[GEM-dev] Re: [PD] pix_video not working in Linux

[IOhannes zmoelnig]

Mirko Petrovich wrote:
> Hi all

hi mirko. hi gem-devs.

this reply is partly meant for the gem-dev's, so don't be scared of 
weird explanations...

> 
> I downloaded GEM from cvs (2003-11-15) and pix_video doesn't work for my 
> saa7134 (V4L2) capture-card. IIRC it worked well in some 0.87 cvs 
> snapshots, and after that (0.87 release) it never worked again for more 
> than 10 seconds. When using pix_video I get a lot of *GEM: pix_video: do 
> video for this OS* in the console and messages doesn't work :
> 
> error: pix_video: no method for 'channel'
> error: pix_video: no method for 'mode'
> error: pix_video: no method for 'norm'

this basically means, that you are using the parent-class of [pix_video] 
instead of [pix_videoLinux] or [pix_videoNEW]

i guess, this is due to the automatic registering code (the pix_video 
class registering itself before the proper implementation class to pd)

i have committed some changes to the CVS that make this more managable:
if NO_AUTO_REGISTER_CLASS is defined before the CPPExtern.h is included, 
then the registering code is omitted.

> 
> When using pix_videoLinux with pix_rgba (because I get *error: Gem: pix 
> object cannot handle RGB image*)  I get the following:

so with the new cvs-code, you should be able to use [pix_video] instead 
of [pix_videoLinux] resp. [pix_videoNEW].

> but no image , only a white rectangle.
> I tried sending the following messages : channel 2, norm NTSC, mode NTSC 
> 2 , driver 0 , device 0 also I tried pix_videoNEW but still no image. 

on linux you should rather use [pix_videoNEW], because i submit all my 
changes to this rather than [pix_videoLinux].
anyhow, this doesn't make it work.

i have had this problem once on a quickcam attached to a gericom-laptop 
(not mine)
for further investigation i took the camera home, plugged it into my 
workstation and it worked like a charm (with Gem).
so i thought it was gericom-crap...

just a guess: the image is captured correctly but it is not textured. 
([pix_draw] might produce the same result)
for validation try to use [pix_pix2sig~] and [pix_sig2pix~] to transform 
the captured image into signal-space and back again. do you see anything 
but white  (might be not very satisfactory) ? (don't forget to turn the 
audio-engine on...)

if so, what could it be ?
a) your gfx-card
b) the [pix_texture] code

which gfx-card are you using (driver) ?
system-specs (kernel, distribution (is it gentoo ?),...)

mfg,.as.dr
IOhannes