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Version: 2.16

Dash Playback with CMAF

What Is CMAF (Common Media Application Format)?​

  • The Common Media Application Format (CMAF) is a standard designed to reduce HTTP delivery latency, typically to around 3-5 seconds. It aims to lower the cost, complexity, and latency of streaming. CMAF can be utilized with both DASH (Dynamic Adaptive Streaming over HTTP) and HLS (HTTP Live Streaming).

  • Ant Media Server fully supports LL-DASH (Low Latency DASH) through CMAF and LL-HLS (Low Latency HLS).

DASH Playback​

Dash playback is turned off by default, so you must enable it before playing a stream over the Dash protocol.

Enable DASH & CMAF Streaming​

Dash playback can be enabled from the application settings.

  • Navigate to your application (live or any other).
  • Go to Settings and under Dash & CMAF Streaming check Create DASH Streaming to enable it.

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Play CMAF (DASH) with Embedded Player​

You can use the embedded player play.html to play the streams with DASH.

  • Make sure that your stream is publishing on the server.

  • To play a stream with DASH, provide streamId as the id and dash as the playOrder parameter in the URL shown below.

    https://AMS-domain-name:5443/live/play.html?id=test&playOrder=dash

  • The dash playback will start automatically when the stream is live.

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Play MPEG-DASH stream directly via MPD​

Assume Dash muxing is enabled and a stream is published to the Ant Media Server.

The default MPEG-DASH (.mpd) URL will be as follows:

https://AMS-domain-name:5443/live/streams/streamId/streamId.mpd
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If you play the .mpd file directly, the stream latency will be native to MPEG-DASH, which is about 15 seconds.

More Details About Dash​

There are a few more options for CMAF and their default values. You can assume that the following values are in use if they are not specified in the properties file:

  • Duration of segments in MPD files.

    settings.dashSegDuration=6

  • Fragments are a property of fragmented MP4 files. Typically, a fragment consists of moof + mdat.

    settings.dashFragmentDuration=0.5

  • Target latency

    settings.dashTargetLatency=3.5

  • DASH window size. Number of files in the manifest

    settings.dashWindowSize=5

  • DASH extra window size. Number of segments kept outside of the manifest before being removed from the disk.

    settings.dashExtraWindowSize=5
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If you're using Dash streaming with ABR enabled, make sure the following property is enabled in your application's advanced settings:.


"forceAspectRatioInTranscoding": true,

The value is false by default. Check here for more information on this property.