[pvrusb2] Some MPEG-controls questions

[Carsten Meier]

Am Thu, 26 Feb 2009 13:02:04 +0100
schrieb Hans Verkuil <hverkuil at xs4all.nl>:

> On Thursday 26 February 2009 10:51:24 Carsten Meier wrote:
> > Hi again,
> >
> > now I'm allowing users to change all controls on a channel-switch,
> > including MPEG ones. (To make the filter-controls accessible) Is it
> > save to change e.g. V4L2_CID_MPEG_VIDEO_BITRATE_PEAK during
> > streaming? If I change it during streaming video to vlc through the
> > sysfs-interface, vlc crashes. But I don't know if this is due to a
> > corrupted stream or just a bug in vlc. Is it save to change even
> > the stream type? Or should I better stop and restart streaming on a
> > channel-switch due to possible stream-parameter changes?
> 
> Looking at the code pvrusb2 is supposed to remember the change but
> only apply it the next time a capture is started. A lot of these
> properties cannot be modified on the fly. I'm not entirely sure
> whether pvrusb2 takes the correct approach by remembering the change
> for the next time. ivtv for example just returns -EBUSY.
> 

At least the filter controls can be changed on the fly during streaming
(tested via v4l2). I think I'll simply stop and restart streaming
to prevent any errors.

> How pvrusb2 handles these requests when they come from the sysfs
> interface, that's something Mike can answer.
> 

I'm not gonna use the sysfs-interface in my app, this was just to test
it.

Thanks,
Carsten