On Wed, Nov 21, 2001 at 11:50:57AM -0800, Mark Vojkovich wrote:
>This is an application bug. Apps are supposed to Grab the
> port when they want to use it so noone else can. When an app
> tries to grab the port and finds that it is already grabbed
> it will know that it is in use and it should fall back to some
> other method to display the video. When the apps do not grab
> the port they are using, continual preempting of each other's
> video is the expected behavior.
Hmm, does it really have to be like this? From my understanding of how
XvShmPutImage is implemented on most cards, there should be a way to implement
this reasonably:
- make sure when allocating offscreen memory for data that it doesn't overlap
- make sure when *CopyData422/420 are using DMA that only 1 DMA transfer
happens at a time (dunno, is this really necessary?)
- make sure calling *DisplayVideo422/420 only happens once at a time (from my
experience this takes an insignificant amount of time => chance that these 2
will overlap is low => can be ignored
So, in theory, making sure the allocated memory segments don't overlap should
be enough. As the CopyData422/420 takes almost all the time of the PutImage
function, there shouldn't be any strage slowdown besides lineary proportional
to the amount of data transferred (i.e. image size*depth).
Or am I missing something here (as usually )?
> Mark.
Bye,
Peter Surda (Shurdeek) <[EMAIL PROTECTED]>, ICQ 10236103, +436505122023
--
Give a man a fish and you feed him for a day;
teach him to use the Net and he won't bother you for weeks.
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