Cropping with Hauppauge HVR-1900

Cropping with Hauppauge HVR-1900

[jmdk]

Hello,

I have a Hauppauge HVR-1900 which works fine with the pvrusb2 driver.
However because most TV channels now air with 16:9 content inside 4:3
images, I would like to crop out the top and bottom black bars before
encoding via the hardware MPEG2 encoder. I tried using the ctl_crop_top
and ctl_crop_height in  /sysfs as well as the --set-crop option of
v4l2-ctrl but only received error messages indicating a value out of range.

The card has a cx25843 which should support cropping. Does anyone know
how to get this feature to work ?

Thanks in advance for the help,

Joseph

Re: Cropping with Hauppauge HVR-1900

[Mike Isely]

On Fri, 26 Jun 2009, jmdk wrote:

> Hello,
> 
> I have a Hauppauge HVR-1900 which works fine with the pvrusb2 driver.
> However because most TV channels now air with 16:9 content inside 4:3
> images, I would like to crop out the top and bottom black bars before
> encoding via the hardware MPEG2 encoder. I tried using the ctl_crop_top
> and ctl_crop_height in  /sysfs as well as the --set-crop option of
> v4l2-ctrl but only received error messages indicating a value out of range.
> 
> The card has a cx25843 which should support cropping. Does anyone know
> how to get this feature to work ?
> 
> Thanks in advance for the help,

Unfortunately the cx25840 driver does not implement any cropping 
capability and the recent change to the v4l-subdevice architecture 
currently lacks the API entrypoints to make such a thing possible :-(

A pvrusb2 user a while back (it's in the pvrusb2 list archives) came up 
with some patches to the cx25840 driver that implement cropping.  He 
also generated corresponding patches for the pvrusb2 driver.  I merged 
his pvrusb2 patches (which is why you see that support in the driver) 
but not the cx25840 patches since I'm not an expert on that chip and I 
don't have the ability to verify that the patches preserve correct 
behavior for all the other devices that use the same chip.  I did pass 
the cx25840 patches to Hans Verkuil and he tried them out at the time 
and basically pronounced them "ok" but I think even he wasn't sure if it 
was doing everything right.

That was a while ago and the cx25840 driver has undergone enough other 
changes to make merging those patches a lot more difficult - plus the 
v4l-subdevice stuff needs additional changes to support the extra 
cropping API.

  -Mike


-- 

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

Re: Cropping with Hauppauge HVR-1900

[Hans Verkuil]

On Friday 26 June 2009 18:33:11 Mike Isely wrote:
> On Fri, 26 Jun 2009, jmdk wrote:
> 
> > Hello,
> > 
> > I have a Hauppauge HVR-1900 which works fine with the pvrusb2 driver.
> > However because most TV channels now air with 16:9 content inside 4:3
> > images, I would like to crop out the top and bottom black bars before
> > encoding via the hardware MPEG2 encoder. I tried using the ctl_crop_top
> > and ctl_crop_height in  /sysfs as well as the --set-crop option of
> > v4l2-ctrl but only received error messages indicating a value out of range.
> > 
> > The card has a cx25843 which should support cropping. Does anyone know
> > how to get this feature to work ?
> > 
> > Thanks in advance for the help,
> 
> Unfortunately the cx25840 driver does not implement any cropping 
> capability and the recent change to the v4l-subdevice architecture 
> currently lacks the API entrypoints to make such a thing possible :-(
> 
> A pvrusb2 user a while back (it's in the pvrusb2 list archives) came up 
> with some patches to the cx25840 driver that implement cropping.  He 
> also generated corresponding patches for the pvrusb2 driver.  I merged 
> his pvrusb2 patches (which is why you see that support in the driver) 
> but not the cx25840 patches since I'm not an expert on that chip and I 
> don't have the ability to verify that the patches preserve correct 
> behavior for all the other devices that use the same chip.  I did pass 
> the cx25840 patches to Hans Verkuil and he tried them out at the time 
> and basically pronounced them "ok" but I think even he wasn't sure if it 
> was doing everything right.
> 
> That was a while ago and the cx25840 driver has undergone enough other 
> changes to make merging those patches a lot more difficult - plus the 
> v4l-subdevice stuff needs additional changes to support the extra 
> cropping API.

Just a quick heads-up: the cropping API will be added to the v4l2_subdev API
soon. A pull request from Guennadi that does this is already posted to the
list.

Regards,

	Hans

-- 
Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom

Re: Cropping with Hauppauge HVR-1900

[Andy Walls]

On Fri, 2009-06-26 at 11:33 -0500, Mike Isely wrote:
> On Fri, 26 Jun 2009, jmdk wrote:
> 
> > Hello,
> > 
> > I have a Hauppauge HVR-1900 which works fine with the pvrusb2 driver.
> > However because most TV channels now air with 16:9 content inside 4:3
> > images, I would like to crop out the top and bottom black bars before
> > encoding via the hardware MPEG2 encoder. I tried using the ctl_crop_top
> > and ctl_crop_height in  /sysfs as well as the --set-crop option of
> > v4l2-ctrl but only received error messages indicating a value out of range.
> > 
> > The card has a cx25843 which should support cropping. Does anyone know
> > how to get this feature to work ?
> > 
> > Thanks in advance for the help,
> 
> Unfortunately the cx25840 driver does not implement any cropping 
> capability and the recent change to the v4l-subdevice architecture 
> currently lacks the API entrypoints to make such a thing possible :-(
> 
> A pvrusb2 user a while back (it's in the pvrusb2 list archives) came up 
> with some patches to the cx25840 driver that implement cropping.  He 
> also generated corresponding patches for the pvrusb2 driver.  I merged 
> his pvrusb2 patches (which is why you see that support in the driver) 
> but not the cx25840 patches since I'm not an expert on that chip and I 
> don't have the ability to verify that the patches preserve correct 
> behavior for all the other devices that use the same chip.  I did pass 
> the cx25840 patches to Hans Verkuil and he tried them out at the time 
> and basically pronounced them "ok" but I think even he wasn't sure if it 
> was doing everything right.
> 
> That was a while ago and the cx25840 driver has undergone enough other 
> changes to make merging those patches a lot more difficult - plus the 
> v4l-subdevice stuff needs additional changes to support the extra 
> cropping API.

Not only that, doing cropping with the CX2584x chips and friends appears
to break VBI extraction in interaction with the CX2341x encoding engine.

A good bit of experimentation would need to be done to keep VBI working
with cropping.

Regards,
Andy

>   -Mike