Saturday, June 19, 2021

WebM VP8 Video Codec Won’t End Theora

At Google’s I/O conference, the search giant this week released the VP8 video codec as open source and launched the WebM project for online video. The effort has already been embraced by multiple browser vendors.

With VP8, Google (NASADAQ: GOOG) is open sourcing technology it acquired when it bought video firm ON2 technologies last year. VP8 competes with the H.264 proprietary codec, as well as the open source Theora codec. Among the big backers of Theora is Mozilla, which has supported Theora as part of its HTML5 video implementation since the Firefox 3.5 release last year.

With Mozilla now backing WebM, what does that mean for Theora?

“We don’t have any plans to drop support for Theora. We’ve seen good uptake for it,” Mike Shaver, vice president of engineering at Mozilla, told “I don’t think there is any reason for us to take it (Theora) out, so we’re planning on supporting both codecs going forward.”

From an engineering perspective, Mozilla has had development resources tasked with improving Theora. Now that Mozilla is also supporting VP8, Shaver doesn’t expect it to impact the continued contributions to Theora.

“We’re going to invest in video where we see the best opportunity to contribute,” Shaver said. “Right now we’re looking at getting situated with VP8. We’ve got some people looking at improvements there. But we’ll continue to contribute to Theora as it makes sense as well.”

He pointed out that Mozilla just wrapped up a Digital Signal Processing (DSP) support project for Theora.

Comparing the two codec, VP8 has different performance characteristics than Theora. Shaver explained that when looking at video there are a number of factors to consider, including quality by bit rate. From that perspective, the VP8 is comparable with the proprietary H.264 codec, he said, adding that VP8 right now also has a better quality per bit rate than Theora.

The other factor to consider is how much effort is required to decode a codec, which can affect power drain on mobile devices. Shaver said that Theora and VP8 are both pretty simple to decode.

“Some of the Theora tools for doing constant quality at variable bit rates are very popular right now and we don’t see that out of the box with WebM today,” Shaver said. “We’re going to follow the lead of people that are building the great video experiences and the ones that are consuming them to see which video formats they are using and where improvements are necessary. That’s where we’ll invest.”

As to which video codec will be the default on Mozilla Firefox for HTML 5 video, it’s a question that is determined by the content authors.

“We will process the source elements in order until we find an element we understand,” Shaver said. “I think Theora or VP8 will make sense for different content providers, but there really isn’t a notion of a default in the way the HTML video source processing works.”

While Google and Mozilla are among the key browser vendor backers for VP8, future versions of Microsoft’s Internet Explorer 9 browser will also support the codec.

“In its HTML5 support, IE9 will support playback of H.264 video as well as VP8 video when the user has installed a VP8 codec on Windows,” Dean Hachamovitch, general manager of Microsoft’s Internet Explorer, wrote in a blog post.

Sean Michael Kerner is a senior editor at, the news service of, the network for technology professionals.

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