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I have worked really hard to fix that D-STAR issue. See FreeDV and Codec2. We expect to have that on VHF/UHF soon.

Which codecs is Mr Perens referring to which are standard, and yet secret ("this closed codec was the first time that we had a technology that we weren't allowed to understand and to build by ourselves")?

He's talking about Dstar from Icom using the AMBE codec. A cool and interesting mode. Totally non-free of course. Technically you can implement the data side without the speech codec if you want, but the voice mode is more popular. Its standard in that if you wanna buy off the shelf appliance-style ham radio gear to do digital voice, this is it, aside from some experimental mototurbo and trunking implementations.

I believe the codec is a product of DVSI. What Icom and the equipment owners intend to do if DVSI goes rogue or closes up shop is not apparent, superficially the answer seems to be "give up". Thats what happens when you base a business on someone elses proprietary software... its risky.

Bruce is slightly in error about "build by ourselves". You can build/steal/reverse engineer/replicate/copy ABME in your basement all you want. You just can't sell it. Its kind of like SSB, where the 1923 patent held the technology back for quite awhile. Someday AMBE will be off patent and "free-ish" at which point it'll be rather popular. I was fooling around with the idea of crossing a T2S with a dictionary of AMBE data. So your speech to text hears me say "uh" and the dictionary of AMBE data says that "uh" is bitstream 10101010 or whatever, ditto the opposite direction. Totally illegal to redistribute until the patent runs out, but an interesting and obvious idea none the less. I "know of" dstar repeaters that fool around with recording the bitstream and playing it back bit for bit to make announcements rather than recording and injecting audio for announcements or just not doing announcements.

Finally a subjective opinion is G.729 is terrible voice quality and is just as patented and licensed as AMBE its just that AMBE crushes it in subjective testing. Its kinda like "why use microsoft Bob if you can use XP instead..."

I think the patent free codec he's talking about is CODEC2

http://en.wikipedia.org/wiki/Codec2

http://codec2.org/

Lossless is a different game and extreme voice compression is still a work in progress (I predict this can go a lot further yet, ending up as almost a MIDI file for the human larynx with a compression layer on top that models typical speech production--this may or may not be language neutral).

It pretty much is. Check out codec2

"Opus covers basically the entire audio-coding application space"

Maybe I didn't look hard enough but I didn't see anything about how well it handles getting some of it's data corrupted. I only see comparisons of how it works at different bitrates. This is important for radio applications as there will always be interference and some percentage of the received bits will be wrong. That is why for example we don't see Amateur Radio operators using Speex. If this truly covers everything then we don't need codec2 http://codec2.org/ but from what I see it just sounds like a new ogg vorbis which is useful through a wider range of bitrates.

For low bit rate voice (down to 1400bit/s) you can use codec2.

The original rationale for Codec2 is at Codec2.org. I've been promoting this issue for about four years, as I was bothered by the proprietary nature of the AMBE codec in D-STAR. But I didn't have the math, etc., to do the work myself. It was really fortunate that David became motivated to do the work without charge. He has a Ph.D. in voice coding. By the way, look over his web site rowetel.com for the other work he's done: two really nice Open Hardware projects - a PBX and a mesh telephony device, an Open Source echo canceler for digital telephony, used in Asterisk and elsewhere, and his own electric car conversion. He'd be my nomination for the MacArthur grant.

Bruce Perens, K6BP, proposed replacing the proprietary AMBE codec with a new open codec. David Rowe, VK5DGR, has strted a project to replace the codec, but needs support in order to continue.

Anyone willing to help out or donate?

-molo