On Thu, 31 Aug 2006, Lee Revell wrote: > On Thu, 2006-08-31 at 12:45 -0700, Bill Unruh wrote: >> I have a fairly stringent sound card test >> (www.theory.physics.ubc.ca/soundcard/soundcard.html) >> that you can try out. The sound card has to be capable of input and >> output >> at the same time since it feeds theoutput to the input, and thus tests >> both >> at once. >> Although it is designed for the now outdated OSS, it can be used with >> ALSA >> with a bit of effort. > > Does you tester make sure to test at a hardware-supported sample rate? > Otherwise you could be testing the quality of the in-kernel OSS > emulation's software resampler...
It is up to you-- ie you can ask either for 44100 or 48000 as the only two choices. However, under alsa, you can aplay a file included with the program and arecord that sample fed back through the soundcard and then use the program to analyse that recorded file. It feeds "pink noise"-- actually 7 frequencies per octave for as many octaves as you want through the soundcard, subtracts out those frequencies and looks at the remaining noise. This gives a measure of all of IM, Harmonic distortions, as well as noise from the card, with a signal which is much more similar to true recorded material than the single frequency stuff of most distortion analyses. For example, the Transit is about 3dB above 16 bit quantisation noise across the band with a signal which is at the max amplitude the card can handle and with a very flat response (10 octave "pink noise" signal.) > > Lee > -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | [EMAIL PROTECTED] Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
