On 11/05/2012 10:46, Peter wrote: > On 11 May 2012 10:37, Ed W<li...@wildgooses.com> wrote: >> Beware that the AC97 codec (ie any internal sound card from a few years >> back or older) almost exclusively runs at 48Khz and will only work >> reliably at that rate. To convert to any other frequency there will >> usually be an absolutely awful resampler implementation which will cause >> all kinds of wierd (nonlinear) artifacts. As such for anything >> requiring even reasonable fidelity and a built-in soundcard, first check >> the specs, but then if in doubt run at 48Khz and use your own resampler >> to get the frequency you want. > Hi Ed, > > The actual sound card I use for radio use is the "Startech 7.1 USB > audio". It's fairly cheap and cheerful, but not the most cheapest and > cheerful. I have also a Soundblaster Audigy PCI card. But, it's not > practical to hook it up to the radio (the 3.5m cables are too short). > The USB solution is just a general easy solution for me. I have the > CI-V, and PTT controllers as USB (prolific controllers) and the sound > as a USB card, all plugged into one USB hub. So I can then just > present one USB cable to my PC and everything springs into life. > > I'll go to 48k using the highest quality mode in cooledit and > hopefully that's be the safest route to take. >
The problems with non 48Khz rates are quite extreme where they occur. Just record something above your nyquist and examine the output in cooledit. If it is full of aliased junk then you have a problem. Otherwise probably the card has hardware clocks allowing it to sample at other frequencies and all should be well. As I understand it the issue with AC97 codecs are that they literally only work at 48Khz and everything gets resampled (badly) to that freq Regards Ed W ------------------------------------------------------------------------------ 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 Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
