Many companies would love to be using free codecs, unencumbered by patents, rather than paying for HEVC or AVC. Phil Cluff shows that, contrary to popular belief, it is possible stream with free codecs and get good coverage on mobile and desktop.
Phil starts off by looking at the codecs available and whether they’re patent encumbered with an eye to how much of the market can actually decode them. Free codecs and containers like WebM, VP8 etc. are not supported by Safari which reduces mobile penetration by half. To prove the point, Phil presents the results of his trials in using HEVC, AVC and VP8 on all major browsers.
Whilst this initially leaves a disappointing result for streaming with libre codecs on mobile, there is a solution! Phil explains how an idea from several years ago is being reworked to provide a free streaming protocol MPAG-SASH which avoids using DASH which is itself based on ISO BMFF which is patent encumbered. He then explains how open video players like video.js can be modified to decode libre codecs.
With these two enhancements, we finally see that coverage of up to 80% on mobile is, in principle, possible.
AV1 is famous for its promise to deliver better compression than HEVC but also for it being far from real-time. This talk has a demonstration of the world’s first real-time AV1 video call showing that speed improvement are on the way and, indeed, some have arrived.
Encoding is split into ‘tools’ so where you might hear of ‘h.264’ or ‘MPEG 2’, these are names for a whole set of different ways of looking at – and squeezing down – a picture. They also encompass the rules of how they should act together to form a cohesive encoding mechanism. (To an extent, such codecs tend to define only how the decode should happen, leaving encoding open to innovation.) AV1 contains many tools, many of which are complex and so require a lot of time even from today’s fast computers.
Cisco’s Thomas Davies, who created the BBC’s Dirac codec which is now standardised under SMPTE’s VC-2 standard, points out that whilst these tools are complex, AV1 also has a lot of them and this diversity of choice is actually a benefit for speed and in particular for the speed of software codecs.
After demonstrating the latency and bandwidth benefits of their live, bi-directional, AV1 implementation against AVC, Thomas looks at the deployment possibilities and of AV1. The talk finishes with a summary of what AV1 brings in benefits to sum up why this new effort, with the Alliance of Open Media, is worth it.
Cisco Media Engineering, UK
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.