Re: WinXP USB BULK mode High speed

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what about a bigger transfer size per pended request? I have found that 2-3 pended requests will get all of the data off of the device, any more and you are really just burning memory w/out any benefit.

d

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"decoder" <rcg_golf@xxxxxxxxxxx> wrote in message news:eqLTmoxwHHA.2040@xxxxxxxxxxxxxxxxxxxxxxx
We have a scenario as follows using BULK mode:

- High speed USB device that provides MPEG2 TS. Device has 2K FIFO.
- Stream rate is approx. 32 Mbit/s, so we see an IN token in about 7000 out of the 8000 microframes per second.
- Our USB client driver is queuing up 8 requests, then requeueing 1 on Bulk complete, to make sure there is always a request ready for Host Controller.
- The driver is requesting 564 bytes( 3 * 188) at a time.

Problem:

- Some microframes come back to back from Host controller without an IN token
and we lose MPEG2 data from the device, since the device overflows its FIFO.

IS there anything we can do in our client driver to increase throughput?

Thanks
decoder


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