[sane-devel] Invalid argument (status 4) when calling sane_start

[m. allan noah]

On 12/16/07, Peter Gebauer <petgeb at users.sourceforge.net> wrote:
> Hi!
>
> > The v4l backend supports only a few modes so you have to select the correct ones to get a image.
>
> So it's the v4l settings that are wrong or the SANE settings?
>
> There's a couple of things I'd fix with the v4l backend
>
> 1) Default (startup) mode must be valid and supported so a user can
> sane_start() with the default settings. It makes no sense to put the device
> in "broken mode" at startup.
>
> 2) Unsupported modes should not be listed. Why whould you even list
> options/modes that aren't supported by the backend? Nobody wants a
> SANE_STATUS_INVAL so nobody will set an unsupported mode anyway. Any modes
> not supported should be removed from the options.
>
> If your sane_control_option didn't give an error then that mode should be
> considered valid and usable setting. This will remove the unwanted surprise
> when calling sane_start() and it will remove the guess work trying to figure
> out what option is breaking the sane_start() call.
>
> I'll look at the v4l backend, but fixing it to work properly would be a
> major detour from my project. The idea of allowing SANE to use v4l devices
> is great, it feels generic and... cool. :)

yes, it does sound nice, but sane devels are generally volunteers, who
only have time to scratch their particular itch. the v4l backend is
clearly labled as ALPHA in its man page. Since the rest of us dont
seem to use it, maybe it was waiting on you to finish it :)

allan

>
> /Peter
>
>
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