Hi Michael,
Thanks for the post - very interesting. Sure is an exciting time for
speech coding.
The speech quality of Lyra is vastly better than anything Codec 2 can
offer at a similar bit rate (3000 bits/s). Codec 2 would sound closer
to the Speex 3 kbit/s samples on the Lyra page. Lyra has reasonable CPU
complexity (single thread of a modern smartphone), but that's still much
higher than Codec 2 (which runs on microcontrollers). Lyra presently has
no low bit rates modes (Codec 2 is commonly used at 700 bits/ for HF
radio applications). Codec 2 is open source and GPL Licensed. I'm not
clear where Lyra stands on those issues. The latency of Lyra appears
quite high (90ms).
Lyra is a Machine Learning (ML) based codec, so in a similar class to
Jean-Marc Valin's LPCNet, which is open source. Our initial attempt with
using LPCNet in real world scenarios (e.g. FreeDV 2020 for HF radio)
shows a lot of promise, but has some speaker dependence and possibly
quantisation issues (it breaks down on some speakers - sounds great on
others). The Lyra team claim to have put a lot of work into
speaker-independence, and the project has a lot of resources behind it :-)
Codec 2 presently has one very part-time person working on the core
speech codec and several other people kindly contributing to other parts
of Codec 2/FreeDV :-)
At 3kbit/s Lyra would fit neatly into VHF/UHF radio type applications,
that would be a cool demo.
Cheers,
David
On 28/2/21 4:50 am, mgraves mstvp.com wrote:
Hi,
While I’ve watched from afar, this is my first message to this list.
I was wondering how Codec 2 compares to this latest effort from
Google; Lyra.
https://ai.googleblog.com/2021/02/lyra-new-very-low-bitrate-codec-for.html?m=1
Michael Graves
mgra...@mstvp.com <mailto:mgra...@mstvp.com>
o: (713) 861-4005
c: (713) 201-1262
sip:mgra...@mjg.onsip.com
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