Steve Jobs has apparently claimed that a patent pool is being assembled to "go after" Ogg Theora, the open source video codec used by the latest browsers from Google, Mozilla, and Opera.

The claim was made in an email the Apple CEO appears to have sent in response to an open source software advocate who questioned Apple's attachment to the patented H.264 codec.

On Thursday, Hugo Roy, an activist with the Free Software Foundation Europe, sent an email to Steve Jobs in response to the Apple CEO's much-discussed open letter on Adobe Flash. The note praised Jobs for his letter - in which he reiterated the company's commitment to HTML5 and other "open standards" - but Roy also made a point of telling Jobs that such talk of open standards should not include H.264.

"May I remind you that H.264 is not an open standard?" Roy wrote in a missive also posted to the web. "This video codec is covered by patents...This is why Mozilla Firefox and Opera have not adopted this video codec for their HTML5 implementation, and decided to choose Theora as a sustainable and open alternative."

Roy sent his note to what is believed to be Steve Jobs' email address - sjobs@apple.com - and three hours later, he received a reply.

"All video codecs are covered by patents," read the reply. "A patent pool is being assembled to go after Theora and other 'open source' codecs now. Unfortunately, just because something is open source, it doesn't mean or guarantee that it doesn't infringe on others patents. An open standard is different from being royalty free or open source."

The email's headers indicate the message did indeed come from Jobs - the Apple boss has sent several emails of late that have turned up on the web - and Roy tells The Reg he has no reason to believe that the email is less than genuine.

In the email, Jobs does not say who is assembling the alleged patent pool or what patents are involved or what "other 'open source' codecs" he's referring to. And it's unclear whether Apple is part of the pool. But the prospect of such an attack is of grave concern the open source world.

"Multimedia codecs are one of the worst patent minefields out there, enforcement is aggressive and there's no such thing as a video standard 100% unencumbered by patents," Florian Mueller, another open source advocate, says in an email to The Reg. "There are too many software patents out there to perform reliable clearance and patent offices often grant new patents on old ideas."

Ogg Theora is based on the VP3 codec, which was released into the public domain by On2 Technologies in 2001 under an irrevocable free license. Mozilla, Google, and Opera tried to make it part of the HTML5 standard, but they faced hefty opposition from Apple. As it stands, the HTML5 video standard does not specify a codec, so browser makers are free to use whatever codec they like.

Mozilla, Firefox, and Opera use Ogg. Apple's Safari uses H.264. Google uses both. And though Internet Explorer 8 does not support the HTML5 video tag, Microsoft will include H.264-happy HTML5 with IE9. Today, with a blog post, Microsoft also argued that the rights to "other codecs are less clear."

Google recently acquired On2 Technologies, and it's rumored that the company will open source the latest On2 codec, VP8, to create a license-free codec that offers better performance than Ogg. Google has said that it hasn't adopted Ogg exclusively because it's not fast enough for a site like YouTube.

H.264 is licensed by MPEG LA, which controls a patent pool around the technology, and Apple is a contributor to the H.264 patent pool. Presumably, in his email, Jobs is referring to some other pool. But it's worth noting that in the past, the MPEG LA has said it "believes" that Ogg infringes at least some of its patents.

Apple has said in the past that it avoids Ogg because of an "uncertain patent landscape." But this is the first mention of a pool designed to "go after" the open source codec. The company has also indicated that it prefers H.264 because Ogg has limited hardware support.

Even if you set the mystery patent pool claim to one side, the alleged Jobs email doesn't do much to clarify Apple's position. "I'm completed confused by it," Roy tells The Reg. The last sentence of the email - "an open standard is different from being royalty free or open source" - is a truth that doesn't really respond to what Roy was trying to say in his original note. And he questions why Jobs would even respond.

But in recent days, the man has exhibited what would seem to be a compulsive tendency to answer his critics. ®