Yes, you are right. To be precise the situation is as follows:
When the input buffer is full and the host controller switches to a new
buffer then there will be a USB frame in which you will not be polled.
At least this is true for the UHC.
So, I would recommend to use 2 ms or 4 ms polling interval.
Due to slight variations of audio clock and USB clock, you need to use a
larger FIFO size than 8 anyway.
Udo Eberhardt Thesycon GmbH
vrf wrote:
Transferring an audio stream by an interrupt pipe should be possible. However, it is somewhat "unusual". The priority of interrupt transfers is higher than bulk transfers. The host controller will poll an interrupt endpoint once per USB frame, if the polling interval is 1 ms.
I found that XP does *not* poll the interrupt endpoint always as requested by the polling interval bInterval member). Once in a while (2..10 secs) it skips a poll so you will be needing a larger outputbuffer (at least).
Bart ******************
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