Mailing Lists: Apple Mailing Lists
Image of Mac OS face in stamp
 
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: TimeStamps with ischo. transfers

At 03:12 AM 10/21/2005, Niels wrote:
Hi Devendra

When your update runs, the timestamp is copied out of the hardware program into your time stamp buffer.

Aha! Perhaps this is where the problem lies with isoch. sends.

For isoch. sends, the "update" has to run "before" the packet is sent, correct?

[At least that's what the requirement was with legacy DCLs]

In that case, the timestamp that is copied to our time stamp buffer is actually invalid, or perhaps "stale". Because up to that time(when the update is run), the data has not even been sent, so how could it know what time it will be sent!

When you call notify( kFWNuDCLModifyNotification ), the hardware descriptors for the affected DCLs will be rewritten... your timestamps on the recompiled DCL may no longer be valid, so inspect them before calling notify().

Yes! I do inspect them before calling notify()! But it's good to know that it's a requirement!

Does that help?

Yes. I think this explanation (with the update running before the data is sent) matches my observations.

Thanks.
Devendra.
 _______________________________________________
Do not post admin requests to the list. They will be ignored.
Firewire mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/firewire/email@hidden

This email sent to email@hidden
References: 
 >listen DCL program woes (From: Philip Lukidis <email@hidden>)
 >TimeStamps with ischo. transfers (From: BlazeAudio Developer <email@hidden>)
 >Re: TimeStamps with ischo. transfers (From: BlazeAudio Developer <email@hidden>)
 >Re: TimeStamps with ischo. transfers (From: Niels <email@hidden>)



Visit the Apple Store online or at retail locations.
1-800-MY-APPLE

Contact Apple | Terms of Use | Privacy Policy

Copyright © 2007 Apple Inc. All rights reserved.