On Tue, Aug 19, 2014 at 2:39 PM, Daniel Mack <daniel@xxxxxxxxxx> wrote: > On 08/19/2014 11:01 AM, Jassi Brar wrote: >> On Tue, Aug 19, 2014 at 2:15 PM, Daniel Mack <daniel@xxxxxxxxxx> wrote: >>> On 08/19/2014 02:01 AM, Xuebing Wang wrote: >>> >>>>>> root@imx6slevk:~# >>>>>> root@imx6slevk:~# arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 >>>>>> Recording WAVE 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo >>>>>> Playing WAVE 'stdin' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo >>>>> Such a setup should work, I recently tried it myself. >>>>> >>>>> The other direction (capturing from host, playback on device), however, >>>>> has a major problem as the device interface has no timing mechanism, and >>>>> hence 'arecord | aplay' on the gadget side fails. I've prepared patches >>>>> and a more comprehensive description for this, but I'm waiting for >>>>> Andrzej's patches to be reviewed, as mine are based upon his. >>> >> Hmm... I tested 48KHz USB-IN without noise, 44.1KHz did show noise >> though ... iirc > > With USB-IN, you're referring to arecord on the host side, and aplay on > the gadget? Playing/ recording wave files on both sides worked fine for > me. The only problem here is that once you link one side to a sink or > source that expects audio to be transported at least roughly with the > announces sample rate, things break because there is nothing that > controls the timing. It's easy to fix, and as I said, I have patches for > this that I'll send out shortly. > Its been quite some time now, but I think we designed the uac2 to rely on USB's ISO packets' rate control to send and receive audio data at announced sampling rate. For some rates though the data rate doesn't become a multiple of packetsize and we see a periodic 'click' noise. Probably we are talking about the same thing. Please try to CC me on your patches. > However, I thought Xuebing's setup is the other way around, right? > Yes, Xuebing tested USB-OUT. Cheers, -Jassi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
