Video: CMAF And The Future Of OTT

Why is CMAF still ‘the future’ of OTT? Published in 2018, CMAF’s been around for a while now so what are the challenges and hurdles holding up implementation? Are there reasons not to use it at all? CMAF is a way of encoding and packaging media which then can be sent using MPEG DASH and HLS, the latter being the path Disney+ has chosen, for instance.

This panel from Streaming Media West Connect, moderated by Jan Ozer, discusses CMAF use within Akami, Netflix, Disney+, and Hulu. Peter Chave from Akamai starts off making the point that CMAF is important to CDNs because if companies are able to use just one CMAF file as the source for different delivery formats, this reduces storage costs for consumers and makes each individual file more popular thus increasing the chance of having a file available in the CDN (particularly at the edge) and reducing cache misses. They’ve had to do some work to ensure that CMAF is carried throughout the CDN efficiently and ensuring the manifests are correctly checked.

Disney+, explains Bill Zurat, is 100% HLS CMAF. Benefiting from the long experience of the Disney Streaming Services teams (formerly BAMTECH), but also from setting up a new service, Disney were able to bring in CMAF from the start. There are issues ensuring end-device support, but as part of the launch, a number were sunsetted which didn’t have the requirements necessary to support either the protocol or the DRM needed.

Hulu is an aggregator so they have strong motivation to normalise inputs, we hear from Hulu’s Nick Brookins. But they also originate programming along with live streaming so CMAF has an important to play on the way in and the way out. Hulu dynamically regenerates their manifests so can iterate as they roll out easily. They are currently part the way through the rollout and will achieve full CMAF compatibility within the next 18 months.

The conversation turns to DRM. CMAF supports two methods of DRM known as CTR (adopted by Apple) and CBC (also known as CBCS) which has been adopted by others. AV1 supports both, but the recommendation has been to use CBC which appears have been universally followed to date explains Netflix’s Cyril Concolato. Netflix have been using AV1 since it was finalised and are aiming to have most titles transitioned by 2021 to CMAF.

Peter comments from Akamai’s position that they see a number of customers who, like Disney+ and Peacock, have been able to enter the market recently and move straight into CMAF, but there is a whole continuum of companies who are restricted by their workflows and viewer’s devices in moving to CMAF.

Low latency streaming is one topic which invigorates minds and debates for many in the industry. Netflix, being purely video on demand, they are not interested in low-latency streaming. However, Hulu is as is Disney Streaming Services, but Bill cautions us on rushing to the bottom in terms of latency. Quality of experience is improved with extra latency both in terms of reduced rebuffering and, in some cases, picture quality. Much of Disney Streaming Services’ output needs to match cable, rather than meeting over-the-air latencies or less.

The panel session finishes with a quick-fire round of questions from Jan and the audience covering codec strategy, whether their workflows have changed to incorporate CMAF, just-in-time vs static packaging, and what customers get out of CMAF.

Watch now!
Speakers

Cyril Concolato Cyril Concolato
Senior Software Engineer,
Netflix
Peter Chave Peter Chave
Principal Architect,
Akamai
Nick Brookins Nick Brookins
VP, Platform Services Group,
Hulu
Bill Zurat Bill Zurat
VP, Core Technology
Disney Streaming Services
Jan Ozer Moderator: Jan Ozer
Contributing Editor, Streaming Media
Owner, StreamingLearningCenter.com

Video: Demystifying Video Delivery Protocols

Let’s face it, there are a lot of streaming protocols out there both for contribution and distribution. Internet ingest in RTMP is being displaced by RIST and SRT, whilst low-latency players such as CMAF and LL-HLS are vying for position as they try to oust HLS and DASH in existing services streaming to the viewer.

This panel, hosted by Jason Thibeault from the Streaming Video Alliance, talks about all these protocols and attempts to put each in context, both in the broadcast chain and in terms of its features. Two of the main contribution technologies are RIST and SRT which are both UDP-based protocols which implement a method of recovering lost packets whereby packets which are lost are re-requested from the sender. This results in a very high resilience to packet loss – ideal for internet deployments.

First, we hear about SRT from Maxim Sharabayko. He lists some of the 350 members of the SRT Alliance, a group of companies who are delivering SRT in their products and collaborating to ensure interoperability. Maxim explains that, based on the UDT protocol, it’s able to do live streaming for contribution as well as optimised file transfer. He also explains that it’s free for commercial use and can be found on github. SRT has been featured a number of times on The Broadcast Knowledge. For a deeper dive into SRT, have a look at videos such as this one, or the ones under the SRT tag.

Next Kieran Kunhya explains that RIST was a response to an industry request to have a vendor-neutral protocol for reliable delivery over the internet or other dedicated links. Not only does vendor-neutrality help remove reticence for users or vendors to adopt the technology, but interoperability is also a key benefit. Kieran calls out hitless switching across multiple ISPs and cellular. bonding as important features of RIST. For a summary of all of RIST’s features, read this article. For videos with a deeper dive, have a look at the RIST tag here on The Broadcast Knowledge.

Demystifying Video Delivery Protocols from Streaming Video Alliance on Vimeo.

Barry Owen represents WebRTC in this webinar, though Wowza deal with many protocols in their products. WebRTC’s big advantage is sub-second delivery which is not possible with either CMAF or LL-HLS. Whilst it’s heavily used for video conferencing, for which it was invented, there are a number of companies in the streaming space using this for delivery to the user because of it’s almost instantaneous delivery speed. Whilst a perfect rendition of the video isn’t guaranteed, unlike CMAF and LL-HLS, for auctions, gambling and interactive services, latency is always king. For contribution, Barry explains, the flexibility of being able to contribute from a browser can be enough to make this a compelling technology although it does bring with it quality/profile/codec restrictions.

Josh Pressnell and Ali C Begen talk about the protocols which are for delivery to the user. Josh explains how smoothstreaming has excited to leave the ground to DASH, CMAF and HLS. They discuss the lack of a true CENC – Common Encryption – mechanism leading to duplication of assets. Similarly, the discussion moves to the fact that many streaming services have to have duplicate assets due to target device support.

Looking ahead, the panel is buoyed by the promise of QUIC. There is concern that QUIC, the Google-invented protocol for HTTP delivery over UDP, is both under standardisation proceedings in the IETF and is also being modified by Google separately and at the same time. But the prospect of a UDP-style mode and the higher efficiency seems to instil hope across all the participants of the panel.

Watch now to hear all the details!
Speakers

Ali C. Begen Ali C. Begen
Technical Consultant, Comcast
Kieran Kunhya Kieran Kunhya
Founder & CEO, Open Broadcast Systems
Director, RIST Forum
Barry Owen Barry Owen
VP, Solutions Engineering
Wowza Media Systems
Joshua Pressnell Josh Pressnell
CTO,
Penthera Technologies
Maxim Sharabayko Maxim Sharabayko
Senior Software Developer,
Haivision
Jason Thibeault Moderator: Jason Thibeault
Executive Director,
Streaming Video Alliance

Video: HLS and DASH Multi-Codec Encoding & Packaging

As we saw yesterday, there’s an increasingly buoyant market for video codecs and whilst this is a breath of fresh air after AVC’s multi-decade dominance, we will likely never again see a market which isn’t fragmented with several dominant players, say AV1, AVC, VVC and VP9, each sharing 85% market share relatively equally and then ‘the rest’ bringing up the rear. So multi-codec distribution to home viewers is going to have to deal with delivering different codecs to different people.

fuboTV do this today and Nick Krzemienski is here to tell us how. Starting with an overview of fuboTV primarily streams both live and on VOD. Nick shows us the workflow they use and then explains how their AVC & HEVC combined workflow is set up. Starting with the ideal case where a single fmp4 is encoded into both AVD and HEVC, he proposes you would simply package both into an HLS and DASH manifest and let players work out the rest. Depending on your players, you may have to split out your manifests into single-codec files.

DRM’s very important for a sports broadcaster so Nick looks at how this might be achieved. CMAF allows you to deliver m3u8 and mpd files using CENC (Common ENCryption). This promises a single DRM process ahead of packaging, but the reality, we hear from Nick, is that you’ll need two sets of media for HLS and DASH if you’re going to use CENC.

When you’re delivering multiple manifest and, hence, multiple sources, how do you manage this? Nick outlines, and shows the code, of how he achieves this at the edge. Using Lamda, he’s able to look at the incoming requests and existing files at the CDN to deliver the right asset with the logic done close to the viewer. Nick closes by with his thoughts on the future for streaming and answering questions from the audience.

Watch now!
Download the presentation
Speakers

Nick Krzemienski Nick Krzemienski
Engineering Lead, VOD Encoding & Operations, fuboTV
Maintainer & Editor, awesome.video
Dom Robinson Host: Dom Robinson
Director and Creative Firestarter, id3as
Contributing Editor, StreamingMedia.com, UK

Video: DASH: from on-demand to large scale live for premium services

A bumper video here with 7 short talks from VideoLAN, Will Law and Hulu among others, all exploring the state of MPEG DASH today, the latest developments and the hot topics such as low latency, ad insertion, bandwidth prediction and one red-letter feature of DASH – multi-DRM.

The first 10 minutes sets the scene introducing the DASH Industry Forum (DASH IF) and explaining who takes part and what it does. Thomas Stockhammer, who is chair of the Interoperability Working Group explains that DASH IF is made of companies, headline members including Google, Ericsson, Comcast and Thomas’ employer Qualcomm who are working to promote the adoption of MPEG-DASH by working to improve the specification, advise on how to put it into practice in real life, promote interoperability, and being a liaison point for other standards bodies. The remaining talks in this video exemplify the work which is being done by the group to push the technology forward.

Meeting Live Broadcast Requirements – the latest on DASH low latency!
Akamai’s Will Law takes to the mic next to look at the continuing push to make low-latency streaming available as a mainstream option for services to use. Will Law has spoken about about low latency at Demuxed 2019 when he discussed the three main file-based to deliver low latency DASH, LHLS and LL-HLS as well as his famous ‘Chunky Monkey’ talk where he explains how CMAF, an implementation of MPEG-DASH, works in light-hearted detail.

In today’s talk, Will sets out what ‘low latency’ is and revises how CMAF allows latencies of below 10 seconds to be achieved. A lot of people focus on the duration of the chunks in reducing latency and while it’s true that it’s hard to get low latency with 10-second chunk sizes, Will puts much more emphasis on the player buffer rather than the chunk size themselves in producing a low-latency stream. This is because even when you have very small chunk sizes, choosing when to start playing (immediately or waiting for the next chunk) can be an important part of keeping the latency down between live and your playback position. A common technique to manage that latency is to slightly increase and decrease playback speed in order to manage the gap without, hopefully, without the viewer noticing.

Chunk-based streaming protocols like HLS make Adaptive Bitrate (ABR) relatively easy whereby the player monitors the download of each chunk. If the, say, 5-second chunk arrives within 0.25 seconds, it knows it could safely choose a higher-bitrate chunk next time. If, however, the chunk arrives in 4.8 seconds, it can choose to the next chunk to be lower-bitrate so as to receive the chunk with more headroom. With CMAF this is not easy to do since the segments all arrive in near real-time since the transferred files represent very small sections and are sent as soon as they are created. This problem is addressed in a later talk in this talk.

To finish off, Will talks about ‘Resync Elements’ which are a way of signalling mid-chunk IDRs. These help players find all the points which they can join a stream or switch bitrate which is important when some are not at the start of chunks. For live streams, these are noted in the manifest file which Will walks through on screen.

Ad Insertion in Live Content:Pre-, Mid- and Post-rolling
Whilst not always a hit with viewers, ads are important to many services in terms of generating the revenue needed to continue delivering content to viewers. In order to provide targeted ads, to ensure they are available and to ensure that there is a record of which ads were played when, the ad-serving infrastructure is complex. Hulu’s Zachary Cava walks us through the parts of the infrastructure that are defined within DASH such as exchanging information on ‘Ad Decision Parameters’ and ad metadata.

In chunked streams, ads are inserted at chunk boundaries. This presents challenges in terms of making sure that certain parameters are maintained during this swap which is given the general name of ‘Content Splice Conditioning.’ This conditioning can align the first segment aligned with the period start time, for example. Zachary lays out the three options provided for this splice conditioning before finishing his talk covering prepared content recommendations, ad metadata and tracking.

Bandwidth Prediction for Multi-bitrate Streaming at Low Latency
Next up is Comcast’s Ali C. Begen who follows on from Will Law’s talk to cover bandwidth prediction when operating at low-latency. As an example of the problem, let’s look at HTTP/1.1 which allows us to download a file before it’s finished being written. This allows us to receive a 10-second chunk as it’s being written which means we’ll receive it at the same rate the live video is being encoded. As a consequence, the time each chunk takes to arrive will be the same as the real-time chunk duration (in this example, 10 seconds.) When you are dealing with already-written chunks, your download time will be dependent on your bandwidth and therefore the time can be an indicator of whether your player should increase or decrease the bitrate of the stream it’s pulling. Getting back this indicator for low-latency streams is what Ali presents in this talk.

Based on this paper Ali co-authored with Christian Timmerer, he explains a way of looking at the idle time between consecutive chunks and using a sliding window to generate a bandwidth prediction.

Implementing DASH low latency in FFmpeg
Open-source developer Jean-Baptiste Kempf who is well known for his work on VLC discusses his work writing an MPEG-DASH implementation for FFmpeg called the DASH-LL. He explains how it works and who to use it with examples. You can copy and paste the examples from the pdf of his talk.

Managing multi-DRM with DASH
The final talk, ahead of Q&A is from NAGRA discussing the use of DRM within MPEG-DASH. MPEG-DASH uses Common Encryption (CENC) which allows the DASH protocol to use more than one DRM scheme and is typically seen to allow the use of ‘FairPlay’, ‘Widevine’ and ‘PlayReady’ encryption schemes on a single stream dependent on the OS of the receiver. There is complexity in having a single server which can talk to and negotiate signing licences with multiple DRM services which is the difficulty that Lauren Piron discusses in this final talk before the Q&A led by Ericsson’s VP of international standards, Per Fröjdh.

Watch now!
Speakers

Thomas Stockhammer Thomas Stockhammer
Director of Technical Standards,
Qualcomm
Will Law Will Law
Chief Architect,
Akamai
Zachary Cava Zachary Cava
Software Architect,
Hulu
Ali C. Begen Ali C. Begen
Technical Consultant, Video Architecture, Strategy and Technology group,
Comcast
Jean-Baptiste Kempf Jean-Baptiste Kempf
President & Lead VLC Developer
VideoLAN
Laurent Piron Laurent Piron
Principal Solution Architect
NAGRA
Per Fröjdh Moderator: Per Fröjdh
VP International Standards,
Ericsson