Thanks Bruce. I haven't actually checked the code for 2100 bps yet, still tweaking, so difficult to test on air at present. Once we have something at a usable bit rate, I'll look into fixed point porting so we can get it to run on smaller CPUs.
- David On Fri, 2011-10-28 at 09:03 -0300, Bruce Robertson wrote: > Sounds great, David. Well done! Time to fire up another test run, perhaps? > > I now have an android nexus s phone with a 1 GHz Hummingbird > processor. I'd love to get C2 running on that using the NDK. I'd also > like to get a 2m link working, but packet -> TCP or UDP entailed way > too much (and too unpredicatable) overhead for me last year when I > played around with it. > > 73, Bruce > VE9QRP > > On Fri, Oct 28, 2011 at 12:30 AM, David Rowe <[email protected]> wrote: > > Hello, > > > > I am back developing Codec 2 again. > > > > 1/ I have been working on line spectrum pair (LSP) quantisers, and have > > attached some samples from a 2500 bit/s and 2100 bit/s version. > > > > The 2500 bit/s version uses 4,4,4,4,3,3,3,3,3,2 bit scalar LSP quantiser > > (36 bit/fr). > > > > The 2100 bit/s version uses scalar quantisers of 4,4,4,4 bits for the > > first 4 LSPs, than a 12 bit (4096 entry) VQ for the last 6 LSPs (28 > > bits/frame). > > > > They sound fairly similar to me, what do you think? > > > > 2/ While playing with LSPs I found that "quantising" LSPs 1 to 10 to > > 25,25,50,50,100,100,100,100,100,100 Hz steps has no effect on speech > > quality. In other words an error of +/- 50Hz in say LSP 10 (or +/- > > 12.5Hz in LSP 1) can't be heard. > > > > This is a little like bandwidth expansion of LSPs, or "just noticeable > > differences". > > > > I am wondering if this effect can be used in quantiser design or vector > > codebook searching as a metric for how perceptually "close" two > > candidate vectors are to the target. Or we could discard entries in a > > VQ during training that are close enough to be perceptually > > indistinguishable. > > > > Another idea is to use this effect in coding frame-frame differences. > > During perceptually important strongly voiced speech LSPs change slowly. > > Changes that are not perceptually noticeable don't need to be quantised > > and transmitted. > > > > So if we take a frame-frame deltas of LSPs e.g. > > 25,-25,25,25,25,25,25,25,25,25 then set changes smaller than the limits > > above to zero we might have a perceptually-equivalent frame-frame delta > > of 25,-25,0,0,0,0,0,0,0,0. Presumably this would take less bit's to > > encode. > > > > Cheers, > > > > David > > > > > > > > > > > > ------------------------------------------------------------------------------ > > The demand for IT networking professionals continues to grow, and the > > demand for specialized networking skills is growing even more rapidly. > > Take a complimentary Learning@Cisco Self-Assessment and learn > > about Cisco certifications, training, and career opportunities. > > http://p.sf.net/sfu/cisco-dev2dev > > _______________________________________________ > > Freetel-codec2 mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > > > > ------------------------------------------------------------------------------ Get your Android app more play: Bring it to the BlackBerry PlayBook in minutes. BlackBerry App World™ now supports Android™ Apps for the BlackBerry® PlayBook™. Discover just how easy and simple it is! http://p.sf.net/sfu/android-dev2dev _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
