Video: Edge Compute and the CDN

Requests to servers are returned only tens of milliseconds later which is hardly any time to wait. But they quickly add up to users waiting seconds for their player to find out what video it wants, get it and finally start showing it. We all know that time is money when it comes to people ‘pressing play’ so reducing this startup time.

Anime streaming service, CrunchyRoll went to task to reduce their startup time. Michael Dale, VP of Engineering there, sits with Heather Chamberlin Mellish from AWS to describe how they used AWS to optimise the communications needed to establish a streaming session,

Named Katana, the project looked at the 12+ requests involved between third parties and the player itself which were all needed to start the session. Advertising companies need to be consulted, streaming manifest files need to represent chunks from multiple CDNs, SSAI and metrics were done with third-party vendors and the service is protected with DRM. These are just some of the factors which led to so many return trips needing to be accomplished before shipping.

This talk provides an overview and a little bit of a ‘behind the scenes’ of a blog post which also covers this project.

Key to success was deploying on AWS [email protected] which is a server which allows you to run code within AWS’s CloudFront. If you have Python or Javascript, this allows you to run it at the edge server closest to the user. For Crunchyroll’s global audience, this is particularly useful as it avoids having to set up infrastructure in every one of the AWS regions but still reduces much of the return trip time. Michael explains that, although Lambda is often viewed as an ephemeral service, when it’s not in use it can be suspended and used again in the future allowing it to maintain state for a player.

Michael explains the ways in which Katana has achieved success. Many of the third-party services have been brought into [email protected] and AWS. DRM and Advertising are still third-party, but doing most things within the edge and also pre-emptively returning information such as manifests has removed many requests. The video breaks down their use of GraphQL and how Multi-CDN and SSAI workflows have been implemented.

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Michael Dale Michael Dale
VP Engineering,
Heather Mellish Heather Chamberlin Mellish
Principal Edge Go To Market Specialist,
AWS Amazon Web Services

Video: Layer 4 in the CDN

Caching is a critical element of the streaming video delivery infrastructure, but with the proliferation of streaming services, managing caching is complex and problematic. Open Caching is an initiative by the Streaming Video Alliance to bring this under control allowing ISPs and service providers a standard way to operate.

By caching objects as close to the viewer as possible, you can reduce round-trip times which helps reduce latency and can improve playback but, more importantly, moving the point at which content is distributed closer to the customer allows you to reduce your bandwidth costs, and create a more efficient delivery chain.

This video sees Disney Streaming Services, ViaSat and Stackpath discussing Open Caching with Jason Thibeault, Executive Director of the Streaming Video Alliance. Eric Klein from Disney explains that one driver for Open Caching is from content producers which find it hard to scale, to deliver content in a consistent manner across many different networks. Standardising the interfaces will help remove this barrier of scale. Alongside a drive from content producers, are the needs of the network operators who are interested in moving caching on to their network which reduces the back and forth traffic and can help cope with peaks.

Dan Newman from Viasat builds on these points looking at the edge storage project. This is a project to move caching to the edge of the networks which is an extension of the original open caching concept. The idea stretches to putting caching directly into the home. One use of this, he explains, can be used to cache UHD content which otherwise would be too big to be downloaded down lower bandwidth links.

Josh Chesarek from StackPath says that their interest in being involved in the Open Caching initiative is to get consistency and interoperability between CDNs. The Open Caching group is looking at creating these standard APIs for capacity, configuration etc. Also, Eric underlines the interest in interoperability by the close work they are doing with the IETF to find better standards on which to base their work.

Looking at the test results, the average bitrate increases by 10% when using open caching, but also a 20-40% improvement in connection use rebuffer ratio which shows viewers are seeing an improved experience. Viasat have used multicast ABR plus open caching. This shows there’s certainly promise behind the work that’s ongoing. The panel finishes by looking towards what’s next in terms of the project and CDN optimisation.

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Eric Klein Eric Klein
Director, CDN Technology,
Dan Newman Dan Newman
Product Manager,
Josh Chesarek Josh Chesarek
VP, Sales Engineering & Support
Jason Thibeault Jason Thibeault
Executive Director, Streaming Video Alliance

Video: Mitigating Online Video Delivery Latency

Real-world solutions to real-world streaming latency in this panel from the Content Delivery Summit at Streaming Media East. With everyone chasing reductions in latency, many with the goal of matching traditional broadcast latencies, there are a heap of tricks and techniques at each stage of the distribution chain to get things done quicker.

The panel starts by surveying the way these companies are already serving video. Comcast, for example, are reducing latency by extending their network to edge CDNs. Anevia identified encoding as latency-introducer number 1 with packaging at number 2.

Bitmovin’s Igor Oreper talks about Periscope’s work with low-latency HLS (LHLS) explaining how Bitmovin deployed their player with Twitter and worked closely with them to ensure LHLS worked seamlessly. Periscope’s LHLS is documented in this blog post.

The panel shares techniques for avoiding latency such as keeping ABR ladders small to ensure CDNs cache all the segments. Damien from Anevia points out that low latency can quickly become pointless if you end up with a low-latency stream arriving on an iPhone before Android; relative latency is really important and can be more so than absolute latency.

The importance of HTTP and the version is next up for discussion. HTTP 1.1 is still widely used but there’s increasing interest in HTTP 2 and QUIC which both handle connections better and reduce overheads thus reducing latency, though often only slightly.

The panel finishes with a Q&A after discussing how to operate in multi-CDN environments.

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Damien Lucas Damien Lucas
CTO & Co-Founder,
Ryan Durfey Ryan Durfey
CDN Senior Product Manager,
Comcast Technology Solutions
Igor Oreper Igor Oreper
Vice President, Solutions
Eric Klein Eric Klein
Director, Content Distribution,
Disney Streaming Services (was BAMTECH Media)
Dom Robinson Dom Robinson