Hello, I have just checked in some updates to the code that implements the various bit rates. The rates are now a more standard 2400/1400/1200 and 1200 has been improved a little bit by using a 27 bit VQ.
I have updated 2400/1400/1200 the samples on the Codec 2 web site to match the latest code. Thanks Jean-Marc for your joint pitch and energy VQ - I have used that on all rates now. Actually 2400 has two spare bits so its really 2300 and 1200 even has one spare bit so it's actually 1175. With a few tweaks I think 1000 bit/s is possible - if any one wants to work on that let me know and I will give you some tips. Its fairly straight forward, not much DSP required. I have been experimenting with some files that don't work too well on the codec and have noticed files with a lot of low frequency (like those samples from a PC microphone) don't get quantised too well. So I am considering adding a high pass filter Although the low frequencies sound nice, they don't add to the intelligibility, so we are better off applying our precious bits to those frequencies above 300 Hz. Also in a digital radio application, we may be using a small speaker, so the energy beneath 300 Hz won't be reproduced anyway. Any thoughts on high pass filtering? Thanks, David ------------------------------------------------------------------------------ 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
