Fighting with computers

Computers are not always friendly.

Wednesday, April 26, 2006

JPEG and Wavelets


I'm teaching a course on Multimedia Data Transmission and I had to give a couple of lectures on image encoding. So I had to attempt to build some understanding on how several standards work and their underlying math. As you are probably aware, JPEG standard allows you to encode continuous-tone images (photographs) with a typical reduction of 1:20 on the storage needs over other non-lossy methods. JPEG is based on the use of the Discrete Cosine Transform (DCT) that [basically] translates image spatial information to the frequency domain, where the weaker higher-frequency components can be removed without that being too noticeable.
JPEG 2000, on the other hand, is another image encoding standard based on the wavelet transform instead of DCT. Wavelets are families of functions that allow multirate analysis of signals. And here you will find the best tutorial on the subject I have found on the web. The end result is that wavelet-based image compression provides a smoother image than DCT-based ones for the same data rate. However, if compression is not extreme it is not so easy to tell when each one if used. So bottom-line is that most products for the moment do not use or support JPEG 2000 (which is not patent-free).

Thursday, April 20, 2006

Kind of fixed

After returning the CM Media 260 to the guys at Wikidi (that were quite nice with the return). I tried, again unsucessfully, to recycle an old Samsung DVD but unfortunately it was not large enough for all the stuff to fit in. So I went back to what I could find around and I bought, for the second time from the same seller, an Antler DM-318 case that seems to be a clone of Antec Minuet II case but with a distinct front plastic piece.

This first image shows the original inside of the box. After several attempts and given the case only accepts low-profile PCI cards I "borrowed" the dual PCI riser card from my Pundit case: It didn't work, as none of the two TV cards were detected. Anyway, it was impossible to fit that in. So I went to an extreme solution. I put a sheet of 3mm Depron on the bottom of the box. I removed everything and I started from scratch. The new photo shows the end result.

Unfortunately, right now everything is just laying on top of the Depron sheet without any screw but it works and it fits in. Of course the back of the case is a mess as the ATX window to get all the connections out of the motherboard is off almost two inches. I guess if I can find a reverse PCI riser of the proper height I could get the motherboard to its proper position and also the power supply. But for the moment I have a working solution using a PCI riser from a Supermicro 1U computer. I have had to forget about the analog TV tuner and I am only keeping the Hauppauge DVB-S card.

The front of the box is redish black but it is not infrared friendly so drilled a small hole and I stuck the IR receiver on the front. It does not look bad and it is now more or less quiet; I needed to reduce the voltage of the power supply fan to 7 volts (connected between the +12v and +5v terminals) and so I did with the other fan that right now is actually outside the box to get the warm air out of my TV cabinet (which is closed on the back). So this is the last word of warning: Even if your case has the proper thermal desing; it might not work on some of the available furniture that is not designed with the idea of having that amount of heat in there.

For the moment I am more than tired about this [apparently] simple project of replacing an old and trusty case with a new stylish one.

Monday, April 10, 2006

Back to square one

I've been told I need to buy riser cards as an add-on for the box I bought. Unfortunately the cost of the box is already well beyond the cost I was willing to spend on this particular item. I'm not 100% sure it is not my fault, but I did not get that impression when reading the manufacturers specifications. What I understood was that you may buy AGP or PCI-express riser cards. Now I guess any of them also comes with a double PCI riser card.

At any rate, I think I am going to recycle that old DVD player I no longer use and it is sitting in a cupboard and I am returning CM Media 260 box to the retailer. Let's see how this refurbishing project goes.

Saturday, April 08, 2006

Buying a slim PC box is not that easy


I've got my new box on Friday. The company I bought it from did a good job at delivering on time but all what happened next has been a mess.

Firstly, when I open the box I discover the color is black and not the silver I have ordered. Not good, I emailed my supplier and they reach me on the cellphone to apologise and to offer me a replacement but not sooner than next week. I thought about it and finally I decided I would be keeping the box after all, just for the sake of getting the system rebuilt over the weekend.

Saturday, early in the morning, I start the process of disassembling the old beige-box components of my PVR. When I am done (and a bit dirty as you know how the inside of a computer is), I unpack the CM Media 260 black box to start building the new system. Manufacturer's instructions ask you to disassemble almost everything first and so do I. I assemble the power supply (not without removing some screws from the power supply to have a smooth top surface). I then place the motherboard and I fix it. And then, where is the PCI raiser card? ... There is not one.

Ok, this is just too much, I cannot build a working system with that. Both tuner cards need to be attached to the system to have any use of it (actually I am not using VGA output). The shop is now closed so they do not answer my calls and email is waiting somewhere in their inbox.

I do not know exactly what to do now, so I rebuild the old system with a cleaner inside now. So, after $200 and two hours I am back to where I was before: I still need a box. Let's see what happens next.

Bu the way, I failed to mention that more than a year ago I bought an Asus Pundit barebone for the same purpose but I had to return it as the DVB card did not fit in. So by now I have bought three different boxes but the system is still inside the ugly mini tower beige box.

Copyright infringement and fair use

Apparently, lawyers at YouTube are not aware of what fair use is. I've just got a copyright infringement notice about the video I posted yesterday that was a 38 seconds excerpt of a >1500 seconds show. And that just because they were using my name, without my permission :-)

Ok. I do not think this issue deserves more brains or more of my time.

Tuesday, April 04, 2006

Buying a PC box for the living room


It is not rocket science, you say. It is not, I do agree, but forget about getting it solved quickly once you do not want whatever they have to sell you. I just wanted to get an empty box that would fit in my TV table. My current TV computer uses a standard mid-tower beige-box. My only limitation was that I needed a box not taller than 14cm, but I had up to 50 cm width. It should be enough.... wrong!

The first box I bought was a new brand, Antler, a Poland-based company. The product was nice and well priced but I had a problem: It only accepted low-profile PCI cards and I needed one full size PCI slot. I went back to the web and I found this nice article. Thanks to them I could narrow down my choices to a couple of boxes only: Siverstone LC11 or CoolerMaster Media 260. The last one does not come with a power supply so it could be cheaper, or so I thought.

Unfortunately for CoolerMaster, the only partner they have in Spain that seems to sell retail is the Beep.es chain. It took them one week to email back just to tell I could not get a quote online and I needed to go to the shop in my city to get that information. I phoned three different shops, only one answered the phone, I asked them for a quote and availability of CM Media 260 but as time of this writing I'm still waiting for their answer (Beep Ruzafa, in case you ask).

Google use to be my friend when searching for a product, but it failed me in this case. I could find only a few shops that claimed to have the product. Given my lack of success with traditional shopping I decided to shop online. But, again, I faced the problem the box is only sold --apparently, because another mail to CoolerMaster Europe got unanswered, too-- with a remote control and vacuum fluorescent alpanumeric display. At least it works with Linux as I could check with LCDd project. But the bottom line is that I ended up shelling out around $180 for the thing (you can buy it for $90 on eBay in the USA). And please note this does not include a power supply.

At least I hope that the craftmanship will be on par with the price. If I am lucky I'll get the box on Friday so I could conduct my weekend's cursing ritual (while building the system). Still, it is cheap when you compare it with the >$1,000 new Fujitsu media centers.

Update: I've just get an answer from the Beep franchise shop. They are unable to sell me any version of RC-260. This really makes you wonder why they are on the list of CoolerMaster distributors in Spain on CoolerMaster website, also marked as having stock.