Hi Jon,

On Thursday 23 July 2009 10:15:19 Jon Fairbairn wrote:
> Laurent Pinchart <[email protected]> writes:
> > Hi Jon,
> >
> > On Tuesday 02 June 2009 19:34:55 Jon Fairbairn wrote:
> >> Laurent Pinchart <[email protected]> writes:
> >> > I would still be interested in messages printed by the
> >> > uvcvideo driver in the kernel log when running motion.
> >>
> >> With trace=15, there's quite a lot. I've removed what I think
> >> is boring, but let me know if I've trimmed too much:
>
> [...]
>
> >> Enabling workaround. [ the next section repeats continually while motion
> >> is running ]
> >> uvcvideo: Trying format 0x47504a4d (MJPG): 352x288.
> >> uvcvideo: Using default frame interval 33333.3 us (30.0 fps).
> >> uvcvideo: Trying format 0x47504a4d (MJPG): 352x288.
> >> uvcvideo: Using default frame interval 33333.3 us (30.0 fps).
> >> uvcvideo: Setting jpeg quality to 100.
> >> uvcvideo: Control 0x0098090e not found.
> >> uvcvideo: Control 0x0098090f not found.
> >> uvcvideo: Control 0x00980911 not found.
> >> uvcvideo: Control 0x00980912 not found.
> >> uvcvideo: Control 0x00980913 not found.
> >> uvcvideo: Control 0x08000000 not found.
> >> uvcvideo: Control 0x08000001 not found.
> >> uvcvideo: device Live! Cam Optia requested null bandwidth, defaulting to
> >> lowest.
> >
> > The problem might be in motion then.
>
> It turns out that the problem is that the Creative Live! Cam Optia can't
> drive 4.8m of cable properly (even though that's less than the spec),
> and drops/corrupts frames. Then motion is rather too intolerant of bad
> frames. With no extension lead or a hub (even bus-powered) in the line,
> the problem disappears.
>
> >> > > mplayer with -tv mjpeg
> >> >
> >> > It might still be using MJPEG, although this sounds a bit
> >> > weird.
> >>
> >> It doesn't look like it...
> >
> > And there might be a problem in mplayer as well.
>
> That seems likely. If I have time I'll report that. In the meantime, I
> reckon the JPEGCOMP support is working. Can it go into the released
> version, please?

Unfortunately, no.

According to V4L2 developers (see this thread 
http://thread.gmane.org/gmane.linux.drivers.video-input-
infrastructure/6320/focus=6425), VIDIOC_[GS]_JPEGCOMP ioctls are deprecated 
and should be replaced by controls. Nobody has had time to write a spec yet, 
so JPEG support is currently stalled.

Regards,

Laurent Pinchart

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