Am 17.04.2013 22:05, schrieb David Rowe: > Yes I think something like 800 bit/s is possible at roughly the same > quality using Vector Quantisation of the LSPs. However this wouldn't be > robust to channel errors. Well, I do intent to decrease bandwith in order to make it free for error-correction (Viterbi FEC 3/4 and 2/3). The goal is to keep ''payload'' (Voice and eventiually data, too) under 1200 bit/s...
(It's part of the cryptofon-project I'm on... At first, it is intended to work on 2400 bit/s, and carry vocoder, narrowband data transmissions and of cource sync data to enshure stable end-to-end communication..., including FEC in that bandwith! Codec 2 was the only solution that seemed practicable w/o licensing a propietary/patented codec, and there has already been an implementation on least-cost DSPs from TI's Stellaris family.) Vector Quatization seems pretty more predictable than an upper-level compression of the transmission, which does not seem to be capable to guarantee a fixed, low rate... But I'm not shure on that point, and may have to take a look on compression standards like V.42bis and algorithms such as Bzip2... There needs to be testing on how far this can go. I heard the record is 300 bit/s for a vocoder - but at poor quality. (Guess that's the cost of ultra-narrow-bandwith). But a 600 bit/s mode of Codec2 (or 800 bit/s as first step) would be a huge breaktrough, finally killing any arguments of propietary vocoders. ---Netzblockierer > > - DAvid > > On Wed, 2013-04-17 at 21:39 +0200, Netzblockierer wrote: >> Hi, >> >> just asking: Besides, as Codec2 is a Multiband-Exitation-Codec, I'm >> interested to know whether there can be even lower bandwiths achieved. >> Of course, this may increase encoder and decoder complexity, but when >> looking on ultra-narrowband - applilications, I only found a very few >> competitors: >> * TWELP (seems patent pending) >> * MELPe (Thales has patent on the 600 bit/s version. all higher >> bandwiths are partly patented by other companies, like TI, >> Microsoft, etc. ... The Thales patent has been granted in 2005 >> - so until 2030 it's out of reach...) >> * Two propietary encoders from DSP Innovators inc. - working >> with 600 and 800 bit/s >> http://dspini.com/index.php?com=page&sec=products, which are >> claimed patent-free and royality-free... >> >> I just read a while ago that there has been a testing on packet/frame >> loss... It resulted in two typed of bits... One called ''Wo_E'' or >> somelike that that are about 800 somewhat bit/s ... I suggested to try >> what happens if all bits except these are ''lost''/ignored... Has >> anyone tried it, and if, what are the results??? >> >> >> Greetings, >> Netzblockierer >> ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
