[PD] pix_video metro

IOhannes m zmoelnig zmoelnig at iem.at
Mon Jan 10 20:33:55 CET 2005

sara kolster wrote:
> Hi all,
> I'm trying to figure something out [again] with pix_video. How does the 
> playback from pix_video work and can I influence the playback with a 
> different metro?
> Right now, I've a webcam connected and the playback seems to be a little 
> slow and a bit blurry; I just want to try what I can do to change speed 
> of the playback, but cannot find anything in the helpfile of pix_video.
> I tried to connect a metro [40] to pix_video but that doesn't work.

this seems to be complicated...

[pix_video] captures the input-stream of a capture-device; as capturing 
is done in real-time you cannot speed [pix_video] up (at least not in 
our space-time-continuum where we cannot travel into future)

however, if you think that the latency is to high (the time between you 
waving before the lens and the movement appearing on the screen) read on

connecting [metro 40] to [pix_video] is an interesting idea, but 
unfortunately this is not the way it works.
gem builds its own "render-clock", which you cannot speed up (or change 
at all!) with a [metro].
if you want higher frame-rates, you can send a "rate" message to the 
[gemwin], like [rate 60( (the default of 20 is a bit low); you can even 
set the default frame-rate as an argument to [gemwin] (like [gemwin 60])

because you had the idea of using [metro] i guess you have used pdp 
before, and thus are on linux (or rather os-X, as your mail-client seems 
to imply)

as for linux: gem captures from the video-input as fast as possible in a 
separate thread; this should make videoIN as smooth as possible; 
however, the captured images are displayed only once a render-cycle, so 
  incrementing the framerate (see above) might help (a bit)

as for osX: in theory it should be very similar, except that jamie and 
chris have done huge accelerations, so it should be even faster.
otoh, osX-users tend to use USB or ieee1394 cameras which have a very 
high latency (read: it takes a long time from the image to be "shot" 
until it appears on the screen); this is due to the hardware-limitations 
of ieee1394/usb; you (and me neither) cannot do anything about it

do you know of any application that captures _way_ faster with the same 
hardware ?? (would be interesting to know)


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