[ivtv-users] cx18

[Al McIntosh]

On Sat, Nov 22, 2008 at 10:00 AM, Andy Walls <awalls at radix.net> wrote:

> On Fri, 2008-11-21 at 15:28 +0200, Dmitry Podyachev wrote:
> > is any tools for it ? or is it possible to use some API from v4l for it
> > (I do not see any way - may be via some gpio ?)?
> > > 1. The strategy may be to check the AGC level after the AGC settles
> > > after tuning to a channel or switching to a baseband input.  If the
> > > level is up near the top of the AGC's range, maybe +9 dB out of the +12
> > > dB max (0x36 or 0x37 in register 0x488) then turn on the +12 dB
> > > amplifier for the input to get more dynamic range out of the final
> stage
> > > of the amplifier.
> > >
> >
> > > 2. Maybe you could also, after changing the channel and letting the AGC
> > > settle, record the AGC value for that channel or input and then put the
> > > AGC in a manual mode
> >
> > yes, but how? how write something manual to AGC register ? write c-code
> > or other way exist ?
> >
>
>
> Look at the definitions on page 5-92 and 5-93 of
>
> http://dl.ivtvdriver.org/datasheets/video/cx25840.pdf
>
> And the experiment using v4l2-dbg as root:
>
> # v4l2-dbg -d /dev/video0 -R type=host,min=0x2c40488,max=0x2c4048f
> ioctl: VIDIOC_DBG_G_REGISTER
>
>                00       04       08       0C       10       14       18
>   1C
> 02c40480:                   f825ea1c 001020dc
>
>
> Note when using the HVR-1600's built in NTSC tuner, tuned to an over the
> air broadcast signal, VGA gain on my card is at 0x1c right now which
> corresponds to 0.875 or -1.16 dB: close to the middle of it's range. The
> Digital AGC, which comes after the VGA, has adjusted it's fine gain to
> 0x5ea.
>
>
> What gain is your card's VGA set at when video comes from the source
> with which you have problems?
>
>

Andy, I am trying to record from SVIDEO 1, something I did not think to
mention.

$ v4l2-ctl --get-input
Video input : 1 (S-Video 1)
$ v4l2-ctl --get-tuner
Tuner:
        Capabilities         : 62.5 kHz multi-standard stereo lang1 lang2
        Frequency range      : 44.0 MHz - 958.0 MHz
        Signal strength      : 99%
        Current audio mode   : lang1
        Available subchannels: mono


Here is the output:


$ sudo v4l2-dbg -d /dev/video0 -R type=host,min=0x2c40488,max=0x2c4048f

ioctl: VIDIOC_DBG_G_REGISTER

                00       04       08       0C       10       14
18       1C
02c40480:                   f825451d 001020dc





I am quite suprised how great the system requirements are for this card.
When I first tried to boot the computer it wouldn't boot, I had to raise
vmalloc to 192M it's currently consuming about 120M+/-.

The card worked well in my dual core amd64 but I will need an IR Blaster in
order to migrate everything to that machine.


Thanks for all of the energy you're putting into this... I really do
appreciate this.
Al
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