Am Freitag, 15. Oktober 2010, 15:31:50 schrieb Alex Lee: > On Fri, 2010-10-15 at 15:04 +0200, Julian Scheel wrote: > > Ah right, thanks. > > Well now I swapped data[1] and data[2]. When monitoring the amount of > > data I get per read, it is constant at 192bytes, which would be expected > > for feedback ratio of 48, right? But if I have 0x06 to 0x07 for example > > I do still get exactly 192bytes per read, shouldn't I get less data in > > that case? (I always try to read up to MAXPACKETSIZE which is 512, btw) > > Suggest: > > (1) The feedback rate has to fall withing +/- 10% of the nominal rate. > Otherwise it is ignored. Ok. I tried it with 0x5e, which should be 47. Still same amount of data being fed in. > (2) You need to find out exactly how many samples the host sends you. > Look at my sdr-widget code, for example. Then you read what the host > sends you. Actually I checked your code and it seems quite similiar to mine. I use the at91lib for USB stuff, so the capsulation is a bit different. I call a function USBD_Read, which does read up to the given amount of bytes (in my case max 512) or the receivement of a short packet. Each packet I receive by reading with USBD_Read is exactly 192bytes long. As I won't be able to get more than 1 packet per USB frame, I should be receiving 1000 * 192bytes per second. No matter what I write to the feedback pipe. which is kinda odd. > (3) Do a > dmesg | tail > after unplugging and plugging your USB device in. Then you can see > whether there are any errors in your syncpipe Don't see any syncpipe related errors. Only thing I see is: usb 1-1.3: new full speed USB device using ehci_hcd and address 11 11:1:1: endpoint lacks sample rate attribute bit, cannot set. 11:1:1: endpoint lacks sample rate attribute bit, cannot set. Does not seem to be feedback related... Although it would be nice to know, what's wrong there? > btw, what is your Linux kernel version? 2.6.35.7-1 (archlinux, 32bit) Is there any way to get some more verbosity out of alsa drivers? To check if it really receives the feedback information at all. Regards, Julian _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
