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Re: How to Queue isoch read request

At 5:20 PM +0800 10/17/05, Gordon wrote: 

frameStart += 100;
for (int i = 0; i <4; i++)
{
    pipe->Read( frameStart, ... );
    frameStart += MAX_FRAME;
}

   But I can only get one error code: kIOReturnIsoTooNew
means that The isochronous I/O request is too early.So If
my way to queue isoch read request is wrong,what is the correct
way? Is there some sample like this for me?


Hi Gordon,

Either you didn't fill out the packet numbers in your buffers correctly or your request didn't get queued in time to go out the bus (but I thought that returned kIOReturnIsoTooOld -- it was kUSBNotSent2Err on Mac OS 9)

What I do when starting up an isochronous stream for reading it just queue reads starting and the current frame number and just respect to receive kIOReturnIsoTooOld packet errors until I catch up to the current frame number on the USB bus.

This has the advantage of starting as quickly as possible and always working, regardless of how long it takes the initial request to be queued.

HTH,

-Steve
--
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Steve Sisak, CTO                                 email@hidden
IOXperts, Inc.                                            +1 617 876-2572
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 >Re: How to Queue isoch read request (From: "Gordon" <email@hidden>)



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