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.
The title says it all! Alex Converse speaks here at the San Fancisco Video Tech meet up while he was working at Google discussing the ins and outs of AAC – and since he implemented an AAC decoder himself, he should know a thing or two about it.
Sure enough, Alex delivers by talking about the different version of AAA that have been around since MPEG 2 AAC through to the high efficiency AACs we have seen more recently.
Walking through the AAC Encoder block diagram we look at each of the different sections from sampling, MDCT (a type of Fourier transform) to psychoacoustic processing, stereo processing and more.
We then start to look at the syntax for the way the streams are structured which brings us in to understanding the AAC channel modes, and the enhanced mechanisms for encoding and processing used by the later versions of AAC including HE-AAC V2.
Alex finished with quick look at low delay codecs and a Q&A.
A great, detailed, overview of AAC. Ideal for developers and those who need to fully understand audio.
VP9 is a well-known codec, but it hasn’t seen many high-profile, live deployments which makes Twitch’s move to deliver their platform using VP9 in preference over AVC all the more interesting.
Here, Yueshi Shen from Twitch, explains the rationale for VP9 by explaining the scale of Twitch and looking at their AVC bitrate demands. He explains the patent issues with HEVC and VP9 then looks at decoder support across devices and platforms. Importantly, encoder implementation is examined leading to Twitch’s choice of FPGA to provide live encoding.
Yueshi then looks at the potential of AV1 to Switch_Frame to provide low-latency broadcast at scale.