vertical sync

Some time ago I briefly met a few engineers at a leading digital TV company and took the opportunity to ask them about my favorite topic, how they avoid sync problems in their set-top boxes (see many of my previous posts). It turned out that I had a hard time even explaining the issue to them and I realized that this is not something they think about a lot. Of course they use standard HDMI transmitters for the video output and are probably happy with whatever comes out. So I never really got an answer and I haven’t been able to find any through Google ever since. (And I’m not sure if Broadcom and the likes are interested in answering random questions without promises of future cash flow so I haven’t bothered to try.)

What I do know for a fact is that my own set-top box exhibits serious pan judder from time to time. I’m not sure about the exact source of this judder but since there aren’t any other artifacts in the picture, I suspect that it is the same old culprit as in the case of PCs, that the HDMI output isn’t synchronized to the incoming video from the satellite. Anyone out there working on HDMI transmitters who could enlighten me a bit about their inner workings?

I know I’m a bit of a nag but I do find the updates that I wrote about in my previous post both annoying and a bit amusing. Now I’m on vacation so this particular instance was perhaps more amusing than annoying.

I was happily eating my light lunch and watching a program from SVT Play (the Swedish Public Television on-line program archive) in full-screen mode. All of a sudden Firefox exits full-screen because it seems to think it is a wonderful time to offer me to update the application. And it actually looks like Windows 7 takes the opportunity to throw some updates at me while it has my attention. Imagine if my car did that while I was overtaking a truck. Of if I needed to make an urgent call with my cell phone and it started updating an application and asked me to kindly wait. Like Frankie Goes to Hollywood puts it: there’s gotta be a better way! (Like making the applications safe in the first place.)

Bad timing. I was watching an interview with Ian Gillan.

Welcome to my HTPC!

I installed Windows 7 on my new HTPC since XP seems to be singing it’s last verse. The sad thing is that I totally fail to see the value of the upgrade. It actually made things worse:

• Once I get video to play, the video quality is no better than on XP. The built-in decoder DMOs seem to have timing issues too increasing the risk for stutter.
• I can no longer choose filters for my GothPlayer using the merit system (or any other system for that matter) and sound doesn’t work with some video formats (e.g. AVCHD). There is an open source utility for selecting filters that works so and so but Microsoft has decided to force its users to use its own filters.
• Many of the default update rules actually wake up the computer from sleep and don’t shut it down again. I have found the computer humming many mornings. It’s been a pain to go though all the scheduled tasks to try to find what’s waking up my computer.
• I might be imagining but there are a lot of updates. So typically when I fire up the computer to watch a movie I end up baby-sitting an update instead and that update invariably eventually wants to restart my computer.

I start losing my faith in the whole concept of an HTPC. I feel patronized by all the stuff that I must do just be able to play some movies with the apps and decoders of my choice. And I feel cheated having paid positive money for a W7 license in exchange for negative value. Maybe I’m just a grumpy old man but I’m off to scan the market for a good Blu-ray player with its software in a ROM.

Links

I’m not alone complaining about the missing filter merit system. See for instance this post.

I think I got the Swedish movie on demand service Voddler to work for a short while on one of my computers since my last post on this topic. Today I tried it on my HTPC. I get two green check-marks when starting up Voddler. Then it hangs for at least five minutes setting up one thing or another. I get impatient and I click around a bit and hit the “force playback” option. I get about 10 opportunities to accept the license agreement for the Adobe player. I see the start of a jerky commercial. And then some more license agreements. I think I prefer the GNU licence of the previous client. I give up again. Perhaps I will give it yet another try in a few months’ time.

I use SVT Play, the Swedish public service channel’s Internet service, quite often to catch up with some of my favorite TV shows. The user Interface is excellent. You point at a show in a nice looking browser, you click and the video starts playing right there in Firefox. Usually I get interrupt-free playback and reasonable video quality. The encoding is a little leaner than that of Voddler but that’s the only difference I think.

How hard can it be?

I got my image back with an old 6600GT card. Noisy but works fine. That’s the good thing.

The bad thing is that the behavior of my app can not be explained by a driver bug. It is perfectly repeatable with an NVidia card. It appears both in debug builds and in release builds which means that it is probably not just a spurious memory allocation problem or something like that. I have to get used to the thought that it might be a real programmer mistake, as tough as that is.

Just to keep the perspective, I have to remind myself that everything I write about are problems of the industrialized world and therefore – really – not problems at all. But I think it is fair to say that I’ve never had a problem-free upgrade of an ATI driver – ever.

I decided to upgrade the driver on my development machine. The bug I’m chasing might, I say just might, be a driver bug. It appears when going from exclusive mode full-screen to windowed mode, but only the first time, and only when using the second monitor. Everything works fine the second time I toggle between exclusive mode full-screen and windowed mode on the second monitor and it always works on the primary monitor.

Anyway, after upgrade, the computer went totally black. I have a spare NVidia board in the closet and I think this might just be a good time to bring it out and give it a spin. All my NVidia upgrades have been painless as far as I can remember.

I guess I was barking up the wrong tree in the previous post. I’ve learnt that S1 sleep is indeed supposed to leave the CPU and the fans on. I was most likely using S3 on my previous HTPC, not S1 as I initially thought. I thought it must have been S1 since S3 takes so long to resume from on the new HTPC. But the error is not always where you are looking.

As i mentioned i also have a problem with the power supply. The symptom is that it takes several attempts to start the computer. But on one lucky occasion it started on the first attempt. At that particular occasion it only took a few seconds to get back to the login screen from S3 (as opposed to over a minute in most cases). So potentially it wakes up as fast as my old HTPC, just not everytime.

My hypothesis is thus as follows: The failed start attempts corrupt the state in the memory which makes the computer revert to the state stored on HD (I think one of the features of S3 is that it stores the state both on the HD and in the memory). Resuming from HD is more time consuming than resuming from memory obviously.

So what initially looked like two different problems was probably only one. Still waiting for that new PSU…

It’s Christmas day. The family dinner was on Christmas Eve so it has been a very peaceful day with time to put together the stack of stuff depicted in this post. I purchased a copy of Windows 7 Home Edition to the stack for a complete new HTPC. Here are a few snapshots of the assembly:

Life is like an empty box…	Who comes up with these ridiculous names? “Memory lover!”. That doesn’t sound like a motherboard for real men. Well, the specs looked right.
It’s so fun to put things together so I often do it twice. Having fastened the motherboard with all 9 screws I realized that the fan backplate needed to go under the board (“backplate” should have rung a bell). I decided to install the fan with the motherboard out of the cabinet. It was easy enough.	The fan fit into the cabinet with a 5 mm margin. I will not install any cabinet fans to start with. Hopefully the CPU fan will keep the air moving fast enough. I’m a bit worried about the GPU as the GPU heat sink and the CPU fan are on opposite sides of the graphics PCB. I need to keep an eye on the GPU temp for a while.
Most of the stuff fit in. I didn’t want to install the digital TV tuner as its slot was next to the slot of the graphics board and it would have covered the GPU heat sink. There are a lot of empty slots further away but of the wrong kind. This I think is an example of poor design as many high-end graphics boards actually require two slots, whether for a big fan or for a heat sink.	My home burnt Windows DVD seems to work (I always use the Linux application Brasero to burn my DVDs including ISO images).
I agree, I guess…	The SilverStone cabinet gives good value and looks for the money. The Blu-ray/DVD drive lid doesn’t work perfectly but maybe it just needs to be broke in a bit.

There were some glitches:

• You still can’t buy stuff from Microsoft through a Swedish site. Clicking “Köp nu” (Buy now) on the Swedish Microsoft site takes you to the US site where you are required to enter a state (but no country) in your address. After some confusion I found the UK on-line store where I was finally able to purchase a copy of the home edition of Windows 7. I’ll spare you the obvious comparison with the ease of getting Linux.
• There was no way of telling from the mother board documentation which way to connect + and – from the power led and the HD led. I got the HD led right – and the power led wrong.
• The default sleep mode (S1) leaves the CPU fan on (and maybe some other things as well). What kind of sleep is that? I’ve seen this behavior on some older computers I’ve had too, but not with boards from ASUS. The next motherboard will probably be an ASUS again. Or else I should avoid Corsair power supplies.
• The power-on button often requires multiple pushes for the computer to wake up. The board gets powered up for a fraction of a second at the failed attempts but then dies again. I will try to find out if there is a pattern.
• The lid over the optical drive doesn’t open as it should. It gets slightly stuck in a semi-closed position. This seems to be a result of a bad fit.