 
  • Enable the flavors based on the number of flavors your local encoder will be broadcasting. For example:
    •  if you plan on broadcasting 4 flavors, enable "Source", "Ingest 2", "Ingest 3" and "Ingest 4"
    •  if you plan on broadcasting 5 flavors, enable "Source", "Ingest 2", "Ingest 3" ,"Ingest 4" and "Ingest 5"
    • and so on (up to 6 flavors)
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