Google’s WebM Project: What It Means for Online Video
Google has released the On2 VP8 video codec with an open-source license, along with the WebM container format, which combines VP8 video with Vorbis audio. The company also added WebM support to its HTML5 beta version of YouTube (just add
&webm=1 at the end of the video URL, in a supported browser). What is Google up to, and what does it mean for online video?
Read on to find out.
Video has continually presented a challenge to Google’s dream of a fully-indexable, searchable web. Adobe Flash continues to dominate web video, and while other technologies like Microsoft’s Silverlight offer certain advantages, they are all proprietary. Google has been a strong supporter of HTML5 video, which everyone from Apple to Microsoft, Mozilla, Opera, and others support as well.
The problem lies in the format of videos contained in HTML5 pages– Apple, Microsoft, and thus far Google had gone with H.264, the most widely-used codec for HD video. H.264 enjoys widespread software and hardware support, but it’s not free, and in order to include H.264 support, companies like Opera would have to pony up millions of dollars. Mozilla and Opera instead implemented HTML5 video in their browsers with support for the open-source Ogg Theora and Vorbis formats, but Theora is a dated codec with limited hardware acceleration support.
Google’s move changes everything: by open-sourcing VP8, a modern codec is now available freely for use online. The WebM project lists an impressive array of launch partners, from ARM to Nvidia, AMD, Qualcomm, and now even Adobe. Google released a patch adding WebM support to ffmpeg, along with DirectShow filters to add playback support in Windows (Gstreamer plugins for Linux should be arriving soon). Test builds of Firefox, Chrome, and Opera are available with WebM support included.
Google’s likely to run into trouble with the MPEG-LA, which is sure to claim that WebM infringes on its members’ intellectual property and requires licensing royalties. For now, though, the WebM FAQ reads, “Some video codecs require content distributors and manufacturers to pay patent royalties to use the intellectual property within the codec. WebM and the codecs it supports (VP8 video and Vorbis audio) require no royalty payments of any kind. You can do whatever you want with the WebM code without owing money to anybody.”
Microsoft tried similarly to release its Windows Media Video 9 HD format (the VC-1 standard) as a royalty-free codec but soon thereafter was forced to create a patent licensing pool.
Is it any better than H.264?
Even beyond the 800-lb gorilla of licensing issues, not all’s happy in WebM-land. The first in-depth technical analysis of the WebM format is quite negative. Jason Garrett-Glaser of the x264 project concluded that “Overall, VP8 appears to be significantly weaker than H.264 compression-wise. The primary weaknesses mentioned above are the lack of proper adaptive quantization, lack of B-frames, lack of an 8×8 transform, and non-adaptive loop filter. With this in mind, I expect VP8 to be more comparable to VC-1 or H.264 Baseline Profile than with H.264. Of course, this is still significantly better than Theora, and in my tests it beats Dirac quite handily as well.”
Garrett-Glaser also writes that “VP8 is simply way too similar to H.264. A pithy, if slightly inaccurate, description of VP8 would be ‘H.264 Baseline Profile with a better entropy coder’. Though I am not a lawyer, I simply cannot believe that they will be able to get away with this, especially in today’s overly litigious day and age.”
Gregory Maxwell wrote in to the Wikimedia developer list that Garrett-Glaser is “comparing a very raw, hardly out of development, set of tools to his own project – which is the most sophisticated and mature video encoder in existence,” and explains that “x264 contains a multitude of pure encoder side techniques which can substantially improve quality and which could be equally applied to VP8. For an example of the kinds of pure encoder side improvements available, take a look at the most recent improvements to Theora.”
“VP8 is more computationally complex than Theora, but roughly comparable to H.264 baseline,” Maxwell wrote, “And it compares pretty favourably with H.264 baseline, even without an encoder that doesn’t suck. This is all pretty good news.”
Opera’s Haavard also points out that Garrett-Glaser’s analysis shows that VP8 did quite well against H.264 Baseline, which is the only H.264 format with hardware acceleration on platforms like the iPhone (and thus the only relevant comparison for web video).
Microsoft announced that Internet Explorer 9 will support VP8 in HTML5 video, but only if the VP8 codec is installed on the computer. While this means that IE9 technically supports VP8/WebM to the same degree that it supports H.264, Microsoft ships Windows 7 with an H.264 codec built-in, while VP8/WebM will have to be installed separately. That might be a deal-breaker for many users and, if not properly addressed, could present a serious challenge to native HTML5 WebM adoption.
Meanwhile Zencoder has added support for VP8, and video.js now offers web developers a player that can switch between h.264, OGG Theora, and VP8. On the mobile front, VP8 support for Android browsers is in progress, and an ARM blog post says that phones with ARMv7-class processors like Cortex-A8 and Qualcomm Snapdragon “will be able to take advantage of WebM” through the CPU’s NEON SIMD engine. The problem is that the phones’ GPUs and video engines currently lack native VP8 support, so VP8 video may still consume a lot more power than H.264 playback.
Apple remains the only major industry player that has yet to touch WebM. The company is quite committed to H.264 in HTML5 and has announced no plans to support WebM in Safari or QuickTime. When emailed for comment on WebM video, Apple CEO Steve Jobs simply replied with a link to Jason Garret-Glaser’s critique of the format, mentioned above.
Google is pushing hard for WebM, and as the force behind YouTube, the company does wield tremendous influence in the realm of web video. But with technical questions lingering about the format’s efficiency and concerns about hardware acceleration (particularly on mobile devices), the lack of native support (without separate VP8 codec installation) in Internet Explorer on Windows and a possibly obstructive Apple, the format still has many hurdles to clear before making a meaningful impact on the web.