On Sat, 11 May 2002, Paul Robertson wrote:
> Can I butt in with some basic questions?
> I'd just like to understand what kinds of applications will benefit from
> this proposal.
>
> We have lots of DVD players, the ubiquitous Brooktree framegrabber,
> and esoteric stuff like my ADV601.
>
> I know for sure it would help me.
>
> The Bt chips normally produce 25/30 interlaced frames/sec which might
> look lousy when displayed if there is horizontal motion.
> They can be programmed to decimate the frame, so you would only see say
> 25/30 even fields/sec
> Can they also be programmed to deliver 50/60 fields/sec?
> Does v4l support all this?
> Do v4l apps usually have the Bt chip writing the YUV image directly into
> video memory? Would Xv, or the graphics driver support odd/even fields
> in this case?
In that case, no. In the case of a decoder dumping data to
the graphics controller via the VIP (CCIR 656) it's possible and
I'm currently looking at implementing a generic CCIR656 input
device for the NVIDIA driver (for NVIDIA Personal Cinema and the
like). I will automatically bob the video in that case. No
API changes are required for that. You just tell the Xv adaptor
where to put the data and it will put anything coming through
the VIP port there. It relies on another piece of software to
program the device that sends stuff through the VIP, whether that
is a TV decoder, DVD card, or other device.
For cases where a Bt chip dumps YUV data to the framebuffer directly,
there are some synchronization issues that can't be solved unless
the Bt driver and overlay driver are the same driver. Currently,
with Xv+V4L based solutions, the Bt control is in the kernel while
the overlay is in the X-server. I don't see how to handle the
synchronization in that case.
>
> DVD players I know nothing about. What do they do?
>
Mpeg2 supports interleaved content. Looks like crap if you
display it as a weave. We're mostly talking about that on this
list. I think we merely need a standard XvPortAttribute hint
to tell the Xv adaptor if the next Xv(Shm)PutImage request
should be a field instead of the default frame behavior. The
Xv adaptor only loads half of the data in that case and
displays it with the correct offsets and scaling.
Mark.
_______________________________________________
Xpert mailing list
[EMAIL PROTECTED]
http://XFree86.Org/mailman/listinfo/xpert
