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Date:      Mon, 02 Mar 1998 03:09:16 -0800
From:      Amancio Hasty <hasty@rah.star-gate.com>
To:        Luigi Rizzo <luigi@labinfo.iet.unipi.it>
Cc:        multimedia@FreeBSD.ORG, james@miller.cs.uwm.edu
Subject:   Re: Video ioctl interface 
Message-ID:  <199803021109.DAA10048@rah.star-gate.com>
In-Reply-To: Your message of "Mon, 02 Mar 1998 10:24:09 %2B0100." <199803020924.KAA20469@labinfo.iet.unipi.it> 

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We should be able to do something along those lines and please
bear in mind that we do have hardware clip assist which is the
inverse of what you are proposing. 

Additionally,for the general case it will involved the driver copying
the image to the user buffer and then to the X server.

For the case of another card , we already do that and thats the
PCI to PCI mode which is accomplished by specifying the virtual
memory of the start of the memory mapped device which typically
an X application does not have access to.

	Amancio




> > I think that we are now at good point to change the interface so 
> > what I would like to see is proposals or ideas for the new interface.
> 
> a random idea i have had in mind for some time is to make the frame
> buffer read/write, and allow the card's output to be mapped anywhere
> in the buffer (possibly even the one of a different card), not just
> at the upper left corner.
> 
> This would be done to allow nice picture-in-picture effects, e.g. one
> application could write a slide (or something similar) into the frame
> buffer while the Bt848 shows live video in a portion:
> 
>    .............................    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx   
>    .............................    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx   
>    ....  application output ....    xxxxxxxxxxxxxx..appl....xxxxx
>    .............................    xxxxxxxxxxxxxx..output..xxxxx
>    .............................    xxxxxxxxxxxxxx..........xxxxx
>    .............................    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>    ..................xxxxxxxxx..    xxxxx live video xxxxxxxxxxxx
>    ..................x video x..    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>    ..................xxxxxxxxx..    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>    .............................    xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> 
> the advantage would be that fxtv, vic&friends could just read from
> the driver rather than mess up with mixing windows etc.
> 
> 	cheers
> 	luigi
> -----------------------------+--------------------------------------
> Luigi Rizzo                  |  Dip. di Ingegneria dell'Informazione
> email: luigi@iet.unipi.it    |  Universita' di Pisa
> tel: +39-50-568533           |  via Diotisalvi 2, 56126 PISA (Italy)
> fax: +39-50-568522           |  http://www.iet.unipi.it/~luigi/
> _____________________________|______________________________________



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