Borislav Trifonov wrote: > The USB Audio standard uses isochronous transfer in one of three modes: > synchronous, adaptive, or asynchronous. I'm developing hardware that > will use the asynchronous mode to communicate with the PC, so that it is > the one doing flow control. > > My question stems from something someone told me about Windows, that it > actually will resample the data if asynchronous mode is used, which is > bad and not in the spirit of the standard specification. So I want to > confirm that Linux will _not_ do that when asynchronous USB Audio is > used, and the data will be bit-perfect -- the PCM data the player > application sends to the system is exactly what comes out the USB port.
snd-usb-audio never resamples. The driver reports the actual sample rate (as reported in the async feedback packets, and measured relative to the USB clock) in /proc/asound/card*/stream*, but this is just for debugging purposes. The sample rate that is queried/set by user space is always assumed to be measured by the device's own clock. HTH Clemens ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
