Codec 2 at 3200 bit/s

For the last few weeks I have been working on integrating the new LPC post filter into Codec 2 as part of some paid Codec 2 work to develop higher quality, higher bit rate modes for VOIP. Although I actually had a budget of up to 6400 bit/s, much to my embarrasment I couldn’t work out a way to effectively use more than 3200 bit/s!

Anyway I am quite happy with the quality improvement, and the new 3200 bit/s mode. See what you think:

Previous Codec 2 2400 bit/s New Codec 2 2400 bit/s Codec 2 3200 bit/s AMR-NB 4750 bit/s 8000 bit/s Codec
hts1a hts1a hts1a hts1a hts1a (g729)
hts2a hts2a hts2a hts2a hts2a (g729)
mmt1 mmt1 mmt1 mmt1 mmt1 (Speex)
morig morig morig morig morig (Speex)

See the Codec 2 page for some other samples.

I think Codec 2 at 3200 bit/s holds up OK next to AMR-NB at 4750 bit/s. AMR is a heavily patented, license encumbered Codec, running at a 50% higher bit rate, which was developed with the resources of several multi-national corporations. According to the Wikipedia page you need to pay $6,500 for a license, then a minimum of $10,000 a year in royalties.

More quality improvements to Codec 2 are possible in future. I am not a multi-national corporation, just some guy hacking on a kitchen table. Now I better go and make dinner!

3 comments to Codec 2 at 3200 bit/s

  • Smartass

    Does it work well for Chinese etc.? During Opus development, this question came up and testing was conducted. (I’m not Chinese, btw). If not, you can spend the bitrate there :) Or thy spending the bitrate on wideband

  • John

    I wonder if a cheap box, raspi or max32 could be programmed to be a codec tester combined with an HF transceiver? We could all join the net and try it out over the air?

    Processors are now fast enough to do 40m, 30m or 20m in native code especially with FPGA support :) .

    Sounds like a cool project to me!

    John

  • Hi David,
    I saw a message about someone violating FreePBX’s GPL code: http://permalink.gmane.org/gmane.law.gpl.violations.legal/4316

    Then I started to search more about this subject and discovered your site.
    It is nice to know you develops some telephone related open-source hardware, but my biggested surprise was to know you are the author of code2 codec.

    Thanks for doing these great works!

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