X, Network transparency and ssh

[Peter]

On Fri, 13 Jan 2006, Robert Brockway wrote:

> On Fri, 13 Jan 2006, Lennart Sorensen wrote:
>
>> Xvideo, Xshm and DGA and other such features are very handy for
>> displaying large amounts of graphics very quickly and efficiently.
>> Remote displays can't do any of them, and hence it makes perfect sense
>> to not bother implementing any such things.  Running a compressed video
>
> This certainly seems to be his position.  I don't agree that the suboptimal 
> nature of a remote display of TV is sufficient reason not to implement the 
> features once the core feature base is solid (which it is in the case of 
> tvtime).  I'd rather tvtime allow it to happen, perhaps with a warning.  Of 
> course this is OSS so a code fork is always an option :)

This is a hardware issue. The way direct X11 (aka overlay - hehe) works 
with xawtv is, the RISC cpu in the tv capture card is programmed to 
write data directly into the screen buffer, using the PCI bus. The CPU 
is not involved. That's why it's fast. For obvious reasons, you can't do 
this over the network.

X11 is not fast enough for live video at 50fps and full screen with 
substandard hardware (like I and many others use - i.e. sub 1G cpus), 
but the real bottleneck is the network. Do some calculations, yourself. 
16bpp with 750x350x50fps*2bytes/pixel = 26Mbytes/sec or twice as fast as 
the maximum throughput of 100MBps network, run peer to peer under 
optimal conditions.

If you run a live encoder and watch the resulting ogg or avi or mpeg 
through the network with xine, f.ex., then you have better chances to 
make this work.

Peter
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