Three Videos On Codec2 and Open Hardware

Bruce Perens writes "Codec2 is the Open Source ultra-low-bandwidth speech codec capable of encoding voice in 1200 Baud. FreeDV (freedv .org) is an HF (global-range radio) implementation that uses half the bandwidth of SSB, and without the noise. Here are three speeches about where it's going."

• David Rowe: Embedding Codec2: Open Source speech coding on a low-cost microprocessor, at Linux.conf.au 2014. YouTube, downloadable MP4.
• Bruce Perens: FreeDV, Codec2, and HT of the Future (how we're building a software-defined walkie-talkie that's smarter than a smartphone), at the TAPR/ARRL Digital Communications Conference 2013. Blip.tv, YouTube
• Chris Testa on the .Whitebox handheld software-defined radio design that is the RF portion of HT of the Future, which was also shown at the TAPR conference.

Comments

MOS?

[AK Marc]

I wouldn't trust a CODEC I can't even find a MOS for (yeah, I found some independent tests, but they varied wildly).

Code2 voice sample @4:50

[bill_mcgonigle]

http://www.youtube.com/watch?v=u4svoub6XcE&t=4m50s

This is pretty neat. Some high school friends and I were attempting to get voice working over 2400 baud c. 1990 (we wanted Internet phones). We never even came close, and thought we'd have to do phoenmic deconstruction to get that kind of data rate. This is pretty amazing for 1200 baud, even if it is almost 25 years later.

from codec2.org

[viperidaenz]

The way that current digital voice products for Radio Amateurs encode voice signals to digital bits is both trade-secret and patented.

Excuse me, but if something is patented, how can it be a trade secret?

Re:from codec2.org

[Bruce Perens]

Since I did this talk, a lot of information about AMBE has been revealed and there is a receive-only implementation in Open Source. The patents in general run out by 2015. But AMBE is still a relatively low-performance codec compared to ours.

Re:Latency?

[stevew]

I've used codec2 daily in the ghpsdr-alex branch for controlling SDR over Linux remotely.

It is deployed on the Android App glSDR that you can find in the Android Market.

The app provides a GUI with spectrum & waterfall along with Audio from the radio being controlled. Codec2 is used to provide a low-overhead transport that survives the Internet quite nicely.

I've used the app with my 4G phone quite successfully.

Now to the question of latency. When I connect to my own radio with a real-time playback PLUS the codec playback running at the same time, there is a fraction of a second delay - perhaps 100ms-200ms at a guess.

So bottom line is there are real applications for Ham Radio already deploying this technology.

KA6S