Guido Meardi Archives – The Broadcast Knowledge

MPEG released 3 codecs last year, VVC, LCEVC and EVC. Which one was unlike the others? LCEVC is the only one that is an enhancement codec, working in tandem with a second codec running underneath. Each MPEG codec from last year addressed specific needs with VVC aiming at comprehensive bitrate savings while EVC aims to push encoding further whilst having a patent-free base layer.

In this talk, we hear from Guido Meardi from V-Nova who explains why LVECV is needed and how it works. LCEVC was made, Guido explains, to cater to an increasingly crowded network environment with more and more devices sending and receiving video both in residential and enterprise. LCEVC helps by reducing the bitrate needed for a certain quality level but, crucially, reduces the computation needed to achieve good quality video which not only benefits IoT and embedded devices but also general computing.

LCEVC uses a ‘base codec’ which is any other codec, often AVC or HEVC, which runs at a lower resolution than the source video. By using this hybrid technique, LCEVC aims to get the best video compression out of the codec yet by running the encode at a quarter resolution, allowing this to be done on low-power hardware. LCEVC then deals with reconstructing two enhancement layers and a, relatively simple, super-resolution upsample. This is all achieved with a simple toolset and all of the LCEVC computation can be done in CPU, GPU or other types of computation; it’s not bound to hardware acceleration.

Guido presents a number of results from tests against a whole range of codecs from VVC to AV1 to plain old AVC. These tests have been done by a number of people including Jan Ozer who undertook a whole range of tests. All of these tests point to the ability of LCEVC to extend bandwidth savings of existing codecs, new and old.

Guido shows an example of a video only comprising edges (apart from mid-grey) and says that LCEVC encodes this not only better than HEVC but also with an algorithm two orders of magnitude less. We then see an example of a pure upsample and an LCEVC encode. Upsampling alone can look good, but it can’t restore information and when there are small textual elements, the benefit of having an enhancement layer bringing those back into the upsampled video is clear.

On the decode side, Guido presents tests showing that decode is also quicker by at least two times if nor more, and because most of the decoding work is involved in decoding the base layer, this is still done using hardware acceleration (for AVC, HEVC and other codecs depending on platform). Because we can still rely on hardware decoding, battery life isn’t impacted.

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Speakers

Guide Meardi
CEO & Co-Founder,
V-Nova

Video is so pervasive in our world that we need to move past thinking of codecs and compression being about reducing bitrate. That will always be a major consideration, but speed of compression and the computation needed can also be deal breakers. Millions of embedded devices need to encode video which don’t have the grunt available to the live AV1-encoding clusters in the cloud. Further more, the structure of the final data itself can be important for later processing and decoding. So we can see how use-cases can arise out needs of various industries, far beyond broadcast, which mean that codecs need to do more than make files small.

This year LCEVC from MPEG will be standardised. Called Low Complexity Enhancement Video Coding, this codec provides compression both where computing is constrained and where it is plentiful. Guido Meardi, CEO of V-Nova, talks us through what LCEVC is starting with a chart showing how computation has increased vastly as compression has improved. It’s this trend that this codec intends to put an end to by adding, Guido explains, an enhancement layer over some lower-resolution video. By encoding a lower-resolution, computational processing is minimised. When displayed, an enhancement layer allows this low resolution video to be sharpened again to bring it back to the original.

After demonstrating the business benefits, we see the block diagram of the encoder and decoder which helps visualise how this enhancement might be calculated and work. Guido then shows us what the enhancement layer looks like – a fairy flat image with lots of thin edges on it but, importantly, it also captures a lot of almost random detail which can’t be guessed by upsamplers. This, of course, is the point. If it were possible to upscale the low-resolution video and guess/infer all the data, then we would always do that. Rather, downscaling and upscaling is a lossy process. Here, that loss is worth it because of the computational gains and because the enhancement layer will put back much of what was once lost.

In order to demonstrate LCEVC’s ability, Guido shows graphs comparing LCEVC at UHD for x264 showing improvements of between 20 and 45% and image examples of artefacts which are avoided using LCEVC. We then see that when applied to AVC, HEVC and VVC it speeds up encodes at least two fold. Guido finishes this presentation showing how you can test out the encoder and decoder yourself.

The last segment of this video, Tarek Amara from Twitch sits down to talk with Guido about the codec and the background behind it. Their talk covers V-Nova’s approach to open source, licensing, LCEVC’s gradual improvements as it went through the proving process as part of MPEG standardisation plus questions from the floor.

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Speakers

	Guido Meardi CEO & Co-Founder, V-Nova
	Tarek Amara Principal Video Specialist, Twitch

LCEVC (Low Complexity Enhancement Video Coding) is a low-complexity encoder/decoder is in the process of standardisation as MPEG-5 Part 2. Instead of being an entirely new codec, LCEVC improves detail and sharpness of any base video codec (e.g., AVC, HEVC, AV1, EVC or VVC) while lowering the overall computational complexity expanding the range of devices that can access high quality and/or low-bitrate video.

The idea is to use a base codec at lower resolution and add additional layer of encoded residuals to correct artifacts. Details are encoded with directional decomposition transform using a very small matrix (2×2 or 4×4) which is efficient at preserving high frequencies. As LCEVC uses parallelized techniques to reconstruct the target resolution, it encodes video faster than a full resolution base encoder.

LCEVC allows for enhancement layers to be added on top of existing bitstreams, so for example UHD resolution can be used where only HD was possible before thanks to sharing decoding between the ASIC and CPU. LCEVC can be decoded via light software processing, and even via HTML5.

In this presentation Guido Meardi from V-Nova introduces LCEVC and answers a few imporant question including: is it suitable for very high quality / bitrates compression and will it work with future codecs. He also shows performance data and benchmarks for live and VoD streaming, illustrating the compression quality and encoding complexity benefits achievable with LCEVC as an enhancement to H.264, HEVC and AV1.

Watch now!

Speaker

Guido Meardi
CEO and Co-Founder
V-Nova Ltd.

Date: Today, 23rd July, 2018 16:00 BST / 8am PST

This joint webinar from the IABM and V-Nova, will dive into the current state of the compression market, exploring new technologies and assessing compression costs and benefits to broadcasters, operators and OTT providers.

“More with less,” this has always been the compression mantra since the beginning. With the rise of new media and the emergence of immersive formats such as UHD and VR, compression vendors have been again asked to deliver better quality at a reduced bit-rate.

Industry trends driving demand for improved video compression
Shift from hardware to software (and virtualisation) – impact on compression vendors and benefits for operators
The benefits of next-generation video compression for AVOD and SVOD services. What are the dynamics? How much of an effect can it have on a streaming video business?
The rise of AI – how artificial intelligence can improve compression economics
Immersive formats – UHD/VR demand by end-users; economics of delivering these formats and how best to do so
HEVC, AV1 and PERSEUS Plus – the various factors dictating what codec to choose and in which scenarios they have most value