To configure video delivery using Low Latency MPEG-DASH, contact the technical support support@gcorelabs.com
The workings of Low Latency MPEG-DASH
What is the stream latency
The stream latency is the time interval between the moment the frame is captured and is displayed on the viewers' screens.
The usual latency of the video stream is 30-40 seconds.
Stream latency reasons
The video stream in the process of delivery to the end-user goes through several stages:
- Encoding/packaging: content processing to create stream segments.
- Transfer: upload to a CDN and deliver to the user's playback device.
- Players: segments loading and buffering them.
Each video stream conversion stage increases the video delay time, which can be critical for certain types of content: sports events, news releases, events related to esports, and interactive.
Low Latency MPEG-DASH
MPEG-DASH (from MPEG and Dynamic Adaptive Streaming over HTTP) is an adaptive data streaming technology for delivering streaming media content over the Internet via the HTTP protocol.
CMAF (Common Media Application Format) is a tool that allows reducing the size of the chunks.
Low Latency MPEG-DASH is a low-latency video delivery technology due to the use of the MPEG-DASH protocol and CMAF technology.
The live video delivery latency reduces to 4-5 seconds using this method
The workings of Low Latency MPEG-DASH
The LL-DASH mechanism uses an extension of the CMAF - CMAF-CTE (Chunked Transfer Encoding) technology.
A standard method of video delivery is when the encoder sends the segment to the CDN after its complete creation and as soon as the CDN receives the full segment, it passes it to the player.
With this approach, the video latency mainly depends on the length of the segments.
For example, if the segment length is 7 seconds when requesting and processing the first segment, the player displays a frame that is already 7 seconds late compared to the actual time.
Using CMAF-CTE, LL-DASH segments are divided into chunks — smaller non-overlapping and independent of one another segments of 2-4 seconds.
The independence of chunks allows the encoder not to wait for the end of the full loading of the segment, but to send it to the CDN and to the player in ready-made small fragments.
This approach helps to eliminate the segment duration factor that in standard video delivery method affects the video delay.
This means that for a segment with a length of 10 seconds and a segment with a length of 2 seconds, the latency will be the same.
The total latency between the content delivery server and the end viewers is no more than 4 seconds.
To use the Low Latency MPEG-DASH technology, it is necessary that CMAF is supported at all stages of video transmission, so we recommend using a player that supports the dash.js library.
Use your own or the G-Core Labs player.
Important! There is no dash.js support on iOS devices, so for our player, we use HLS fallback.
If you are going to use a different player, make sure that the necessary settings are made.
To check the Low latency, go to the demonstration page.
