Hi folks, After experimenting with codec2 / fdmdv I realised that typical PC sound hardware is not FUN. I had a hard time finding a suitable soundcard / microphone combination that would yield a reasonable audio input for experimentation. I found that sampling the mic at 48ks and then downsampling with sox to 8ks yielded a much improved result. With this procedure I managed to produce something that after passing through the c2enc-mod-demod-c2dec chain was usable.
(those of you with better audio h/w might disagree :-) Noting that the initial sample rate should preferably be higher, I started thinking about how input sample resolution would affect the audio, and with an idea of using a MCU for transceiver interface, I decided to try codec2 out with 12 and 10 bit resolution. Not to interfere with the codec2 hacking, I wrote a small program that read in the raw input file for codec2, and masked it, removing the 4 or 6 least significant bits. Listening to the result, I could hear very little difference with a well adjusted audio file, (thanx peter). Next step was to pass the result through the codec2 chain, and the result is to my judgment very interesting, in that there is very little difference in the final recovered audio file. So, what do you think, this experiment is reproducible with only a small filter program, and maybe says something about possible future implementations. Regards, Gullik /SM6FBD ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
