Abstract
During the past decade, broadcasting has been challenged by OTT services, offering a more personalized and flexible way of experiencing the content. The on-demand features paved the way for new media delivery paradigms, replacing traditional MPEG-TS stream-based approach by file-based IP protocols. With those new protocols came new ways of monetizing the content. While traditional TV leveraged advertisements to increase broadcasters' revenues for decades, it has never approached the level of personalization offered by OTT, until the release of ATSC-3.0 [8] and its IP stack in 2016. However, OTT services have some drawbacks compared to broadcasting: video quality, latency, and scaling capabilities when millions of viewers want to access a content at the same time. In this paper, we describe how the several recent technologies can be exploited to address these drawbacks. An end-to-end chain is also demonstrated, bringing significant improvement over existing approaches in terms of bandwidth, latency and experience.
The Versatile Video Coding (VVC) [1] standard has been released in mid-2020 by ISO/IEC MPEG and ITU-T VCEG. VVC has been designed to address a wide range of applications and video formats, while providing a substantial bandwidth saving (around 50%), compared to its predecessor, High Efficiency Video Coding (HEVC) [10], at an equivalent perceived video quality [12]. In this paper, VVC is used to reduce the bandwidth occupied by video over the network, which is a key issue in 2021, knowing that more than 80% of the internet traffic is used to deliver video content [2]. A live software implementation of VVC provided by ATEME is used in the headend before packaging and distribution, producing ISO/IEC Base Media File Format (ISOBMFF) output files [6].
The Common Media Application Format in its Low-Latency profile (CMAF-LL) is then used to deliver the video [7], leveraging HTTP chunk transfer encoding to deliver Low-Latency DASH (LL-DASH) [3]. To further reduce the bandwidth, the DASH-ROUTE server is leveraged to deliver multicast instead of redundant unicast sessions [11]. The ATEME packager, origin server and DASH-ROUTE multicast server are used for that purpose. Combined with VVC efficient source-coding, this paper provides a bandwidth efficient and low-latency manner of delivering OTT services at scale.
This paper adopts multi-period DASH manifests for ad insertion using XLink to signal ad-server URL. Typical streams coming from broadcasting studios, embedding SCTE-35 splicing event are used as input and interpreted by ATEME pre-processing engine to trigger the ad-insertion and multi-period events in the DASH manifest. The ad-server is then provisioned with VVC-encoded ad-clip for reducing the CDN cost of those files. To demonstrate such advanced features, the GPAC Framework [9] is used with real-time VVC software decoder [4, 5]. The multicast gateway and player from GPAC embeds the real-time decoder libraries to demonstrate both the ROUTE demuxing and ad-replacement within the player.
The benefits of using VVC and ROUTE has been measured. It is verified that the proposed solution enables similar latency as typical terrestrial broadcast services with a high-level of quality providing around 3 seconds glass-to-glass latency leveraging CMAF with HTTP chunk transfer encoding. An accurate description of encoding, packaging and delivery setting will be presented in the poster. Finally, the interoperability is demonstrated by integrating it with other CDN-providers and devices.
In summary, this paper describes implementation and demonstration of a state-of-the-art complete end-to-end and transmission chain for OTT, That aims to address well-known OTT drawbacks, such as latency and scaling capability, by combining the VVC, CMAF-LL and DASH-ROUTE. The proposed solution demonstrates significant benefits in terms of latency reduction, bandwidth saving and network traffic reduction, while enabling flexible and customized ad-insertion solutions for live OTT services. The interoperability of the proposed components is also demonstrated by integrating the chain with 3rd party CDN-providers and integrating it within broadcast environment. As a result, this paper shows the good degree of maturity of emerging technologies such as VVC, when combined with CMAF and ROUTE.
