On Thu, 23 Jul 2015, Peter Chen wrote: > Assume the interval for each packet is 2ms, the rate is 192 kbytes > for both FS & HS: > uac2->p_interval = 2000; > uac2->p_pktsize = 192 kbytes / 2000 = 96 bytes It's important to keep track of the units. Intervals are measures of time, and they use units like seconds or microseconds. In this case, one packet gets sent every 2000 us, so the value is 2000 us/packet. The data rate is 192 KB/s. Let's agree to use units of microseconds and bytes. So converting from KB to bytes and seconds to microseconds, the data rate is: (192 KB/s) * (1000 bytes/KB) * (1/1000000 s/us) = (0.192 bytes/us). Therefore to compute the number of bytes per packet (the packet size), you have to _multiply_ the values -- not _divide_: (0.192 bytes/us) * (2000 us/packet) = (384 bytes/packet). Therefore the packet size should be 384 bytes, not 96. Alan Stern -- 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
