State Of Play : The WebM vs H.264 Debate

This is an installment of our ongoing State of Play series, designed to offer insight into new evolutions and significant issues in the online video industry.

About a year ago, we wrote about video formats as part of an introduction to multimedia containers and codecs. Since then, the online video landscape has changed drastically by Google's acquisition of On2 and the subsequent launch of WebM as an open source video format. In this post, we'll try to shed some light on the ongoing 'WebM vs H.264' debate.

WebM / H264 Formats

WebM format

On May 9, 2010 Google released WebM as an open and royalty-free video compression format for the web. The WebM project defines a container format based on a subset of the Matroska media container, which is designed to hold VP8 video and Vorbis audio streams.

H.264 video

H.264 is a video codec standard developed by the ITU-T Video Coding Experts Group (as H.264) together with the ISO/IEC Moving Picture Experts Group (as MPEG-4 Part 10, Advanced Video Coding, or AVC). During the last couple of years, it has become the de-facto compression standard for online video. When used in Flash or HTML5 video, it is often being used together with the AAC audio codec and stored inside of an MPEG-4 container. Other possible container formats include .mov (QuickTime), .3gp and .3gp2 (mobile) and .f4v (Flash).

Openness and Licensing

A lot of attention has been drawn to the free and open nature of the WebM format, as opposed to H.264 which has a patent license administered by a private organization known as MPEG LA. On August 26, 2010 MPEG LA announced that H.264 encoded internet video will perpetually remain free for non-commercial use, which means that you will never have to pay royalties for distributing free internet video encoded via H.264. However, license fees are required for other types of usage such as subscription based content services and device manufacturers.

The WebM project, on the other hand, is offering its code under a standard BSD license. Google has irrevocably released all of its patents on VP8 as a royalty-free format, but provides no indemnification for costs incurred should a patent lawsuit arise. That means that anyone distributing WebM/VP8 could be on the hook for any patent-related fees that might come up.

MPEGLA logoOn February 11, 2011 MEPG LA announced that it is forming a patent pool and gathering claims from companies that believe they have patents essential to the VP8 codec, spurring uncertainty about a royalty-free future for WebM. The move resulted in an investigation by the US Justice Department to see whether MPEG LA is trying to stifle competition. Google reacted by launching a new community cross-licensing initiative, which was joined by consumer electronics manufacturers like Samsung, LG Electronics and Cisco.

There has also been some debate surrounding Google's assertion that it wants to 'enable open innovation'. There are now two viable branches of VP8, the one Google has retained in house, and another one expanded on by the open-source community. However, there's no third party entity that manages the evolution of the specification. And when it comes to important decisions like choosing the code to be used by hardware manufacturers for implementing silicon, Google will always have the final say - which is, incidentally, the same policy that Google is applying to other 'open source' projects/products like Android and Honeycomb.

Quality

H.264 is widely considered as today's most advanced video codec. By defining a set of encoding profiles and levels, the H.264 standard allows for playback on platforms with very divergent decoding capabilities. These profiles include a baseline profile (BP) aimed at applications with limited computing resources, a main profile (MP) intended as the mainstream consumer profile and a high profile (HiP) for HD and FullHD which requires lots of memory and processing power.

Quality seems to be the main point of criticism regarding WebM. Compression-wise, the standard is said to be comparable to the H.264 baseline profile. In reality, the encoder implementations are as important as the standard itself for evaluating quality. The Moscow State University’s Graphics and Media lab evaluated both the x264 decoder and the VP8 encoder and concluded that the latter shows “20-30% lower quality at average", while requiring slightly longer encoding times to reach the “normal” settings of x264 (baseline profile). However, WebM is judged to be performing significantly better than Theora or xvid. In contrast, a comparison by Streaming Media concluded that WebM is almost as good as H.264 "at most relevant data rates" for web video.

In terms of decoding speed, VP8 and H.264 seem to be relatively comparable. But H.264 already has a great deal of hardware support, which makes it decode faster in most real life circumstances. Particularly for portable devices, hardware acceleration is essential for video playback. In January 2011, the WebM project announced the availability of VP8 Hardware IP Designs and Chinese chip designer Rockchip announced the first processor with support for VP8. However, it will take time for WebM hardware acceleration to reach critical mass.

HTML5

HTML5 browser support for the video tagThe new HTML5 standard supports embedded multimedia, including video, audio, and dynamic graphics. The new <video> tag allows browsers to natively playback video, without needing plugins like Flash, Silverlight or QuickTime. However, disagreements in the W3C standards group resulted in an omission of a codec specification for the <video> tag. This has led to a stalemate, which is not likely to be resolved very soon. All browser vendors agree that their software should support the HTML5 <video> tag, but they can't agree on the video codec that will allow it. As a result, different browsers have native support for different video codecs.

On January 11, 2011 Google decided to drop support for H.264 in the Chromium open source browser (from which Chrome is built), in favor of WebM. This led to the current situation, in which Microsoft (IE 9) and Apple (Safari 5) support H.264, while Google (Chrome 12), Mozilla (Firefox 5) and Opera (10) support VP8 and Theora.

Both Apple and Microsoft, determined not to give Google control over the future of web video, have declared to be fully behind H.264 as the codec for HTML5 video going forward. Microsoft has even gone a step further, releasing plugins for Firefox and Chrome which allow them to play H.264 on Windows. Google in its turn has released a WebM plugin for Internet Explorer.

This division has been a major obstacle for the progress of HTML5 video. The majority of web video is currently encoded in H.264 and being played using Adobe Flash Player. Since this is still a viable option for all major browsers and H.264 also remains dominant on devices (Google has added WebM support to Android, but didn't remove support for H.264), there's no real incentive for video content owners to switch to HTML5.

VIDEO IN A Two-codec world

Even though H.264 is still dominant - according to MeFeedia, H.264 now accounts for 69% of all HTML5 video - WebM is expected to gradually gain market share, which may result in a two-codec world for the coming years. If your online videos are designed to stick around, you may want to start encoding into both formats. To do this transparently, Rambla customers can use their default hotfolder: simply upload your video files and they will get automatically published in both formats on the CDN. Developers can use our API's instead. For more information, take a look at our user guides or contact us.