Industry Blog

Video Codecs in Close Battle

The battle between today’s leading video codecs — HEVC and VP9 — will be a closer fight than we saw between the leaders in the prior generation, VP8 and AVC. There may be room in the market for both – at least in the short term.

The Advanced Video Codec (AVC, a.k.a. H.264) will likely remain the dominant, mature video codec for the mobile market in the short term. Content providers will not provide High Efficiency Video Codec (HEVC, otherwise known as H.265) or VP9 variants for mobile until a critical mass of mobile devices provide support. The mobile market will not have critical mass until hardware accelerated chipsets are available, and these devices permeate the market.

VP9 is the follow on to VP8, which Google used in its WebM format. VP8 was developed by On2 Technologies, who were acquired by Google in February 2010. WebM is a combination of the VP8 video codec, OGG Vorbis audio, and the Matroksa container format. All of which are open source. With WebM, Google attempted to exploit the chink in the AVC armour that it is a patented technology.

It is hard to predict a clear winner between HEVC and VP9.

Apple has shown no sign of adding support for VPx codecs, and maintains its support for the MPEG standards (AVC and HEVC). Given the popularity of Apple devices, HEVC is all but guaranteed a place in the ecosystem. The first 4K device from Apple should validate this.

At this point, comparative studies show HEVC to be the superior format. The situation may change over time as the codecs mature.

On paper, HEVC has 10 times the encoding complexity of AVC and twice decoding complexity. This means that modern laptop and high end mobile devices area already capable of decoding in software. The cost is a heavy battery drain, which can be addressed with hardware acceleration

The success of VP9 depends on support from clients and content providers, and in Google the owner of the standard has a large share of the client and content market.

YouTube already publishes VP9 content as variants in its DASH format, with no current support for HEVC. However if Apple releases a 4K-capable device using HEVC and maintains its stance in not supporting VP9, YouTube will be forced to either:

  • Encode 4K using AVC. Unlikely as the bandwidth costs would be prohibitive.
  • Do not provide 4K to Apple users. Again, an unlikely scenario.
  • Provide HEVC variants. The most likely outcome.

Also in question is the patent-free status of VP9. Given that Google had to license patents from the MPEG-LA patent pool for VP8, it is likely that VP9 also infringes patents in the MPEG-LA patent pool which has grown to include HEVC. It’s unclear if Google will need to license the technology from MPEG-LA and, if so, if MPEG-LA will be willing to grant the license or see an opportunity to hurt a competing format.

YouTube is currently providing VP9 content as a DASH variant. Netflix have chosen to use a HEVC encoding for their 4K TV service. This has punished the early adopters of 4K television, as the first models contained hardware support for AVC decoding only.

This makes the early release 4K equipment incompatible with the Netflix service.

4K video is unlikely to be delivered to devices on mobile networks in the short to medium term. Displays supporting 4K will only be supported on larger tablet screens, and so not applicable to the majority of mobile devices. In addition, even using the new generation codecs the bandwidth cost is simply too high. Even today on smartphone and tablet devices, content providers such as YouTube will serve a lower resolution to the same device on 3G than on WiFi due to the bandwidth demands.

However, 4K video will drive adoption of the new generation codecs in video publishing. Once the codec implementations and content publishing tools reach a level of maturity with HEVC/VP9, content publishers will have the ability to easily produce lower resolution versions of the content targeted at mobile devices using the next generation codecs, saving 40% to 50% in the bandwidth costs. At that point, hardware acceleration will become desirable on mobile devices to minimize the increased battery drain.

We are likely to see a lot of movement in this space over the coming year. As more 4K devices become available, more 4K content will become available. A clearer picture should then emerge on the adoption of HEVC and VP9, and use will filter down into lower resolution video. It is then that we will see the real impact on the mobile market.

One dark horse clouds the picture for next generation of video codecs. The Mozilla Foundation is working on a royalty-free codec named Daala. The project is in very early development, however Mozilla says its goal is “…to provide a free to implement, use and distribute digital media format and reference implementation with technical performance superior to H.265.”

This will be an interesting project to watch.
— Stephen Wright is a software architect with Openwave Mobility. He has 15 years of experience in software development for the telecommunications industry and currently specializes in content adaptation and optimization for mobile devices with a focus on delivering the best possible experience for mobile users browsing the web.

This blog was published by EE Times on Aug 25. Click Here!