Cello pickups
Well, I got my cello pickups, more or less put them together (selotape…) and borrowed (stole) a smallish guitar amp. It sounds pretty decent as a rock-distorted guitar, or like a bass guitar, depending on where I put the pickup and how I configure the amp. Pity I can’t get a decent acoustic cello sound out of it. Hopefully I’ll be able to whip out my soldering iron at some point and fix up the joints. Also a decent cable and preamp would probably help. If anybody knows anything about amping acoustic instruments or analog electronics and building a preamplifier, give me a shout.
Adventures with kexec
Filed under: Uncategorized | Tags: kexec frankenlaptop vaio bootcd initrd party hangover b
Comments(0)You may know, my laptop is in a rather horrible state - it has no harddisk, and the BIOS only boots off harddisks and CD-ROMs. It seems difficult/impossible to find a replacement harddisk due to the strange size and connector. So, I use a PCMCIA (PCCARD) CFCard adapter for a root filesystem and knocked together a boot CD for the kernel and initrd. In the initrd I wrote a custom linuxrc script to bootstrap PCMCIA, mount the root fs, and hand over to init.
The obvious problem with this solution is, every time I want to update the kernel or change a compiled in feature, I have to reburn the boot CD, which gets boring very quickly. I heard about something called “kexec” a while back, and suddenly realized this morning (While hung over after a party and having been woken up at 9AM to help with heavy lifting…) that kexec could solve a number of these problems.
What I do is, the boot CD loads up PCMCIA stuff, mounts the PCMCIA drive, then finds a new kernel and initrd and uses kexec to then boot that newer kernel and initrd. Therefore, all I need to do to update my kernel is copy the new kernel to /superduperbootcd on the root filesystem - dead easy.
There are a couple of drawbacks, mainly that going through two partial boot cycles takes a while, and any bugs in the kernel which appear during the first boot will need me to burn the boot CD again. But it’s still quite a neat solution, very cool, and a reason I love linux.
Speaking of bugs which appear during booting, occasionally my kernel segfaults on boot, before it even executes INIT - the backtrace mentions sony_laptop_init, or something similar. Has anybody heard of this bug, or know of a way to fix it? It seems more common when my power cable is not connected, but that could just be me.
(Waiting for my pickups from rapid….)
Cheers
Maplin update
Filed under: Uncategorized | Tags: cello pickups maplin money rapid
Comments(0)Well, maplin are still not sending me any stuff, but the money they charged has reappeared in my account, so I’m not too annoyed. I just reordered the bits I wanted from rapid (Great prices, great side, expensive delivery). I’ll update y’all once I get my bits and get some sound out of them. Anybody out there any good at electronics who wants to help me build a preamp of some variety, give me a shout.
Cheers
Why maplin sucks
Filed under: Uncategorized | Tags: Maplin suck money theivery cello pickups angry rant
Comments(3)So, I’ve been wanting to make some cello pickups for a while now, and I finally get off my ass (metaphorically) to get the bits to do it. I use maplin, as I quite like the look and feel of their website and they have the bits I want at a reasonable price.
I find all the bits I want and go to checkout. I create an account (they demand an easily guessable security question, I enter garbage, but that’s another rant). Finally I come to enter payment details. I enter all my card info (It’s a VISA connect debit card). They ask me for a maestro issue card even though I told them it’s not a maestro card, and ask for the start date which is never normally used for card validation on VISAs in my experience. I finish off the form and click order. Oops. ” Error 28. There was a problem attaining funds from your bank. Oh well, I try entering my card details again, thinking I typo’ed something. Oops - same error. Getting annoyed now, I try a third time, meticulously checking all details. Same error. A nagging feeling made me go and check my online banking balance. Now, I always keep a known small value in my debit card account precisely for this reason, so I notice if I get charged when I shouldn’t, and to limit my losses if someone nicks my card info. (I know a credit card would provide more safety, but I’m not elligible for one). Now here’s the problem: My bank balance equals the balance I always leave it at minus 3 times the total order value. So, Maplin showed an error claiming they failed to charge my card, when actually they took my money just fine and dandy. Also, the icing on the cake, my order does not appear in in the “Order history” section for my account on the maplin website. So, they took three times as much money as I told them to, told me they didn’t, and aren’t sending me anything in return.
Now I’m going to go and sit down and calm down a bit and see if I can get this sorted out tomorrow. Luckily the items I ordered were not terrifically expensive, but I would be in a serious mood if somebody stole this much money out of my wallet (Which is in essence what has happened).
Pimp My Music Stand
So, I was bored one Sunday afternoon and decided my music stand was boring. It’s a useful structure which is nearly always present when I’m playing the ‘cello, so why should it only hold music? Music stands can hold bows, but they have a tendancy to fall off, knock off the music, or other bad things. So, I began to customise.
Firstly, you will need:
So, the first feature I added was… (drumroll) The Bow Holder. This is very simple to do - take one unused pencil, pen or other straight object, and sticky tape it horizontally to the top of the stand. If done correctly, this does not interfere with the stand folding or music on it. The more tape used, and the tighter, the less the bow holder wobbles. Warning: If you generally have your music stand very low, as I do, the bow might hit the floor. Solution: Raise the music stand (or just let the bow rest on the floor).
After encountering problems with the bow falling off the holder when the stand is knocked or moved, I added an addition to the end - this small piece of [Pencil/Pen/knex/chopstick] goes perpendicular to the original holder, on the end. It being horizontal provides more security against the bow falling off, but makes taking the bow off a pain. If it is vertical, as mine is, the bow can simply be lifted (taking care to avoid mashing the hair). If horizontal, the bow must be angled then removed.
Secondly, the pencil holder - I simply rolled up some paper, added a lot of sticky tape, stuck more paper on the bottom, and taped it to the back of the music stand, at the top, in pride of place.
Lastly, the rosin holder - this depends on the shape of your rosin - mine is in a very nice round, metal tin. I made a paper cylinder with a bottom, and taped it to the bottom of the stand, with small nips out the edges to ease removal - it is a bit too tight, but you don’t want your rosin falling out.
No pictures, as my camera is dead (thanks to my antics with a screwdriver, but that’s another story for another blog - that and my antics with a soldering iron to try and resurrect it).
rectv
Filed under: Uncategorized | Tags: tv mplayer mencoder script bash hack
Comments(0)Here is a nice script I wrote, which I figured I’d share with the world - it’s for doing TV related stuff with just mplayer/mencoder rather than needing a special program (It could probably be done inside cron too):
#!/bin/bash mencoder tv://$1 -tv driver=v4l2:norm=PAL:quality=100:input=0 -of avi -ovc lavc -oac mp3lame -lavcopts vbitrate=10000 -o tv.`date +%S%M%H%d%m%y`.avi -ffourcc DX50
Nice, eh? This records the channel specified on the command-line on my tuner, which in my case is always 60 since that’s where sky is plugged in. It captures (not sure which codec it encodes with, probably some variety of mpeg4) to a file named from the current date and time to the current directory.
One thing I want to do is add an option so I can specify which sky channel it’s recording on the command line, and it’ll look up TV listings on the net and name the file after the program name. Heck, maybe even give it a beamer and let it control the sky box.
Any idea how exactly to get it to encode properly so my files aren’t massive and will play in a sane media player, please tell me. I suck at mencoder options.
Edit: I’ve recently figured out some encoding with lavc and mpeg4. The quality seems rather nice, and the file size isn’t /too/ massive. Also I figured out nice deinterlacing. Here is the updated script
mencoder tv://$1 -tv driver=v4l2:norm=PAL:quality=60:input=0 -of avi -ovc lavc -oac lavc -lavcopts vqscale=5 -o tv.`date +%S%M%H%d%m%y`.avi
And to play the videos with deinglacing I use:
mplayer -vf lavcdeint tv.<dateandtime>.avi
You can modify the original command to let you watch TV with mplayer too (can’t figure out deinterlacing with this one, lavcdeint only works when playing video, not live TV):
mplayer -tv driver=v4l2:norm=PAL:quality=60:input=0 tv://$1
Making your very own furby puppet!
Well, I was about to throw out a furby, but it seemed like a bit of a waste of some good design. So, I made a puppet! Warning, this almost certainly void’s your warranty and may (will) cause others to doubt your sanity.
Step one: Follow the instructions at http://www.phobe.com/furby/auto1.html to get the main skin off your furby.
Now you should have a creepy skeleton-style furby and a sockpuppet-style skin with a gaping hole where the face would be, and scrappy ears.
Step two: Reattach the other sides of the ears where the little bones used to go. The best way is probably with a needle and thread. (You could put in some more gadgetry here to let you waggle ears, but I decided not to.)
Step three: Disassemble the skeleton-furby as far as possible till the face part can be removed. I don’t have a clue how to do this, I just removed every screw I could see and eventually it fell apart.
Step four: Prepare the face for puppetry - I did this by using gobs of blue tac to hold certain bits of the eyes and mouth in place. Feel free to improvise for a wider range of furby facial expressions. I also added a largish gob of blue-tac to the mouth lever to weight it down, so the mouth closes when not held open.
Step five: Reattach the face to the puppet. There are black tabs on the faceplate which slot into two holes in the fuzzy bit holding the whole lot together rather securely.
And there you have it, your very own fuzzy gremlin-like puppet. Have fun, I’ll try to get some photos up sooner or (more likely) later.
OnSight
OnSight is my newest programming project. It is intended to help me practice sight reading - it is a small utility to generate random snippets of music - I got the idea off a website which offered a similar online tool, but theirs was only for treble clef and was not very customisable.
OnSight uses lilypond as the backend for generating music - it just spits out a temporary lilypond file and then executes lilypond. It is intended to be fully customisable - you can change the length of the snippet of music, the key signature, the time signature, the shortest interval of note it will generate, or all of those options can be randomised. It will then generate random music in the key and criteria selected.
Another planned option is random slurring of notes, which is common in most string music (Well, not random), and for more intensive practise, atonal music with no key signature, using random chromatics. Also, there will be an option to vary the range of the music, by selecting the highest and lowest notes generated, and possibly an option to focus the majority of the notes on higher or lower strings for more specific practicing.
Currently it’s just me working on this project, and I would welcome any other developers, testers, or help of any sort (I am pondering if it’s worth creating a sourceforge or other project hosting account for this).
Cheers
(Also, Edexcel, you suck. Look carefully at GCSE Music 2007 question 1, parts e and f I believe. :P)
“Linux is no good for gamers”
I just thought I’d go through a few things about gaming under linux. I recently built myself a new main gaming machine, with an AMD Athlon 64 3500+, gig of RAM, and an nVidia 7600GT XXX (Factory overclocked).
Linux support for this hardware has been brilliant - I have previously had to struggle with ATi binary drivers, and have found the nVidia ones to be so much better.
Once I got gaming, I was amazed by the performance. Playing at 1600×1200, with all settings at the highest, in UT2004 (Not the latest and most demanding game, but it could bring my old system to it’s knees at a higher resolution) and I was getting consistantly 200FPS at least on large outdoorish maps (CTF-FaceClassic). Now, what really amazed me was when I compared this to my friend’s results - he runs Windows XP (32 bit), has a gig of RAM, a dual core opteron (64 bit though the 32 bit OS…), and has the GeForce 7900 GLH (Goes Like Hell).
In pretty much every regard it appears his system should perform better than mine, but he gets a peak of 100FPS on most maps.
As far as I know the reasons for this probably are -
Also, enemy territory ran perfectly smoothly on 1600×1200, though I haven’t managed to benchmark it under windows on a similar system.
Now I await the release of Unreal Tournament 2007/3. From everything I have heard this will have full linux support (Hopefully UnrealEd will do linux too - previous versions need wine, not native), and should utilise my shiny new system.
Cheers.
A Ghosty Adventure
Or, “Why I use Linux”.
So, it started off the way any other good story does, I decided to backup my computer, popped out a Norton Ghost CD, and installed it. It all seemed very nice in windows, and the way it rebooted to the DOS part wasn’t too bad either.
That was, until I decided to boot back into normal computer mode. (Note how I avoid saying “Windows”). It turns out to boot into DOS mode, Ghost tried to overwrite both my windows partition MBR and my main harddisk MBR. So, to reinstall GRUB on my main harddisk MBR was dead easy - boot up a gentoo livecd, run grub-install, and I’m done. However, now I needed to reinstall my windows MBR. First I had to go and find an XP install CD. After finally getting into the recovery console, I realised it hadn’t detected my RAID. Then I had to go to the gigabyte website and download a floppy image, which for some reason was an EXE file. So I had to go find another windows computer to install the EXE onto a floppy, then get the XP installer to load the RAID drivers.
So, I finally get into the recovery console, and it has detected my windows partition. It asks for administrator password. Oops. After trying three passwords I thought it was, the installer decides to reboot my computer. So, in an attempt to try again with some other passwords, I boot back into the windows installer. But this time, the second I get to the recovery console, it reboots, instantly. Bugger.
So, after trying to reset the password a number of ways and failing, I give up. Gentoo and debian it is.
