We’ve got used to a world of near-universal AVC/h.264 support, but in our desire to deliver better services, we need new codecs. VVC is nearing completion and is attracting increasing attention with its ability to deliver better compression than HEVC in a range of different situations.
Benjamin Bross from the Fraunhofer Institute talks at Mile High Video 2019 about what Versatile Video Coding (VVC) is and the different ways it achieves these results. Benjamin starts by introducing the codec, teasing us with details of machine learning which is used for block prediction and then explains the targets for the video codec.
Next we look at the bitrate curves showing how encoding has improved over the years and where we can expect VVC to fit in before showing results of testing the codec as it exists today which already shows improvement in compression. Encoding complexity and speed are also compared and as expected complexity has increased and speed has reduced. This is always a challenge at the beginning of a new codec standard, but is typically solved in due course. Benjamin also looks at the effect of resolution and frame rate on compression efficiency.
Every codec has sets of tools which can be tuned and used in certain combinations to deal with different types of content so as to optimise performance. VVC is no exception and Benjamin looks at some of the highlights:
Screen Content Coding – specific tools to encode computer graphics rather than ‘natural’ video. With the sharp edges on computer screens, different techniques can produce better results
Reference Picture Rescaling – allows resolution changes in the video stream. This can also be used to deliver multiple resolutions at the same time
Independent Sub Pictures – separate pictures available in same raster. Allows, for instance, sending large resolutions and allowing decoders to only decode part of the picture.
The codec world is fragmenting. None of the new entrants on to the market is expected to ever gain the universal status that AVC enjoys. This panel from Streaming Media East takes a look at how to prepare for this.
The panel kicks off discussing the differences between AVC and HEVC, VP9 and AV1 and moves on to discuss the pros and cons of supporting multiple codecs. Tarek from Twitch explains its partial adoption of VP9 – the reasons that it makes sense but the overheads which it brings the business.
Vittorio Giovara from Vimeo explains their reasons for using HEVC including their drive to be able to encode and deliver 10-bit video. Ellation’s Subhrendu Sarakar makes the point that managing codec changes and bitrate changes needs to be done carefully to ensure viewers that notice the change understand them and don’t feel there has been a reduction of quality.
After a brief discussion of encoding strongly characterised video types such as anime and gaming, the conversation moves on to AV1 and migrating from VP9 and there is an audience question on HEVC licensing and the lack of use of SVC (Scalable Video Coding)
It’s now relatively well known that Twitch deployed VP9 using FPGAs rather than as a software encoder which was the only way to get the real-time speed at 1080p60. The panel discusses encoding speed both in the encoder and decoder for VP9 and AV1 then finishes with a Q&A from the audience.
There continues to be fervent activity in codec development and it’s widely expected that there won’t be a single successor to AVC (h.264). Vying for one of the spots is AV1 but also MPEG’s VVC.
In this talk at SMPTE 2018, Julien Le Tanou from MediaKind compares the coding tools used by VVC and AV1 and explains the methodology he uses to compare the two codecs. We see the increase in decoding time compared to HEVC required for VVC as well as the famously slow AV1. We also see the bitrate savings with VVC performing better.
Julien also presents subjective results which are not correlated to the objective results and explains reasons for this.
Julien Le Tanou
Senior Engineer, Video Compression,
AV1 and VVC are both new codecs on the scene. Codecs touch our lives every day both at work and at home. They are the only way that anyone receives audio and video online and television. So all together they’re pretty important and finding better ones generates a lot of opinion.
So what are AV1 and VVC? VVC is one of the newest codecs on the block and is undergoing standardisation in MPEG. VVC builds on the technologies standardised by HEVC but adds many new coding tools. The standard is likely to enter draft phase before the end of 2019 resulting in it being officially standardised around a year later. For more info on VVC, check out Bitmovin’s VVC intro from Demuxed
AV1 is a new but increasingly known codec, famous for being royalty free and backed by Netflix, Apple and many other big hyper scale players. There have been reports that though there is no royalty levied on it, patent holders have still approached big manufacturers to discuss financial reimbursement so its ‘free’ status is a matter of debate. Whilst there is a patent defence programme, it is not known if it’s sufficient to insulate larger players. Much further on than VVC, AV1 has already had a code freeze and companies such as Bitmovin have been working hard to reduce the encode times – widely known to be very long – and create live services.
Here, Christian Feldmann from Bitmovin gives us the latest status on AV1 and VVC. Christian discusses AV1’s tools before discussing VVC’s tools pointing out the similarities that exist. Whilst AV1 is being supported in well known browsers, VVC is at the beginning.
There’s a look at the licensing status of each codec before a look at EVC – which stands for Essential Video Coding. This has a royalty free baseline profile so is of interest to many. Christian shares results from a Technicolor experiment.