Dan Connolly's tinkering lab notebook

Ditch cable TV? Yes. Build an HD DVR out of old PC parts? Maybe not.

This item was supposed to be entitled Ditching cable for netflix/wii, broadcast HDTV, and a DIY PVR. After watching the digital media marketplace and technology for years, I convinced my family it was time to go for it this summer. We're close, but due to one critical breakdown in my research, we're not quite there.

1. Cancel TV part of double play TV+Internet subscription, reducing it by ~$60/month. We never did go for their triple play with phone service; I signed up for VoIP with ViaTalk when we moved houses a couple years ago, and we've been pretty happy with it. While only the cable company can do on-screen caller-id, I'd rather have stuff like email and SMS notification for messages, for less money. Try it, and tell 'em Dan sent you (referral code 47340A17). Check. 2. Set up TV for broadcast HD TV. The salesperson at Best Buy recommended a$60 active antenna, but we went for the $30 RCA ANT1400 Multi-Directional Digital Flat Passive Home Theater Antenna (White) and it works just fine, even in the basement. Check. 3. Subscribe to Netflix. I wondered about the quality of streaming movies, and the first one we tried was pretty bad. We were planning to buy a Roku box, but first we tried it on my laptop, a MacBook Air, hooked up to the TV. Big mistake. Turns out these things have a well-known cooling problem, and "The problem is aggravated by system-intensive tasks such as video playback". Then we remembered Netflix started supporting streaming to Wii consoles, and we have one of those. It seemed too good to be true, but it's not. It's just like watching a DVD, as far as I can tell. We may or may not ever get a Roku. Check. 4. Cobble together a PVR out of old PC parts. My wife misses some cable-network-only shows, but for the price of a new HD capture card (around$80) it looks like we should be able to timeshift broadcast favorites such as Survivor and Big Bang Theory.
That was the theory, anyway.
I thought the hard part was video capture, encoding, and recording. Sucking in HD video through a USB gizmo seemed too good to be true; plus, the norm with USB gizmos is that half the smarts is in a proprietary, Windows-only driver.

But most of the HD capture cards plug into a PCI express slot, and I think my machines are too old to have one of those. Hauppage linux support and the linuxtv wiki agreed that the Hauppauge WinTV-HVR-950Q was supported, and the Micro Center web site showed there were 2 in stock just down the road.

After just a bit of puzzling over the docs for Testing your DVB device, I figured out that I needed to tell the scanning tool to use the north america list of frequencies in order to build a channels.conf file.  After that, I just followed my nose through getting it to work with mplayer, freevo, and eventually, mythtv.

All this was on my desktop machine. Now it was time to use this knowledge to get it running on an old klunker PC that I could put next to the TV downstairs. I shuffled some parts around between two old machines, plugged in the resulting frankenputer, and flipped the switch. Nothing. Maybe a short somewhere... disconnect the power supply from this and that and finally everything. Nope. She's dead, Jim.

While thinking about re-shuffling the parts, I realized I had an old mac mini in the closet, not doing much other than sharing music. MythTV on OS X said:

Frontend

To watch TV at acceptable speeds, you'll want at least an 800 MHz G4 or better.

Check... mine is a 1.42 GHz PowerPC G4.

And now a word from my technical reviewer:

If you've read this far, my 11 year old son, who reviewed this article for me, says you deserve a mini game:

Avalanche
Jump Little Guy! Jump and Be Free!

Now back to our saga...

I plugged it into a monitor and after a couple mis-fires, found a working copy of MythFrontend. Aha! Nifty! The front end mac mini is talking to the back-end on my beefy linux desktop.

Then I hit "watch TV." And... well...

The software clearly worked as designed, decoding and displaying video just as fast as it could. But the hardware was too slow by an order of magnitude, maybe two. I got about one frame per second.

With all the research I did on hardware for video capture, I missed the essential clue about playback:

To playback HDTV content, plan on a powerful CPU. "How powerful?" depends on a number of factors ...
The Simple Answer: Once you are in the 3.2 Ghz P4-class of CPU you should have no issues with viewing HDTV.
-- mythbuntu hardware wiki page

I suppose MythTV on old hardware made sense a few years ago for standard-def or even DVD content, but upgrading one of these old boxes for HD playback doesn't seem to make much sense when a new, quieter, low-power machine with native HDMI out like the Acer AspireRevo goes for around $350. That's just six months of saving$60/month that we were paying the cable company for TV.