Hello Alberto, Long ago you sent the mail about resampling in Windows. I have not tested until today for various reasons.
The result is somewhat unexpected. I can see no difference whatsoever when running a Delta 44 at nominal 100 kHz. Neither performance nor cpu load is affected at all. The choice is available for Delta 44 multi on one of my Windows 2000 installations but not on the other. Presumably the drive routines from M-Audio differ. The two figures here http://www.sm5bsz.com/linuxdsp/install/uiparm.htm do truly represent the Windows performance and one should avoid non-integer resampling (silently) done by the Windows operating system. Another thing, Linrad now has a network by which one can split processing between several computers and also add various post-processors like MAP65 (hopefully) I have been able to do this for Linux only - using some prototype code for multicasting supplied by ON4IY and some code for a connected socket that I got from W3SZ. I think it would be nice to add network capabilities in the Windows version as well but I do not know how to proceed. Do you know where I can find some prototype code for receiving multi-cast under Windows ? (Data rates may be rather high so speed is essential.) 73 Leif > Leif Asbrink wrote: > > > > My concern is non-integer rate conversion. A soundcard > > that actually samples at 3.072 MHz and sends 48 kHz to > > the PC has to be down-sampled by 1.088435 times to > > produce 44.1 kHz. If it were properly done in the PC it > > would be perfectly OK, but judging from my experiment, > > the Windows device driver is not very accurate. > > > > My problem: How come that the computers do not ask > > "do you really want a rate conversion ?" when the user > > sets a speed that will cause a non-integer conversion? > > In Windows you can choose the compromise between quality of the resampling > and resources utilized for that. > Click on Control Panel | Sound and Audio Devices | Audio | Advanced | > Performance and in the bottom part of the panel > you are now in, you will find a slider labeled "Sample rate conversion > quality". It is advisable to keep it at its > extreme right, the best quality. > > Anyway in Winrad I coded a non-integer resampling routine using the method of > interpolation on a windowed sinc. The > results seems to be quite good, the spurs generated by the resampling are > usually between -90 and -100 dBc (if I recall > correctly). I wonder which algorithm does use Windows. The interpolation is > quite fast, the CPU used is minimal. > > 73 Alberto I2PHD > > > ############################################################# > This message is sent to you because you are subscribed to > the mailing list <linrad@antennspecialisten.se>. > To unsubscribe, E-mail to: <[EMAIL PROTECTED]> > To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> > To switch to the INDEX mode, E-mail to <[EMAIL PROTECTED]> > Send administrative queries to <[EMAIL PROTECTED]> > ############################################################# This message is sent to you because you are subscribed to the mailing list <linrad@antennspecialisten.se>. To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> To switch to the INDEX mode, E-mail to <[EMAIL PROTECTED]> Send administrative queries to <[EMAIL PROTECTED]>
