Open Source DSTAR Voice??
by:  KE7HQY
June 6, 2010

Open Source DSTAR Voice — Codec2:

The DSTAR protocol is open and freely available, developed by the Japanese Amateur Radio League (JARL). However, the AMBE voice encoding scheme currently used by the DSTAR protocol is not open, rather it is patented by DVSI, Inc.

Development on an open source, freely available alternative to AMBE has been spearheaded by Australian amateur David Rowe, VK5DGR. This open voice codec is called Codec2, and is in a highly experimental stage at this current point. It’s advocates include Bruce Perens, K6BP, ( who is well known in open source software circles, and is a huge Free Software advocate.

What’s the issue with AMBE?

Codec2 developer David Rowe, VK5DGR talks about this on his blog:


“Due to patents and the amount of confidential information surrounding these codecs (AMBE) I don’t think it is possible to make an open codec compatible with these closed codecs. It is however possible to develop a open source, free-as-in-speech codec with similar performance at similar bit rates. […] A free codec helps a large amount of people and promotes development and innovation”


David Rowe’s development site is:

He is currently looking for assistance, either financially or with coding. Because of financial obligations, he’s currently on hiatus from development to pay bills with other work. Development milestones and source code are available through his website. David can be contacted at his email: David (at)

A DSTAR protocol implementing Codec2 Digital Voice would significantly drop the entrance level and appeal to a much wider audience. Once Codec2 is stable and competitive, it would offer a real, developed-by-a-ham alternative to the patented AMBE voice encoder.

If you are able to help with development please contact David Rowe!