[mythtv-users] WinTV-Go no longer giving TV Line-out sound

Bruce Markey bjm at lvcm.com
Tue Dec 26 21:59:57 UTC 2006


terevos wrote:
...
> The WinTV-Go card is no longer giving TV Line-out sound. I plugged a
> set of headphones into the card while it was tuned to a TV channel and
> no sound came out.

That's the right test. Good job. So, either the audio chip
on the card died or the registers are set to not output audio.

> Background:
> I had setup Fedora Core 4 with MythTV and the WinTV-Go card. It was
> working for well over a year, and then I just got a Hauppauge PVR-150
> for Christmas. So I installed it (and had various issues to deal with)
> and eventually got it working. But now I have the problem with the old
> WinTV-Go card.

Is it possible that you upgraded the kernel and drivers for
the first time in a long time when installing the ivtv card?

Something changed a while back where linux or bttv sets a mute
bit that needs to be flipped before it will output audio.

If you haven't already, install "xawtv" which is the player from
the guys that wrote bttv. The package includes other useful tools
like "v4lctl" to view and set driver parameters.

: bjm at nordtv ; v4lctl list
attribute  | type   | current | default | comment
-----------+--------+---------+---------+-------------------------------------
norm       | choice | NTSC    | PAL     | PAL NTSC SECAM PAL-Nc PAL-M PAL-N NTSC-JP PAL-60
input      | choice | S-Video | Televis | Television Composite1 S-Video Composite3
audio mode | choice | lang1   | mono    | mono stereo lang1 lang2
bright     | int    |   40700 |   32768 | range is 0 => 65535
contrast   | int    |   27300 |   32768 | range is 0 => 65535
color      | int    |   32768 |   32768 | range is 0 => 65535
hue        | int    |   32768 |   32768 | range is 0 => 65535
volume     | int    |       1 |   65535 | range is 0 => 65535
Balance    | int    |   32768 |   32768 | range is 0 => 65535
Bass       | int    |   32768 |   32768 | range is 0 => 65535
Treble     | int    |   32768 |   32768 | range is 0 => 65535
mute       | bool   | on      | off     |
chroma agc | bool   | on      | off     |
combfilter | bool   | on      | off     |
automute   | bool   | on      | off     |
luma decim | bool   | on      | off     |
agc crush  | bool   | on      | off     |
vcr hack   | bool   | off     | off     |
whitecrush | int    |     253 |     207 | range is 0 => 255
whitecrush | int    |     127 |     127 | range is 0 => 255
uv ratio   | int    |      52 |      50 | range is 0 => 100
full luma  | bool   | on      | off     |
coring     | int    |       1 |       0 | range is 0 => 3

I use a wrapper script to make sure a bunch of parameter are
set correctly each time I start any backend:

#!/bin/sh
#
# mb: wrapper script for mythbackend
#
v4lctl -c /dev/video0 setattr 'chroma agc' on > /dev/null 2>&1
v4lctl -c /dev/video0 setattr 'combfilter' 2  > /dev/null 2>&1

v4lctl -c /dev/video0 setattr 'mute' off > /dev/null 2>&1

v4lctl -c /dev/video0 setattr 'uv ratio' 52 > /dev/null 2>&1
v4lctl -c /dev/video0 setattr 'whitecrush upper' 253  > /dev/null 2>&1
v4lctl -c /dev/video0 setattr 'luma decimation filter' on > /dev/null 2>&1

if [ -x /usr/local/bin/v4l2-ctl ]; then
    v4l2-ctl -c temporal_filter=4 -d /dev/video1 > /dev/null 2>&1
    v4l2-ctl -c loudness=1 -d /dev/video1 > /dev/null 2>&1
fi

mythbackend "$@" -d -l /var/log/myth/mb.log -p /tmp/mb.pid


The important one here is "v4lctl setattr 'mute' off". About
a year or two ago, new kernel builds would mute the card until
this command was run. Try it and see if you get audio from
headphones plugged into the WinTV-Go card. Else, you may
have shocked your card while moving things around :-(.

--  bjm


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