[pvrusb2] [patch] capture window centering via VIDIOC_S_CROP

[Mike Isely]

On Fri, 9 May 2008, vdb128 at picaros.org wrote:

> The pvrusb2 patches here below implement capture window centering 
> by adding the controls crop_left and crop_top.  They call the v4l2 
> ioctl VIDIOC_CROPCAP and VIDIOC_S_CROP to get the capture 
> rectangle default and to set the margins.  
> 
> The cx25840 kernel module patches implement these controls by 
> shifting the analog capture window.  The two sets are independent.  
> 
> Horizontal center adjustment is useful when capturing from cable 
> tv or a settop box.  The default is fine for vhs playback but cuts 
> off the right border of a broadcast 720 dot image.  E.g.
> 
>   echo +4 >ctl_crop_left/cur_val  #shifts the window to the right.
> 
> Vertical center adjustment is needed for newer encoder firmwares.  
> These capture too late and add 2 black lines at the bottom.  E.g.
> 
>   echo -2 >ctl_crop_top/cur_val  #shifts the window up.
> 
> The approach should work for any system but is as yet untested for 
> broadcast M ntsc.  

   [...]

I briefly scanned through the pvrusb2 part of the code and it appears 
that you have really nailed down how the controls work in the driver.  
Great job.  I will play around with this a bit (in NTSC-M BTW) and if 
there aren't any issues I'll merge it in.

The cx25840 driver part is a different issue.  I don't maintain that 
driver.  However I will see about getting those changes reviewed and 
pushed up into the V4L-DVB repository.

Thanks.

  -Mike

-- 

Mike Isely
isely @ pobox (dot) com
PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8