Extend CMAF usage for large scale video delivery

During the last decade, an immense momentum drove HTTP adaptive streaming to become the key protocol for video streaming. This keen interest can be explained by the increasing bandwidth of internet connections and the tremendous progress of mobile networks with the emergence of LTE technologies. Moreover, using TCP based protocol is a grail for both developers and final users as it is supported by most of the connected devices and browsers, and it significantly reduces the handling of network related issues.

Among several protocols, the market has been dominated by two protocols: MPEG-DASH and HTTP live streaming. This situation presented a major drawback as content providers need to package the same content twice to ensure covering most of the users. The obvious solution was to unify the packaging and that is what happened with the advent of the playlist agnostic container format called 'Common Media Application Format' (CMAF) [4]. In addition to reducing the number of stored segments for OTT support, CMAF improved the versatility and the interoperability with modern technologies. It has also provided solutions to metadata carriage and to significantly reduce the OTT latency which used to be the bottleneck of the technology.

Things will not stop here for CMAF as recently, in March 2020, an ingest protocol based on CMAF was published by the CMAFIF and the DASH-IF and was revised during 2021 [2]. This protocol was initially aiming at defining a push-based communication between an encoder and a receiving entity such as a just-in-time packager or a Content Delivery Network, but it revealed to be a game changer to put CMAF everywhere. Indeed, today's first mile delivery uses mainly MPEG-2 TS and protocols like SRT or ZIXI for B2B headend and this way of encapsulation involves a loss of information as we need to go through specific sub-protocols to carry on meta data such as Advertising, thumbnails, and timed text over MPEG-2 TS. This loss can be avoided by using a complete content carriage with ISO BMFF [3]. Moreover, the ingest protocol allows going beyond the classic flow and make CMAF a robust communication support at large scale between any entities exchanging video streams. It can be a communication between encoders and transcoders or between encoders and storage entities or between a storage and a transcoder or even between a playout and a transcoder.

In this paper we present the CMAF ingest protocol and its key features. We also detail the benefits of using this technology compared to those of other existing formats in terms of redundancy, metadata carriage and support of recent codecs and timed text. Then, we present the evolution of CMAF thanks to the ingest protocol to handle video transmission at large scale in a fully standardized fashion. Finally, we will show concrete implementation architecture of communication between an encoder and a smart packager using timed text and timed metadata tracks for SCTE35 carriage [1, 5].