Transcoding. Transcoding to HLS and MPEG-DASH (CMAF) protocols

How HLS works
How Low Latency MPEG-DASH works

The streaming platform supports:

  • Receiving streams from your source (PULL) or a dedicated publication point (PUSH) using the following protocols: RTMP, RTSP, and SRT. The stream is transcoded to get streams of lower quality and sent with adaptive streaming via CDN in  HLS/MPEG-DASH (CMAF Low Latency) formats.   
  • Uploading videos in almost any format: from standard mp4 to 4k HDR. Video is transcoded to get videos of lower quality and sent with adaptive streaming via CDN in HLS format.

How HLS works 

HLS (HTTP Live Streaming) is an adaptive protocol based on HTTP. Apple developed it for streaming both recorded video and real-time video. Because HLS is based on the HTTP protocol, it is cached on CDN servers and distributed via CDN as static content.

The video stream is transferred via the HLS protocol using our Streaming Platform with CDN.

It is delivered from the origin server to the final viewer with up to 8–10 seconds delay.

This is faster than transmitting video via satellite or IPTV.

gcore_streaming_latency.png

HLS splits the stream into small fragments called chunks (Mpeg-ts format), information about which is stored in a particular file called manifest (m3u8 format).

An application, e.g., a browser, requests a manifest and sequentially plays the fragments it contains. 

Then it plays all the fragments and again requests the manifest and, if it contains new fragments, loads and sequentially plays them.

How Low Latency MPEG-DASH works 

MPEG-DASH (from MPEG and  Dynamic Adaptive Streaming over HTTP) is an adaptive streaming technology that can deliver multimedia over the Internet via the HTTP protocol.

This protocol is compatible with CMAF (Common Media Application Format), a tool that allows reducing the size of chunks.

LL-DASH segments are split into 2-4 seconds chunks.

It allows CDN-servers not to wait for the entire segment loading but to give it to the player in small fragments, reducing the delay.

The delay between the content delivery server and the end viewers is about 4 seconds.  

 

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