[mythtv-users] analog video camera and Mythtv?

[Nick]

On 25/01/06, Roger Hanson <roger at rogerhanson.com> wrote:
>  Michael T. Dean wrote:
>  On 01/25/2006 11:06 AM, David Watkins wrote:
>
>
>  I suggest looking to see what other /dev/video devices exist on your
> system, and trying them in place of /dev/video0. I think one of the
> setup pages of mythtvsetup shows you which input is on which device.
> I'm afraid I don't know enough of the theory to suggest a more
> scientific approach.
>
>
>  video0 is the MPEG-2 video from whichever input the card is set to use.
> You don't change inputs by changing video devices, you change with
> "ivtvctl -p" so see "ivtvctl --help"
>
> Mike
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>
>
>
>  Thanks - made progress, but the recording was in black and white, not color
> like the original.....weird.
>
>  I did a ivtvctl -p=4
>  I used dd if=/dev/video0 of=/myth/tv/myfile.mpg bs=64k
>  I got black/white output (was recorded in color)
>
>  ivtvctl -p=6
>  I used dd if=/dev/video0 of=/myth/tv/myfile.mpg bs=64k
>  I got black/white output (was recorded in color)
>
>  Did I do something wrong?

Which input did you setup for Myth to use? This is the one you should
be trying from the command line. Running 'ivtvctl -a' will give a list
of all the inputs/outputs the ivtv driver can access on your card. You
need to match the text from mythtvsetup (i.e. S-Video 0) to the input
id per ivtvctl. You then need to change to this using 'ivtvctl -p x'
where x is the id of the input.

>  mythtv at pvr:~$ dd if=/dev/video4 of=/myth/tv/myfile.mpg bs=64k
>  dd: opening `/dev/video4': No such device
>  mythtv at pvr:~$ dd if=/dev/video6 of=/myth/tv/myfile.mpg bs=64k
>  dd: opening `/dev/video6': No such device
>  mythtv at pvr:~$ su
>  Password:
>  root at pvr:/home/mythtv# dd if=/dev/video6 of=/myth/tv/myfile.mpg bs=64k
>  dd: opening `/dev/video6': No such device
>  root at pvr:/home/mythtv# dd if=/dev/video4 of=/myth/tv/myfile.mpg bs=64k
>  dd: opening `/dev/video4': No such device
>  root at pvr:/home/mythtv# dd if=/dev/video2 of=/myth/tv/myfile.mpg bs=64k
>  dd: opening `/dev/video2': No such device
>  root at pvr:/home/mythtv#

As Mike stated earlier, you _always_ use /dev/video0 (if you have a
single card) when trying to capture MPEG-2 video from the PVR-350
(hence the barrage of error messages).

You first need to select one of the available inputs (i.e. tuner,
Composite, S-Video) using 'ivtvctl -p x' which, when selected, are
"patched" to video0. When using MythTV, all of this input switching is
transparent to the user, but on the command line it is needed.

For example, to switch to the input "Composite 2" (id 2) you would use

# ivtvctl -p 2

To then capture from this input, you would use

dd if=/dev/video0 of=/myth/tv/myfile.mpg bs=64k

Check which input you specified in mythtvsetup and then try to capture
video from /dev/video0 after having switched to this input. You
_should_ get the same results as you saw in MythTV.

Black and white video when you were expecting colour is almost always
(on the PVR cards) due to either selecting the wrong type of input
(S-Video instead of Composite) or using a cable that does not support
S-Video. Finally, ensure that the ivtv driver is autodetecting you
tuner type and correctly setting the video format (you can manually
set this using ivtvctl too).

Nick