Related link: http://www.oreillynet.com/pub/a/oreilly/digitalmedia/2004/10/14/digital_tv.html

Last September, I started using terrestrial digital TV as a program feed to my TiVo. I later described the setup in this article almost a year ago. Ever since the initial setup, my TiVo has worked flawlessly with the Hughes HTL-HD digital TV receiver. It cycles through inputs if it receives the same channel repeatedly, but it never missed a channel change command in a year. A large part of my research for the initial setup was devoted to finding a digital TV receiver that I could control over a serial connection from my TiVo. After getting it running in late September last year, I never had to touch it. The software started at version 4, and I’m not even sure how many times it was updated since then. The HTL-HD receiver just kept on chugging away, feeding my TiVo a flawless digital picture. As far as I can tell, the HTL-HD never missed a channel change fed to it over serial control.

Until this week, that is. All my recordings that took place after the early morning of August 17 were on the same channel. My TiVo had suddenly lost the ability to change channels on the receiver, after working so well for a year. As far as I can tell, the TiVo service pushed a new software version (7.2.0-oth-01-2-140) to me in the wee hours of the 17th.

It didn’t take long to diagnose the problem. When I changed the channel the TiVo thought it was tuned to, nothing happened on the HTL-HD. Whatever the TiVo had been doing to change channels, it no longer was.

First step: reset the HTL-HD, and see if it starts responding. Nope.

(It’s worth noting here that the HTL-HD is a DirecTV satellite receiver. DirecTV can push software updates to the receiver as part of the subscription, and software updates can change all sorts of things. I’m using the HTL-HD as a terrestrial receiver only, so DirecTV has no way of feeding me new software. It’s apparently somewhat common for new software updates to alter serial control capabilities. Since I have nothing connected to the satellite port, though, I can safely rule that out. Or start glowing in the dark, I guess.)

Second step: re-run the channel changing setup in TiVo. It’s very different from what it was a year ago. Last year, when I first set it up, you had to identify the type of serial control. Two protocols were in common use: MPG and APG. The HTL-HD uses APG. Those comfortable, familiar screens are gone, though. In its place, the TiVo now tries to guess what protocol to use, and those tests fail on my hardware. In the first test, the TiVo sends a channel change command. In the second step, you must reset the external receiver and try again. It doesn’t work.

I unplug both the satellite receiver and the TiVo, and try again. Still no luck.

Third step: re-run guided setup to be an antenna-only TiVo. Then re-run guided setup a second time to be antenna+satellite. This takes a great deal of time, and also does not work.

At this point, I just want my TiVo to change channels, so I dig out the infrared blasters from their original packing material. Changing the TiVo to use IR control for an external receiver is now different, too. There’s no longer a control code. The TiVo runs a bunch of experiments (”The TiVo tried to change to channel 2. Did it work?”), and I guess it deduces a code from that.

Infrared control has two major drawbacks. One, it’s much slower than the old serial system. If I move too quickly through the channels, say from channel 4 to channel 5, I wind up on channel 45. More ominously, the flakiness of IR that I was trying to avoid in the first place is readily observable. About half of the channel change operations have failed. When the TiVo tries to go to channel 20, it winds up on 2. Or channel 3 instead of channel 36.

This morning, I went to the TiVo web site for help. According to TiVo’s information, the latest released software for my Series2 is 7.1, but I have 7.2. The TiVo help forum this thread, dated August 15, says that version 7.2 is still beta software, and that it has leaked out to customers who aren’t supposed to get it. The initial poster even has the same problem I do–serial control of his external receiver quit working. A response on the thread advised calling TiVo support for help.

Given the paucity of information on version 7.2 (including the TiVo community, since a beta usually has non-disclosure rules), I decided to give TiVo a call to see if they could tell me why serial control quit working. Unfortunately, I didn’t get any help. I’m not sure that I got across the point that there was no software change to my HTL-HD. Although it’s a satellite receiver, I don’t have a satellite subscription, so I don’t get software updates. The rep I spoke with agreed that I shouldn’t really have 7.2, and I was part of his first look at the code. He insisted it was released code, but it was a mystery to him whether serial support was still in the code; he didn’t have access to any information about changes in the software. In the end, he wouldn’t admit that it was a bug, preferring instead to point a temporary finger at my serial cable. Until I buy a second serial cable at my own expense and try it out, apparently TiVo won’t admit that there might be a problem with their software.

Boo hiss, TiVo! I called with a very specific problem report, and got no help. It’s a good thing I have my MythTV box set up, so that it’s not particularly problematic that I can’t depend on my TiVo to record on the right channel.