Monday, July 14, 2014

MPEG-DASH : Performance of Low Latency Live Streaming using DASH

HTTP Streaming is a recent topic in multimedia communications with on-going standardization activities, especially with the MPEG DASH standard which covers on demand and live services. One of the main issues in live services deployment is the reduction of the overall latency. Low or very low latency streaming is still a challenge.
HTTP Streaming is the new approach for streaming video over  the Internet, for live and on demand cases. However, current  approaches, in particular using DASH, are not deployed for low latency live services. In this paper, we proposed to use the amendment 1 of DASH in combination with Gradual 
Decoding Refresh encoding and to deliver media frames up to  the frame. We measured the overhead introduced by the GDR  encoding and the associated fragmentation. We showed that especially for high definition content, the overhead in the  order of 13% can be acceptable. We also described an 
implementation of a streaming system comprising a DASH  live encoder generator, a DASH-aware web server and a  DASH client. With this system, we validated the approach for  very low latency streaming in local networks, with latency as  low as 240 ms. In future work, we plan to examine how such  low latency system will behave in real content delivery  networks, and to further exploit the combined use of GDR and  chunk encoding to enable fetching segments not from their start, reducing the initial delay and enabling faster switching

In this Paper, Author push the use of DASH to its limits with regards to latency, down to fragments being only one frame, and evaluate the overhead introduced by that approach and the combination of: low latency video coding techniques, in particular Gradual Decoding Refresh; low latency HTTP streaming, in particular using chunked-transfer encoding; and associated ISOBMF packaging.

We experiment DASH streaming using these techniques in local networks to measure the actual end-to-end latency, as low as 240 milliseconds, for an encoding and packaging overhead in the order of 13% for HD sequences and thus validate the feasibility of very low latency DASH live streaming in local networks.


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