Re: [pwc] Frame buffer underflow

[Andrew Cavers <>]

I've been having a similar problem with buffer underflow errors with
10.0.7a and 2.6.12 too. The camera works perfectly (apart from the
colour issues mentioned in another thread) using a program such as
mplayer to access the stream. However, when I try to access the device
using Puredata with the PDP plugin, I get the black screen/buffer
underflow errors.

I posted a message to the Puredata list regarding this issue (thinking
it was a PDP problem) and someone suggested I revert to the pwc/pwcx
drivers as they had also been having problems with the new drivers
from within PD. I'd rather not use the old drivers, but if it solves
the problem, it solves the problem! I'll report back once I've tried
that this evening.

Puredata seems to force the camera to run at 320x240 @ 27fps - this
seems to be at the very limit of what the USB bus can support -
perhaps this is the root of my problem?

Andrew.

On 7/5/05, Krzysztof Kowalczyk <> wrote:
> On Tue, Jul 05, 2005 at 01:12:18PM +0200, Luc Saillard wrote:
> > On Mon, Jul 04, 2005 at 02:01:34PM +0200, Krzysztof Kowalczyk wrote:
> > > Hi,
> > > I've tried philips pcvc680k with kernel 2.6.12.2
> > > and also with 2.6.12.2 with module compiled from pwc-10.0.7a.tar.bz2
> > > and I've got lots of messages:
> > >  kernel: pwc Frame buffer underflow (XXXX bytes); discarded.
> > > with XXXX depending on resolution.
> > >
> >
> > Can you try another application like xawtv ?
> I've checked with xawtv and got same problems, black image and lots of
> buffer underflow messages. But additionally I have some output from
> xawtv:
>
> This is xawtv-3.94, running on Linux/i686 (2.6.12.2n)
> /dev/video0 [v4l2]: no overlay support
> v4l-conf had some trouble, trying to continue anyway
> ioctl: VIDIOC_G_STD(std=0xb7f2643cbfc2ed20
> [PAL_D,PAL_M,PAL_Nc,PAL_60,NTSC_M_JP,?,?,SECAM_D,SECAM_L,?ATSC_8_VSB,ATSC_16_VSB,(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null)]):
> Invalid argument
> ioctl: VIDIOC_G_CTRL(id=9963778;value=134558539): Invalid argument
> ioctl: VIDIOC_S_CTRL(id=9963778;value=134558539): Invalid argument
> ioctl: VIDIOC_S_CTRL(id=9963776;value=64): Invalid argument
> ioctl: VIDIOC_S_CTRL(id=9963777;value=32): Invalid argument
> ioctl: VIDIOC_S_STD(std=0x0 []): Invalid argument
> v4l2: oops: select timeout
>
> > Do you have other usb device on the same bus ? perhaps it's the problem.
> I don't have any other usb devices connected right now.
>
> --
> Krzysztof Kowalczyk
>                                http://www.xysio.prv.pl/
>
> _______________________________________________
> pwc mailing list
> 
> http://lists.saillard.org/mailman/listinfo/pwc
>


--
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Andrew Cavers

www.mution.com
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