On Thu, 2010-01-21 at 07:26 -0800, k niemand wrote:
> I connected the cable directly into the analog RF tuner and the lines
> disappeared. When I plugged the cable box output into the RF tuner the
> lines re-appeared (same when I plug it in via svideo). The cable box
> is a Motorola DCH70. Any idea what is going on and how this can be
> fixed?
>
> Thanks a lot for your help,
> Joe
(Please keep posts on the list.)
What can I say? Your digitial cable box is digitizing and then
reconstructing the analog signal. And it is doing something
non-standard or wrong in the reconstructed output:
1. wrong number of vertical sync pulses?
2. wrong number of VBI lines?
3. delaying active video by one line?
All of which a normal analog TV won't show you, because the first few
lines are not shown anyway.
I did a lot of research in fixing up the leacy code from cx25840 that is
in cx18-av-core. I had a broadcast NTSC signal source at the time I
fixed the VBI support. So, I'm sure I've got all the line timings right
for standard NTSC.
You can gripe to Motorola that their box doesn't do the right thing, but
I suspect they will not care.
The quickest and easiest solution is to use a splitter, bypassing the
cable box and not digitizing the signal twice, if the video atrifact
from Motorola bothers you.
I could look into fixing the CROPCAP ioctl() in cx18 if it is broken.
However, the interaction with VBI decoding could be complex and could
take me a lot of time.
Also, patches are welcome. If you've got some fixes for cx18-av-*.c,
cx18-ioctl.c, and cx18-vbi.c that fixes the problem without disrupting
VBI capture, that would speed a fix along. (The publicly available
CX25840/1/2/3 datasheet has most of the information you would need, with
the BT878A datasheet providing some additional information to fill in
the blanks.)
Regards,
Andy
> --- On Wed, 1/20/10, Andy Walls <awalls@radix.net> wrote:
>
> > From: Andy Walls <awalls@radix.net>
> > Subject: Re: [ivtv-users] CX18: Black and white horizontal line with HVR-1600
> > To: "User discussion about IVTV" <ivtv-users@ivtvdriver.org>
> > Cc: jknoedel@yahoo.com
> > Date: Wednesday, January 20, 2010, 8:57 PM
> > On Wed, 2010-01-20 at 14:22 -0800, k
> > niemand wrote:
> > > Hi Andy,
> > > I am residing in the US and I am using the HVR-1600 to
> > watch some broadcasting from my cable box (using s-video). A
> > while back you had mentioned that you were going to work on
> > the VBI issue of this card. I saw that you had completed
> > support for sliced and raw VBI for 625 line system. I
> > recently downloaded a fresh v4l-dvb copy from the mercurial
> > deposit and compiled it. On my system (NTSC, s-video from a
> > cable box), I still see the black and white horizontal line
> > on the top. In one of your earlier email you wrote:
> > > "The wrong values for vblank and vactive may be being
> > used in the
> > > cx18-av-core.c file."
> > >
> > > Any idea what it would take to get this working for
> > NTSC? I am more
> > > than happy to try out some changes.
> >
> > The latest changes for NTSC and other 525 line systems
> > should already
> > have this fixed. Quite a while ago in fact:
> >
> > changeset: 10446:d6f1e45f8167
> > user: Andy Walls <awalls@radix.net>
> > date: Sun Feb 08 20:40:04 2009
> > -0500
> > summary: cx18: Finally get sliced
> > VBI working - for 525 line 60 Hz systems at least
> >
> >
> > The driver should not provide any visible NTSC VBI lines at
> > the top of
> > the screen.
> >
> > If you bypass the cable box, and connect the coaxial cable
> > into the
> > analog RF tuner connector of the HVR-1600 and use the
> > HVR-1600's tuner,
> > do you get the black and white VBI line at the top of the
> > frame? Is it
> > on all channels?
> >
> > Regards,
> > Andy
> >
> > > Thanks a lot,
> > >
> > > Joe
> > >
> > > --- On Tue, 2/24/09, k niemand <jknoedel@yahoo.com>
> > wrote:
> > >
> > > > From: k niemand <jknoedel@yahoo.com>
> > > > Subject: Re: [ivtv-users] CX18: Black and white
> > horizontal line with HVR-1600
> > > > To: ivtv-users@ivtvdriver.org
> > > > Date: Tuesday, February 24, 2009, 9:32 AM
> > > >
> > > > I had downloaded the lates one a couple of weeks
> > ago,
> > > > compiled it and installed it, but the problem is
> > still
> > > > there.
> > > >
> > > > Thanks for all the work,
> > > > Joe
> > > >
> > > > >
> > > > > Well I'd suggest the latest driver from the
> > main
> > > > > repository:
> > > > >
> > > > > http://linuxtv.org/hg/v4l-dvb
> > > > >
> > > > > and see if the problem still persists.
> > If dmesg
> > > > tells you
> > > > > right now
> > > > > that you're using a cx18 driver less than
> > version
> > > > > 1.0.4, things should
> > > > > get better with the latest driver.
> > > > >
> > > > > Instructions are here:
> > > > >
> > > > > http://www.ivtvdriver.org/index.php/Cx18
> > > > >
> > > > > but last I heard, Ubuntu does some
> > distribution
> > > > specific
> > > > > things that may
> > > > > make compiling the latest v4l-dvb repo
> > harder than it
> > > > has
> > > > > to be. Sorry,
> > > > > I won't be able to help with that if that's
> > the
> > > > > case.
> > > > >
> > > > >
> > > > > > Any idea of when you have time to look
> > at this
> > > > issue?
> > > > > It sounds like
> > > > > > you are very busy.
> > > > >
> > > > > I'm travelling off and on the the next two
> > weeks, so
> > > > > I'm not sure when I
> > > > > will be looking at it.
> > > > >
> > > > > Regards,
> > > > > Andy
> > > > >
> > > > > > Anything I can try?
> > > > > >
> > > > > > Thanks,
> > > > > > Joe
> > > > > >
> > > > > >
> > > > > >
> > > > > > --- On Thu, 2/12/09, Andy Walls
> > > > > <awalls@radix.net>
> > > > wrote:
> > > > > >
> > > > > > > From: Andy Walls <awalls@radix.net>
> > > > > > > Subject: Re: [ivtv-users] CX18:
> > Black and
> > > > white
> > > > > horizontal line with HVR-1600
> > > > > > > To: jknoedel@yahoo.com,
> > > > "User discussion
> > > > > about IVTV" <ivtv-users@ivtvdriver.org>
> > > > > > > Date: Thursday, February 12, 2009,
> > 10:45 PM
> > > > > > > On Thu, 2009-02-12 at 17:11 -0800,
> > k
> > > > niemand
> > > > > wrote:
> > > > > > > > I have a HVR-1600 card and
> > installed
> > > > the
> > > > > latest
> > > > > > > driver. I use the
> > > > > > > > latest Ubuntu distribution.
> > Composite
> > > > input
> > > > > works fine
> > > > > > > apart from an
> > > > > > > > annoying black and white
> > horizontal
> > > > line at
> > > > > the top of
> > > > > > > the picture. I
> > > > > > > > tried the --set-crop option
> > using
> > > > v4l2-ctl
> > > > > (v4l2-ctl
> > > > > > > > --set-crop=top=1), but the
> > responds I
> > > > get is
> > > > > > > "VIDIOC_G_CROP: failed:
> > > > > > > > Invalid argument".
> > > > > > >
> > > > > > > The driver doesn't really support
> > the crop
> > > > > ioctl. It
> > > > > > > provides a stub
> > > > > > > that goes through some trivial
> > motions, but
> > > > then
> > > > > always
> > > > > > > returns -EINVAL.
> > > > > > >
> > > > > > >
> > > > > > > > Does anyone have any ideas of
> > how to
> > > > get rid
> > > > > of this
> > > > > > > line?
> > > > > > >
> > > > > > > Well, I have to fix the driver to
> > get rid of
> > > > it.
> > > > > > >
> > > > > > > That line is part of the Vertical
> > Blanking
> > > > > Interval; the
> > > > > > > white areas are
> > > > > > > data that's being sent (like CC
> > over NTSC
> > > > or
> > > > > VPS or
> > > > > > > Teletext for other
> > > > > > > video standards). The wrong
> > values for
> > > > vblank
> > > > > and vactive
> > > > > > > may be being
> > > > > > > used in the cx18-av-core.c file.
> > > > > > >
> > > > > > > Are you using PAL, SECAM, or
> > NTSC? Is
> > > > this a new
> > > > > problem,
> > > > > > > or one that
> > > > > > > you have always had? What is
> > the
> > > > composite video
> > > > > source: a
> > > > > > > VCR, a cable
> > > > > > > convertor, or something else?
> > > > > > >
> > > > > > > Regards,
> > > > > > > Andy
> > > > > > >
> > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Joe
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > _______________________________________________
> > > > > > ivtv-users mailing list
> > > > > > ivtv-users@ivtvdriver.org
> > > > > > http://ivtvdriver.org/mailman/listinfo/ivtv-users
> > > > > >
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > ivtv-users mailing list
> > > > ivtv-users@ivtvdriver.org
> > > > http://ivtvdriver.org/mailman/listinfo/ivtv-users
> > > >
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > ivtv-users mailing list
> > > ivtv-users@ivtvdriver.org
> > > http://ivtvdriver.org/mailman/listinfo/ivtv-users
> > >
> >
> >
>
>
>
>
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