[PD] PDP Webcam problem

[Andrew Cavers]

List,

I'm having a peculiar problem accessing my webcam within PD using PDP.
The camera works fine outwith PD (using mplayer, for example). My
camera is a Logitech Quickcam Pro 4000 and I'm running PDP 0.12.2
(from the sourceforge CVS - I had the same problem with 0.13), PD
0.38-4 and the most recent pwc driver (10.0.7a) on a 2.6.12 kernel.

The symptoms: as soon as I try to open the device from within PD and
send the output to pdp_xv, top says PD is using 60% of the cpu, an xv
window is created but is black. I get the following message in the PD
window:

pdp_xvideo: grabbed port 64 on adaptor 0
pdp_v4l: no device opened
pdp_v4l: attempting auto open
pdp_v4l: opening /dev/video0
pdp_v4l: cap: name Logitech QuickCam Pro 4000 type 1 channels 1 maxw
640 maxh 480 minw 160 minh 120
pdp_v4l: picture: brightness 36864 depth 24 palette 15
pdp_v4l: channel 0 name Webcam type 2 flags 0
pdp_v4l: switched to channel 0
pdp_v4l: buffer size 925696, frames 2, offset 0 462848
pdp_v4l: using VIDEO_PALETTE_YUV420P
pdp_v4l: frame 0 0, format 15, width 320, height 240
pdp_v4l: Opened video connection (320x240)
pdp_v4l: detected pwc
pdp_v4l: camera framerate set to 27 fps

This all looks pretty good does it not?! PD CPU usage stays at 60%
until I quit the patch. When I use mplayer to access the device at the
same resolution and fps (320x240 @ 27fps), it uses about the same
amount of CPU. (I'm using a 600mhz machine).

But, dmesg shows that my webcam driver was giving the following output:

pwc set_video_mode(320x240 @ 27, palette 15).
pwc decode_size = 3.
pwc Using alternate setting 6.
pwc frame_size=31800, vframes=27, vsize=3, vsnapshot=0, vbandlength=530
pwc Frame buffer underflow (31808 bytes); discarded.
pwc Frame buffer underflow (4 bytes); discarded.
pwc Frame buffer underflow (29692 bytes); discarded.
pwc Frame buffer underflow (15520 bytes); discarded.
pwc Frame buffer underflow (31808 bytes); discarded.
pwc Frame buffer underflow (4 bytes); discarded.
...
[and so on while the patch is running, I guess]
...
pwc Frame buffer underflow (16205 bytes); discarded.
pwc Closing video device: 2424 frames received, dumped 0 frames, 180
frames with errors.

I don't get these errors when accessing the device using mplayer.

So - I think the problem lies with pdp_xv. It outputs video from
pdp_noise fine, but only if I have not yet tried to output pdp_v4l in
that session. pdp_glx, does produce output from the camera but
increases my cpu usage to 100% and makes the system extremely
unresponsive.

Any ideas?! I hope that this is enough information for someone to have
an idea about what's going wrong. Any help would be much appreciated!

Cheers,

Andrew.

--
Andrew Cavers
andy at mution.com
www.mution.com