Video: Comparison of EVC and VVC against HEVC and AV1

AV1’s royalty-free status continues to be very appealing, but in raw compression is it losing ground now to the newer codecs such as VVC? EVC has also introduced a royalty-free model which could also detract from AV1’s appeal and certainly is an improvement over HEVC’s patent debacle. We have very much moved into an ecosystem of patents rather than the MPEG2/AVC ‘monoculture’ of the 90s within broadcast. What better way to get a feel for the codecs but to put them to the test?

Dan Grois from Comcast has been looking at the new codecs VVC and EVC against AV1 and HEVC. VVC and EVC were both released last year and join LCEVC as the three most recent video codecs from MPEG (VVC was a collaboration between MPEG and IRU). In the same way, HEVC is known as H.265, VVC can be called H.266 and it draws its heritage from the HEVC too. EVC, on the other hand, is a new beast whose roots are absolutely shared with much of MPEG’s previous DCT-based codecs, but uniquely it has a mode that is totally royalty-free. Moreover, its high-performant mode which does include patented technology can be configured to exclude any individual patents that you don’t wish to use thus adding some confidence that businesses remain in control of their liabilities.

Dan starts by outlining the main features of the four codecs discussing their partitioning methods and prediction capabilities which range from inter-picture, intra-picture and predicting chroma from the luma picture. Some of these techniques have been tackled in previous talks such as this one, also from Mile High Video and this EVC overview and, finally, this excellent deep dive from SMPTE in to all of the codecs discussed today plus LCEVC.

Dan explains the testing he did which was based on the reference encoder models. These are encoders that implement all of the features of a codec but are not necessarily optimised for speed like a real-world implementation would be. Part of the work delivering real-world implementations is using sophisticated optimisations to get the maths done quickly and some is choosing which parts of the standard to implement. A reference encoder doesn’t skimp on implementation complexity, and there is seldom much time to optimise speed. However, they are well known and can be used to benchmark codecs against each other. AV1 was tested in two configurations since

AV1 needs special treatment in this comparison. Dan explains that AV1 doesn’t have the same approach to GOPs as MEPG so it’s well known that fixing it’s QP will make it inefficient, however, this is what’s necessary for a fair comparison so, in addition to this, it’s also run in VBR mode which allows it to use its GOP structure to the full such as AV1’s invisible frames which carry data which can be referenced by other frames but which are never actually displayed.

The videos tested range from 4K 10bit down to low resolution 8 bit. As expected VVC outperforms all other codecs. Against HEVC, it’s around 40% better though carrying with it a factor of 10 increase in encoding complexity. Note that these objective metrics tend to underrepresent subjective metrics by 5-10%. EVC consistently achieved 25 to 30% improvements over HEVC with only 4.5x the encoder complexity. As expected AV1’s fixed QP mode underperformed and increased data rate on anything which wasn’t UHD material but when run in VBR mode managed 20% over HEVC with only a 3x increase in complexity.

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Speaker

Dan Grois Dan Grois
Principal Researcher,
Comcast

Video: MPEG-5 Essential Video Coding (EVC) Standard

Learning from the patent miss-steps of HEVC, MPEG have released MPEG-5 EVC which brings bitrate savings, faster encoding and clearer licencing terms including a royalty-free implementation. The hope being that with more control over exposure to patent risk, companies large and small will adopt EVC as they improve and launch streaming services now and in the future.

At Mile High Video 2020, Kiho Choi introduced the MPEG 5 Essential Video Coding. Naturally, the motivation to produce a new codec was partly based on the continued need to reduce video bitrates. With estimates of the video traffic share on the internet, both now and in the future all hovering between 75% and 90% any reduction in bitrate will have a wide benefit, best exemplified by Netflix and Facebook’s decision to reduce the bitrate at the top of their ABR ladder during the pandemic which impacted the quality available to viewers. The unspoken point of this talk is that if the top rung used EVC, viewers wouldn’t notice a drop in quality.

The most important point about EVC, which is in contrast to the MPEG/ISO co-defined standard form last year, VVC, is that it provides businesses a lot of control over their exposure to patent royalties. It’s no secret that much HEVC adoption has been hampered by the risk that large users could be approached for licencing fees. Whilst it has made its way into Apple devices, which is no minimal success, big players like ESPN won’t have anything to do with it. EVC tackles this problem in two ways. One is to have a baseline profile which provides bitrate savings over its predecessors but uses a combination of technologies which are either old enough to not be eligible for royalty payments or that have been validated as free to use. Companies should, therefore, be able to use this level of codec without any reasonable concern over legal exposure. Moreover, the main profile which does use patentable technologies allows for each individual part of the profile to be switched off meaning anyone encoding EVC has control, assuming the vendor makes this possible, over which technologies they are using and hence their exposure to risk. Kiho points out that this business-requirements-first approach is new and in contrast to many codecs.

Kiho highlights a number of the individual tools within both the baseline and main codecs which provide the bitrate savings before showing us the results of the objective and subjective testing. Within the EVC docs, the testing methodology is spelt out to allow EVC to be compared against predecessors AVC and HEVC. The baseline codec shows an improvement of 38% against 1080p60 material and 35% for UHD material compared to AVC doing the same tasks yet it achieves a quicker encoder (less compute needed) and the decode is approximately the same. The main profile, being more efficient is compared against HEVC which is, itself, around 50% more efficient than AVC. Against HEVC, Kiho says, EVC main profile produces an improvement of around 30% encoding gain for UHD footage and 25% for 1080p60 footage. Encoding is close to 5x longer and decoder is around 1.5x longer than HEVC.

Kiho finishes by summarising subjective testing of SDR and HDR videos which show that, in contrast to the objective savings which are calculated by computers, in practice perceived quality is higher and enables a higher bitrate reduction, a phenomenon which has been seen in other codec comparisons such LCEVC. SDR results show a 50% encoding gain for 4K and 30% for 1080p60 against AVC. Against HEVC, the main profile is able to deliver 50% coding gains for 4K content and 40% for 1080p60. For HDR, the main profile provides an approximately 35% encoding gain for both 1080p60 and 4k.

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Speakers

Kiho Choi Kiho Choi
Senior Engineer & Technical Lead for Multimedia Standards at Samsung Electronics
Lead Editor of MPEG5 Part 1 Essential Video Coding

The New Video Codec Landscape – VVC, EVC, HEVC, LCEVC, AV1 and more

In the penultimate look back at the top articles of 2020, we recognise the continued focus on new codecs. Let’s not shy away from saying 2020 was generous giving us VVC, LCEVC and EVC from MPEG. AV1 was actually delivered in 2018 with an update (Errata 1) in 2019. However, the industry has avidly tracked the improved speeds of the encoder and decoder implementations.
Lastly, no codec discussion has much relevance without comparing to AV1, HEVC and VP9.

So with all these codecs spinning around it’s no surprise that one of the top views of 2020 was a video entitled “VVC, EVC, LCEVC, WTF? – An update on the next hot codecs from MPEG”. This video was from 2019 and since these have all been published now, this extensive roundup from SMPTE is a much better resource to understand these codecs in detail and in context with their predecessors.

Click here to read the article and watch the video.

The article explains many of the features of the new codecs: both how they work and also why there are three. Afterall, if VVC is so good, why release EVC? We learn that they optimise for different features such as computation, bitrate and patent licensing among other aspects.

Speakers

Sean McCarthy Sean McCarthy
Director, Video Strategy and Standards,
Dolby Laboratories
Walt Husak Walt Husak
Director, Image Technologies,
Dolby Laboratories

Video: Early Live Trials of VVC & EVC for OTT Delivery

Much of 2020 was spent looking forward to the release of VVC, EVC and LC-EVC. A trio of MPEG standards fitting different use cases across this industry and beyond. Now they’ve all been released, it’s time to filter through finding which are the right fit for your workflows.

In this video, Thibaud Biatek from ATEME looks at using EVC and VVC for online streaming. EVC, is the Essential Video Codec, and VVC stands for the Versatile Video Codec. If you’d like to know more about the codecs themselves, check out this video talking about all of them. The driver for new codecs highlighted in the video is that internet traffic is over 70% video. But taking a step back, we need to remember that these codecs all come delivering more than just compression savings. Some, like LCEVC bring easier compression on embedded systems and easier decoding for AI applications. VVC represents the state of the art in compression techniques and EVC offers a totally royalty-free encoding option which is missing from all other MPEG codecs.

MPEG are very open that VVC is the same fundamental design as MPEG 2 was, it’s the techniques in each functional block which have improved in both quantity and ability that marks the difference. As such, Thibaud notes that you can create the same base code for an EVC codec as for VVC, thus you only need one software library to deliver an encode for both codecs. If you look at partitioning the screen into blocks, we see that VVC does everything EVC does but ads the ability to have diagonals. Screen Content Coding (SCC) is a speciality of VVC which adds it as a standard capability, unlike HEVC which had it optional. EVC also has SCC but only contains Intra Block Copy to implement it; VVC has three more on top of IBC.

Thibaud outlines how ATEME have done their initial implementations of VVC and EVC. Though they are not yet full implementations, they are seeing notable improvements over HEVC, particularly for VVC’s encoding of 8K which is attributed to the larger block sizes allowed in partitioning. He then takes us through the trials to date which have involved UHD VVC over satellite to the current test which is a real-time VVC encode to a CMAF ladder of 720p, 1080p and 2160p. In partnership with Akamai, this was then distributed as CMAF to the end-user which was using IETR’s openVVC decoder.

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Speaker

Thibaud Biatek Thibaud Biatek
Reasearch & Innovation Engineer
ATEME