Monday, 15 September 2008, 16:20:22 EDT
Speaking of problems with my MythTV machine, I recently lost sound on the machine. I built my HTPC (Home Theatre Personal Computer) to be a High-Definition machine. As such, I intended to have one cable connecting the HTPC to my television — an HDMI cable. I specifically bought a nVidia GeForce 8500GT because it uses passive cooling (no fan noise) and has an SPDIF audio input so that it can pass audio out over an HDMI cable. After putting the machine together, and getting it all setup, I discovered that the nVidia drivers for Linux did not support passing audio over the HDMI cable. So I sighed, maybe said a few choice words in nVidia's direction, and connected an eighth inch DIN to RCA cable between the HTPC and my television. All was dandy!
Fast forward to last Thursday, when I decided to work on my HTPC. The first thing I did was update the operating system and software. That meant I got new video card drivers; version 173 instead of the old version 169. Suddenly I had no sound! Actually, I had much weirder problem. I could play sound at the console, before starting the X session, but got only silence after X had started. It took me a while to discover this, but once I did, it was clear that the video card driver was doing something very strange. After a bit of searching, I came across a single forum post that gave me the answer. In the 173 version of the driver, nVidia had silently enabled audio over HDMI (oh the irony!).
I spent hours trying to get sound to play via the HDMI cable. But for some reason my machine just will not do it (I'm beginning to think the patch cable from the sound card to the video card is bad). So I switched over to a regular VGA connection. I quickly got tired of that. The picture was blurry and I had to restart X multiple times whenever I turned on the television, because the display wasn't syncing properly.
In an effort to get this resolved, I wrote a lengthy post ... (view rest)
Sunday, 14 September 2008, 17:23:47 EDT
Several months ago I built a MythTV computer. Since I built it during spring semester I didn't really have the time to fully configure the machine. So it's been in a usable but needs work state ever since. One of the biggest problems was getting the machine to boot into the MythTV frontend application without requiring a login every time. The GNOME Display Manager would allow me to specify an automatic login, but that only works for the first login. So if I had to quit the MythTV frontend for some reason, GDM would automatically come back up, but then ask for a username and password. SLiM recently (as in 9/7/2008) added support for an automatic login, but it also only works for the first login. This seems to be the way of things for this type of application. They will automatically login a user the first time, but not subsequent times, and there is no way to make the programs quit after one execution.
This situation was unacceptable to me. I needed a login manager that would do three simple things:
Automatically login a chosen user.
Grant the user privileges as defined by PAM.
Quit execution when the X session was quit.
Since I could not find such a simple program, I wrote my own. In my code section you can find the source code to a program "mythlogin".
Why not just execute xinit directly from inittab? As of Linux kernel 2.6.24 it is necessary to establish privileges through PAM in ord ... (view rest)