[vdr] Re: XServer (was: Games & etc on DVB)

[ma.hoff@t-online.de (Martin Hoffmann)]

Yes indeed !

However we're talking about games & etc (see subject) - so maybe video ? And 
this means changing the whole screen 25 times per second !

So, youre right in case we want to show a desktop or sth, but not for gaming 
and video ...

Here's my 10 cents my 2 cents is free ;-)

Martin

> Hi,
>
> I agree with you, applications that need to transfer uncompressed image
> data in real time are not possible with the dvb-card. But this is
> different in the case of an X-Server. There is no need to transfer the
> complete frame buffer each time the image changes. Instead it's enough
> to transfer the rectangle containing the changed area and write it to a
> specific location of the dvb-cards framebuffer (in 8k chunks).
>
> just my two cents,
>
> Matthias
>
> Matthias Mueller wrote:
> >Hi,
> >
> >On Thu, Sep 19, 2002 at 06:15:54PM +0200, Martin Hoffmann wrote:
> >>>It would be too slow. Why not write driectly into the framebuffer of the
> >>>dvb-card??
> >>
> >>Of course yes - but afaik the current driver (or maybe the hardware
> >> itself) does not allow to directly acces the buffer of the card !
> >
> >According to a mail to the dvb-mailinglist, it's not possible:
> >>Peter Seyringer writes:
> >>>Is it posible with the new firmware to write direct in the framebuffer
> >>>memory of the mpeg encoder. This would be a great future to implement
> >>>some programs without any complicat algols (like converting them into
> >>>MPEG1 oder MPEG2). That makes it also posible to implement a WEB browser
> >>>oder same games on the dvb-s card :).
> >>
> >>No, sorry, nothing regarding this was improved in the new firmware.
> >>
> >>You are talking about 720x576x2x25 or about 20 MByte/s which
> >>you would need for transfering complete pictures in real-time.
> >>I don't know how high we could really get. Right now we are happy
> >>about 20 MBit/s.
> >>It would also create over 5000 Interrupt/s on the PC side even
> >>if you use the full 8K dual ported RAM with buffer switching
> >>for transfers.
> >>
> >>Ralp
> >
> >Even if you could use 352x288, that would still need ~40MBit/s. I don't
> >think this will be possible...
> >
> >Ciao,
> >Matthias