Part 2: Connections and Configuration
In part one of this series, I covered the hardware and basic operating system installation for a home theater PC running Mythbuntu. In other words, part one covered the easy stuff. Running the audio cables between the PC and the TV is actually a more complicated affair than I had imagined, yielding three major issues that had to be overcome before ending up with an acceptable configuration.
The blue lights are very subtle, but neat in the dark
1. Audio
I should clarify that connecting the cables isn’t the problem, it is the technical limitations and configuration issues accompanying their connection that poses challenges. My audio connection is straight stereo-out to stereo-in via a 10 foot 3.5mm interconnect. Upon plugging it in and turning on the TV however, no audio was present. The reason behind the problem ended up being with how ALSA was loading modules, and was easily fixed with a configuration change. If you copy my setup and are using a Creative Audigy 2 sound card with an Ubuntu variant, try the following:
- Run ‘alsamixer’ on the command line and verify your Master and PCM channels are turned up.
- Verify you have your cable plugged in to the correct slot on your sound card.
- My fix: another sound device (my motherboard’s onboard sound) was stealing ALSA’s focus. Adding the following to /etc/modprobe.d/blacklist and rebooting fixed my problem:
blacklist snd_intel8x0
2. Video – Analog Connection via DSUB15
The Viera has an analog mini-DSUB 15 port for hooking up a PC directly to the TV. I had never had an issue with signal quality before on smaller monitors, so I didn’t forsee any problems with hooking a ten foot VGA cable from the computer to the TV. There are a multitude of issues with this setup, however.
First, read the specifications for the Viera carefully (in the manual, I couldn’t find the information anywhere else), and Panasonic states the TV is capable of producing a maximum resolution of 1280×1024@60hz. This is a slight problem, because in order to display content at 1080p, 1080 lines of vertical resolution are needed. Furthermore, with a 10′ run of analog signal 1024×768 is clean, but pushing 1280×1024 causes a significant amount of signal and color bleeding.
The pits of this is that if you stick with an analog connection, you are really stuck with these problems. You can clean up the signal by running a shorter cable from the HTPC and the TV, but that limits the placement of the machine. The resolution limitation is the real kicker, as spending all of that money on a HDTV capable of producing 1080p becomes a complete waste if you can only fully display 720p content. I refused to believe that the TV couldn’t produce its native resolution of 1920×1080 from a computer source, so the next fix comes from addressing that issue.
3. Video – Digital Connection via DVI -> HDMI (and More Audio Solutions)
The TV is capable of producing 1080p from a source connected through component or HDMI cables, displaying at 1920×1080. My solution to the problems found in section two of this post was to then find a way to get my HTPC’s video output to an HDMI cable. HDMI is really only DVI with added support for sound, so another $15 purchase of a DVI -> HDMI cable and a week of waiting was all I needed to make the connection. The benefit was immediate – being digital, there is no signal bleeding or interference. The drawbacks presented themselves just as quickly, however. I found that my analog audio connection had cut out, I could no longer produce sound on the TV. Additionally, the HTPC was displaying at 1920×1080, but the TV was only displaying a portion of it, with my mouse going off-screen to access common menus.
The video display was the most immediately annoying part. Reading many online forums suggested that it was a problem with overscanning, and there were even guides on how to access the service menus of the Viera to grant a 1:1 pixel match (effectively disabling overscanning). I haven’t found this documented anywhere else, so I want to say it clearly: ADJUSTING YOUR VIERA’S OVERSCAN SETTINGS IS UNNECESSARY (is it still bad design to use marquee and blink tags? I’m tempted to use them here). The easy and smart fix is documented in the service manual (not the user manual), and is as easy as the following:
- Plug in your DVI -> HDMI cable, ensure your source HTPC is on and change the TV’s video input so the HTPC’s screen is visible.
- On your remote, press “Menu,” then go to “Picture”
- Scroll down to the second screen, and go to “Advanced Picture”
- Go to the last option, “HD size,” and change it from “1″ to “2″
That fixed it for me. Restarting Xorg and a change of the resolution to 1920×1280@55hz had me running in full high-def glory. But without sound.
The sound issue was a nuisance. HDMI normally carries a digital audio signal with the digital video feed, so the Viera is nice enough to automatically ignore all analog audio input sources when your display comes from an HDMI source. Unfortunately, getting audio spit out over DVI was more difficult than I cared to pursue (with a lot of forums claiming the task impossible), and buying a DVI + analog audio -> HDMI converter is in excess of 200 euros. Again, the simpler and smarter solution is again in the Viera service manual (not the user manual), and can again be done by following these steps:
- Plug in your HTPC and get it set up again so the screen is visible.
- On your remote, press “Menu,” then go to “Audio”
- Select “Advanced audio”
- Go to “HDMI 1 in” (or to whichever port your HTPC is plugged in to)
- Scroll over until the port your audio source is in is selected (I selected “PC”)
You should now have overridden the default of using the digital signal from your HDMI cable to now use the analog input.
For me, these three steps resolved the major issues (and relieved the major headaches) I encountered while setting up my HTPC. I sincerely hope that these steps will help people avoid making the mistakes I did, and save them the many days spent polling forums looking for answers to these issues. In part three of this series of posts, I will address setting up the system to make retrieving media especially easy, and some other configuration tweaks that make my system an easy-to-use content retrieving monster. Subscribing to my RSS feed will ensure you don’t miss it.
I’m off to watch The Dark Knight in 1080p – until next time!
1080p plasma TV at the beginning of January, and the resulting fun I’ve been having with it is largely responsible for my lack of recent blog updates. I, being the cheap geek I am, have no desire to either pay for an HD package from my cable company, nor do I want to go out and buy an HD source and then buy or rent movies. The solution I came up with to view my existing media and new HD content thus revolves around a relatively cheap solution – a home theatre PC (HTPC). There were significant challenges in getting everything set up how I wanted it, and to prevent others from having to repeat my failures, I’m going to post a multi-part guide to repeating my final configuration – which looks a little like this. Part 1 after the jump!
