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Patent Free low-bitrate codecs?

Started by gl January 4, 2001

I'm just starting to get involved in speech processing/coding, and I'm
trying to find low-bitrate patent-free codecs, around 4.8kbit and below.

I haven't been able to find any solid info on patent issues with some of the
obvious codecs (eg. CELP). For example, CELP is standardised by the US DOD,
and they supply free source code - does this mean that basic CELP is free,
even for commercial use? Are all standardised codecs free by definition?
Is there a good resource listing speech codec patent status?

I'm also more generally interested in LPC speech coding/analysis. Is LPC
itself patented? (I hope not).
--
gl