Fighting with computers

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 tha...

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 witho...

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.

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 pla...

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.

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 o...

Recently, I was involved in a development where remote access to a serial port was required. I was doing my development with a Rabbit core and I needed to get Internet access to a serial device and to simulate a serial port on the host PC. I learned that you could use RFC-2217 which is an extension to the telnet protocol. I went to nabble to get some help but I found out nobody seemed knowledgeable about that protocol. So I did my job, and when I got it running I wrote an article for an engineers magazine. Once I get the "go" from the editor I'll let you know where it is published. I used with quite success Fabula Tech's Serial Port Redirector which is RFC-2217 compatible, but it is not free. For a free redirector you could use HW-group's Virtual Serial Port but be warned this latter software does not handle break signal generation. The same thing applies to Digi One SP device that, although the manufacturer claims it to be RFC-2217 compatible, it is not ca...

I was approached by a lawyer whose client was an employee fired for porn surfing. The company threw some logs at the employee as a proof of his wrongdoing. However, the employee rejected these claims as erroneous and sued the company to get his job back. I was asked to double check what those logs really showed. Just to play safe, I decided to conduct my "research" from my home network instead of my employer's network. What I learned was somehow baffling, as most of the logs appeared incomplete showing only one small gif or jpeg per site with almost no html pages visited. While some of the images had some sex contents most didn't. Still, the names of the servers talked by themselves about the contents of those sites. Multiple visits to the same gifs suggests no caching on the browser, or ..., multiple clients. It reminds me the Migmaf trojan but that was way back in 2003. Unless I get access to the employee's computer I cannot make a better judgement now. At any r...

I did it again: I fell for another new toy. This time the winner was the inexpensive Acer 3002 WTMi that packs quite a decent feature set into a small size and weight. I won't bore you with the details, but have a look a it if you're planning to buy a light small form laptop . It comes with WinXP Home Edition installed and, as usual, you'll have a hard time if you try to get a refund on it. Microsoft's tax seems to be a burden if you buy a laptop either you like it or not. Although I've installed SuSE Linux 10.0 I'm not very happy with the results for the moment. First of all you need not to use APIC for the installation to start. The system installed very quickly and it did one of my FAT32 partitions to shrink without any problem. It took less than 15 minutes to get the install finished. What I've got working are graphics, WiFi, Bluetooth, Ethernet, DVD-RW and synaptics mouse (the latter even better than with Windows) but sound is missing (it looks like an...

Dealing with software you cannot change is a risky business. This time I need to emulate a serial communication to fool the software to think it is talking to a directly connected device. I have tested several serial port emulation software with not much luck. However I have to tell you the guys at Fabula Tech have a winner with their Network Serial Port Kit . It worked like a charm, providing a way of sharing a serial port on one computer so a second computer could use it remotely through a network connection. Not only this, but these guys have a fantastic on-line support chat that, contrary to most of them nowadays, they are knowledgeable and they solved my problem at the first shot. Really recomended product and service. However, I needed a solution I could throw at a client's computer even without network card. I looked around for serial device servers and Digi One SP looked a good choice. I bought a couple of units to see if they could really replace a serial cable (you repla...

I've learned about an interesting site on the net: Cosmopod.com What is it about? In a nutshell Cosmopod offers you a free remote KDE desktop, either using a Java-based client software or the (also free) nxclient software. I do not know how reliable the service will be in the long run, but my initial tests are very good. Although services like writely seem promising, I'm really impressed with Cosmopod. They also offer a 1GB email account with your desktop. You may like it, I do.

One of my current projects requires to provide IP connectivity for an electronic system. Some power can be borrowed from the base system it will be plugged into. A small, low-power system will do it. So after considering several options (like Lantronix Xport ) and provided I needed at least two serial ports, I settled with a Rabbit Semiconductor core module. They offer different prebuilt cards you can plug into your design. Rabbit core modules can be programmed using Dynamic C . They include a TCP/IP library so you can program them using an ad-hoc sockets interface. Sample source code is provided and it generally is quite straight forward. I did have a problem when using a non specified (zero) source port for several destination ports different than 80 or 23, I do not know why. Rabbit 2000 and 3000 processors are both successors of the ancient Z80 , an eight-bit microprocessor developed by Zilog (a company founded by some former Intel engineers that decided to do a better 8080). Z80 w...

I've never heard about a "flash sale" before, but recently I saw an ad on a local retailer's website offering a cute Toshiba laptop (M50-137) for a really low price only if you buy it on December 23rd. They take 200 Euro off the list price of 1200 Euro. I thought it was making it sweet. The system was a 1.7 Ghz Pentium M, with a WXGA Ultrabrite 14" display, 1GB RAM, 80GB HD, Wifi+Bluetooth, built-in SD-card reader, and a multistandard optical unit (DVD+-RW/DVD-RAM) weighting 2.4Kg. I took the deal and I picked it up at the local store. It took them longer than the advertised delivery time but eventually I got it home. First impression was good, system was fast and quiet. Sorry, you cannot get along without accepting the Windows blue thing: You have to provide some user and location data so Windows gets happily installed. Till you do this, SuSE Linux repartitioning failed to work. After that, I successfully installed SuSE Linux 10.0 and it almost worked fully. I ...

I was recently approached by a company willing to give new life to old security equipment. The system had a proprietary serial bus, but the manufacturer refused to disclose any information about it. Provided it was more than twenty years old it should not be a big challenge. However, figuring out the details of a serial communication you know nothing about will require some nice tools. This time I bought a nice USB oscilloscope . It's only 1 Mhz bandwith but fast enough for my needs in this case. With it I was able to capture bidirectional communication (as it is dual channel) and start the process of figuring it out. Just looking at the scope signals will tell you the encoding and bitrate (look for the shortest pulses, they are likely single bits and its time-length will tell you the bitrate). Serial communication used to be mostly asyncrhonous, and this was also the case. Once the time duration of a bit known you can figure out the data length and wether parity is being used or ...

I've just installed in a couple of systems I use. I decided not to do an upgrade from previous versions. It's nice you can use /home partition from a previous install so you can keep all your bookmarks and email and documents without too much trouble. A bit disappointing is that, still, java applets look bad (due to huge fonts) and that it cannot play almost any media file out of the box. But here is the cure . As for the rest, the system seems to be quite fast and stable. However, it will not be until some weeks have passed that we may have an informed opinion about this release stability.

Every time I build a new computer or I rebuild and old one I run into trouble. This time I transfer my old computer to one of my children and I bought a new ASUS Pundit-R with the cheapest Celeron I could find (a 2.4GHz one). Because my kid wanted to play games I replaced the ATI Rage 128 16MB RAM with a NVIDIA 440MX 64MB RAM I had lying on the drawer. However, I needed to get a new fan before as the old one on the card was making a lot of noise. Once the installation blues was over and the kid started playing he came back telling me that the system was freezing. A quick check-up showed the new fan was not properly fitted, so I removed the card and I re-attached the new fan (with funny LED's by the way). Minutes later, same problem. Ok, over time I've developed the attitude that the best brand of hardware is "brand-new". I was not 100% sure the card was ok so I went to the shop and I bought a non-NVIDIA graphics card. This time it was an ATI Radeon 9250 128MB RAM and ...

I've been using MPlayer quite extensively since I built my digital satellite receiver two years ago. I use MPlayer to play AVI/MPEG/MPEG2/OGM video files and I use MEncoder to actually create such files from MPEG2 broadcasted shows. These command-line tools that are both great and free software. Tools are based on standard video codecs and there is even support for commercial codecs (provided you get their dll files). I've used MPlayer on Windows, Linux and OSX without any problem. If you are a perfectionist a great deal of fine tuning of codecs parameters is possible. If you are "good enough" guy (as I am) you'll be pleased with default behavior most of the time (both in terms of computing speed and output quality). MPlayer is a program to play video/audio files that can also dump audio to a file. MEncoder allows you almost any transformation of your multimedia files (video+audio) plus different filtering options and limited stream cutting. My main use is to rec...

This distribution is available on ftp.suse.com for a month or so. You can dowload the installation DVD or you can do an FTP-based install by booting your computer with a small (60MB) ISO image. I've been using SuSE for three years now and I am, most of the time, quite pleased with it. It is my main distro and I like to have DVD full of software I can install without having an Internet connection. I do like the online update feature too. I have been upgrading my systems every now and then, mostly because newer KDE versions use to inlcude lots of fixes and new cool features. But when I tried 9.2 to install in my trusty but old Toshiba Satellite (128MB RAM only) it took around 6 hours. Afterwards the system took, everytime, a lot of time to boot because it froze for a long while on udev. And when it booted KDE was almost useless as it was slow to a crawl. The system was still acceptable, but slow, on SuSE 9.1. Because I had an Ubuntu install CD around I used this instead and now my ol...

After five years of trouble-free operation with my 11Mbps D-link DWL1000-AP 802.11b wireless access point I decided to upgrade my home wireless gear. The USRobotics USR-8000A router with print server and the access point were replaced by an SMC2804WBRP-G that contains a print server (for USB printers), 54Mbps 802.11g wireless access point, four ports FastEthernet switch and router, all in one nice box. My initial research on the net told me the product firmware was quite poor, with lots of users reporting different problems. However, because the retail price was under 100 Euros I decided to give it a try. The results: I configured the router off-line and then I just switched the old by the new gear on the fly. The p2p software I was running on a server continued running as happy as before. I was a bit dissapointed as the unit's current firmware does not provide fixed IP mapping, this can be a problem. After some hours of happy networking my son complained an streamed sh...

These holidays we've got some new stuff to play with. I'm very impressed with the new Creative Zen Micro , which is a harddisk based 5GB MP3 player plus FM radio plus voice recorder. It looks cool, it sounds superb and the software just works. Very nice too is the new Muvo (same capabilities but Flash-memory based, ours is only 256 MB). But the star has been the PB1600 video projector. It really delivers a great image for either DVD or VGA. It's 800x600 DLP-based but our 1024x768 iBook displays just fine. Now I need to get a projection screen to get the best result.