I have a working 10.04 Mythbuntu system, using a PVR-150 tuner card. The PVR-150 is configured with two inputs: a coax from my analog cable feed, and an S-Video input from a 'static' video source. No IR blasters or remote channel changing is involved.
All has been working well, except that the audio levels between the two video inputs are quite different. Recordings made from the S-video input have very low audio, and we have to crank the TV volume to the max in order to hear anything. Thanks to helpful posts on this forum and elsewhere, I figured out how to use the External Channel Change command (as defined in mythbackend's Input Connections) to override the default volume settings. I created a couple of scripts to invoke v4l2-ctl and send new volume settings to the PVR-150, one script for each input. (for good measure, I also tweaked the video saturation and brightness settings to get more consistent picture quality).
My problem is that the internal channel change function no longer works. The tuner input on the PVR-150 is now stuck on channel 2. If I run LiveTV and try to change the channel, the OPG indicates that a new channel is being selected, but the video doesn't change.
My guess is that the presence of the External Channel Change Command is disabling MythTV's internal channel changer. If so, can I embed something inside my external command script that will invoke the system's channel changer??
Or perhaps it's a timing conflict: my script might be sending control settings to the tuner card at the same time that the internal channel changer is trying to send the channel-change command.
Here is one of the scripts I'm using to fiddle the audio/video parameters. I've never written a script before so I'm sure there is room for improvement. The logging I put in indicates that it is working as intended.
Code:#!/bin/bash # /usr/local/bin set_svid_ctrls.sh # script to set control parameters for S-Vid input on PVR-150 DEVICE="-d /dev/video-PVR150" exec >>/var/log/mythtv/set_tuner.log 2>&1 echo "called for S-vid input" echo Settings before: v4l2-ctl $DEVICE -l | head -8 | tail -5 #control settings B=150 #picture brightness (0-255) S=40 #saturation (0-127) V=65000 #volume (0-65535) v4l2-ctl $DEVICE --set-ctrl brightness=$B,saturation=$S,volume=$V >/dev/null #kick the audio input for good measure (tinny audio problem) v4l2-ctl $DEVICE --set-audio-input=1 >/dev/null echo ;echo Settings after: v4l2-ctl $DEVICE -l | head -8 | tail -5 echo ====================