Hi David Let us clarify this point a bit more...
I have not changed anything in my code from 700b to 700c. Just switching the sharable library codec2.so after building it from the SVN. In 700b-Implementation, I make the downsampling by myself in my code (I use SVN-Version 2299 for 700b). I use the following steps: 1) downsampling my 48000S/s to 8000S/s for freedv_tx 2) freedv_tx(...) // using 7500S/s-Data 3) upsampling to my tx-Datarate of 48000S/s. In 700b-Demodulation: 1) downsampling 48000S/s to 7500S/s 2) freedv_nin(...) // to get count to work with 3) freedv_floatrx(...) 4) upsamling to my rx-Datarate 48000S/s On both sides, there is quite some buffer management involved, because of the 7500 to 48000 ratio. As far as I understand your statement, this code won't work with SVN-Version 2998 for mode 700c. When making 700c-experiments with the code above, I hear hickups in the demodulated audio. Greetings, Alfred On 29.01.2017 23:05, David Rowe wrote: > Hi Alfred, > > Internally the modem side of the 700 modes run at Fs=7500 Hz due to the > design of the waveform for the coherent PSK modem. However in 2015 Jim > Ahlstrom kindly added a resampler to the FreeDV API so the 700 modes now > all have an Fs=8000 Hz interface. > > If you call the cohpsk modem functions directly then Fs=7500Hz is required. > > Cheers, > > David > > On 30/01/17 07:14, wully wrote: > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
