codecs

Video: State of Compression: Versatile Video Coding – H.266/VVC

Posted on by Russell Trafford-Jones

An evolution from HEVC, VVC is a codec that not only delivers the traditional 50% bit rate reduction over its predecessor but also has specific optimisations for screen content (e.g. computer gaming) and 360-degree video.

Christian Feldmann from Bitmovin explains how VCC manages to deliver this bitrate reduction. Whilst VVC makes no claims to be a totally new codec, Christian explains that the fundamental way the codec works, at a basic level, is the same as all block-based codecs including MPEG 2 and AV1. The bitrate savings come from incremental improvements in technique or embracing a higher computation load to perform one function more thoroughly.

Block partitioning is one good example. Whilst AVC macroblocks are all 16×16 pixels in size, VVC allows 128×128 blocks. For larger areas of ‘solid’ colour, this allows for more efficiency. But the main advance comes in the fact you can sub-divide each of these blocks into different sized rectangles. Whilst sub-dividing has always been possible back to AVC, we have more possible shapes available now allowing the divisions to be created in closer alignment with the video.

Tiles and slices are a way of organising the macroblocks, allowing them to be treated together as a group. This is grouping isn’t taken lightly; each group can be decoded separately. This allows the video to be split into sub-videos. This can be used for multiviewer-style applications or, for instance, to allow multiple 4k decoders to decode a 16k. This could be one of those features which sees lots of innovative use…or, if it’s too complicated/restricted, will see no mainstream take-up.

Christian outlines other techniques such as intra-prediction where macroblocks are predicted from already-decoded macroblocks. Any time a codec can predict a value, this tends to reduce bitrate. Not because it necessarily gets it right, but because it then only needs an error correction, typically a smaller number, to give it the correct value. Similarly, prediction is also possible now between the Y, U and V channels.

Finishing off, Christian hits geometric partitioning, similar to AV1, which allows diagonal splitting of macroblocks with each section having separate motion vectors. He also explains affine motion prediction, allowing blocks to scale, rotate, change aspect ratio and shear. Finally Christian discusses the performance possible from the codec.

To find out more about VVC, including the content-based tuning such as for screen graphics, which is partly where the ‘versatile’ in VVC’s name comes from, listen to this talk, from 19 minutes in, given by Benjamin Bross from Fraunhofer. For Christian’s summary of all this year’s new MPEG codecs, see his previous video in the series.

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Speaker

Christian Feldmann Christian Feldmann
Team Lead, Encoding
Bitmovin

Video: The Video Codec Landscape 2020

Posted on by Russell Trafford-Jones

2020 has brought a bevvy of new codecs from MPEG. These codecs represent a new recognition that the right codec is the one that fits your hardware and your business case. We have the natural evolution of HEVC, namely VVC which trades on complexity to achieve impressive bit rate savings. There’s a recognition that sometimes a better codec is one that has lower computation, namely LCEVC which enables a step-change in quality for lower-power equipment. And there’s also EVC which has a license-free mode to reduce the risk for companies that prefer low-risk deployments.

Christian Feldmann from Bitmovin takes the stage in this video to introduce these three new contenders in an increasingly busy codec landscape. Christian starts by talking about the incumbents namely AVC, HEVC, VP9 and AV1. He puts their propositions up against the promises of these new codecs which are all at the point of finalisation/publication. With the current codecs, Christian looks at what the hardware and software support is like as well as the licencing.

EVC (Essential Video Codec) is the first focus of the presentation whose headline feature is more reliably licence landscape. The first offer is the baseline profile which has no licencing as it uses technologies that are old enough to be outside of patents. The main profile does require licencing and does allow much better performance. Furthermore, the advanced tools in the main profile can each be turned off individually hence avoiding patents that you don’t want to licence. The hope is that this will encourage the patent holders to licence the technology in a timely manner else the customer can, relatively easily, walk away. Using the baseline only should provide 32% better than AVC and the main profile can give up to a 25% benefit over HEVC.

LCEVC (Low Complexity Enhancement Video Coding) is next which is a new technique for encoding which is actually two codecs working together. It uses a ‘base’ codec at low resolution like AVC, HEVC, AV1 etc. This low fidelity version is then accompanied by enhancement information so that the low-resolution base can be upscaled to the desired resolution can be corrected with relevant edges etc. added. The overall effect is that complexity is kept low. It’s designed as a software codec that can fit into almost any hardware by using the hardware decoders in SoCs/CPUs (i.e. Intel QuickSync) plus the CPU itself which deals with the enhancement application. This ability to fit around hardware makes the codec ideal for improving the decoding capability to existing hardware. It stands up well against AVC providing at least 36% improvement and at worst improves slightly upon HEVC bitrates but with much-reduced encoder computation.

VVC (Versatile Video Coding) is discussed by Christian but not in great detail as Bitmovin will be covering that separately. As an evolution of HEVC, it’s no surprise that bitrate is reduced by at least 40%, though encoding complexity has gone up 10-fold. This is similar to HEVC compared to its predecessor AVC. VVC has some built-in features not delivered as standard before such as special modes for screen content (such as computer games) and 360-degree video.

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Speaker

Christian Feldmann Christian Feldmann
Lead encoding engineer,
Bitmovin

Video: High-Throughput JPEG 2000 (HTJ2K) for Content Workflows

Posted on by Russell Trafford-Jones

Published last year, high-throughput JPEG 2000 (HTJ2K) is an update to the J2K we know well in the broadcast industry making it much faster. Whilst JPEG 2000 has found a home in low-latency broadcast contribution, it’s also part of the archive exchange format (AXF) because, unlike most codecs, JPEG 2000 has a mathematically lossless mode. HTJ2K takes JPEG 2000 and replaces some of the compression with a much faster algorithm allowing for much faster decoding of well 10 to 28 times faster in many circumstances.

The codec market seems waking up to the fact that multiple types of codec are needed to support the thousands of use cases that we have in the Media and Entertainment and beyond. It’s generally well known that codecs live in a world where they are optimising bitrate at the expense of latency and quality. But the advent of MPEG 5 Part 2, also known as LCEVC show that there is value in optimising to reduce complexity of encoding. In some ways, this is similar to saying reduce the latency, but in the LCEVC example, the aim is to allow low-power or low-complexity equipment to deal with HD or UHD video where otherwise that might not have been possible. With HTJ2K we have a similar situation where it’s worth getting 10x more throughput when managing and processing your archive at the expense of 5% more bitrate.

This talk from the EBU’s Network Technology Seminar hears from Pierre-Anthony Lemieux and Michael Smith who explain the need for this codec and the advantages. One important fact is that the encoding itself hasn’t been changed, just some of the maths around it. This means that you can take previously encoded files and process them into HTJ2K without changing any of the video data. This allows lossy J2K files to be converted without any degradation due to re-encoding and minimises conversion time for lossless files. Another motivator for this codec is cloud workflows where speed of compression is important to reduce costs. Michael Smith also explores the similarities and differences of High-Throughput J2K with JPEG XS

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Speakers

Pierre-Anthony Lemieux Pierre-Anthony Lemieux
Sandflow Consulting
Michael Smith
Wavelet Consulting

Video: HLS and DASH Multi-Codec Encoding & Packaging

Posted on by Russell Trafford-Jones

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.

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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