Software-based matrix switcher?

Today I discovered two new libraries/applications:

  • Festival (text-to-speech engine)
  • PulseAudio (distributed cross-platform feature-packed sound daemon)

This has opened up a whole new realm of possibilities. Rather than paying out £400+ for an A/V matrix switcher, PulseAudio may allow everything to be done through a combination of software and soundcards. If I understand it correctly, the audio sources could be anywhere in the house (via a nearby networked computer with soundcard) and the sinks (amps, speakers, recorders etc.) can be elsewhere in the house (also connected to a nearby computer). The network carries the audio over IP and PulseAudio does all the funky stuff.

Combine this with the text-to-speech features of festival and you’d also have a talking house. This isn’t a new idea – many home-brew home automators have added TTS facilities to their houses – but it’s an interesting one. While it wouldn’t be used for frequent announcements, urgent announcements could be broadcast. If I can get the alarm system connected to the network, it could shout out messages to intruders. If a CO or smoke detector is triggered, the voice system could relay the message to all rooms in the house.

Ubuntu as a media centre PC

A little over two weeks ago I ordered a new computer from EfficientPC. They appear to be the only independent business selling true linux-based machines. Anyway, what I was after was a box that could run MythTV reliably but quietly (since it will be in the living room).

At our previous house I tried to set up Boron as the machine for this job, since we had the space under the TV (though I had to take a jigsaw to the back of the cabinet) and it was the only suitable machine for the job at the time. Our huge and heavy CRT (now retired to the master bedroom) has component input, so I tried several DVI to component converters that supposedly worked on the Radeon 9600 that sits inside Boron. As these things always go, it didn’t work. So now that we have a TFT TV with VGA input, I have another chance to get a fully-functional media server set up.

This new machine is pretty much silent – certainly quiet enough to sit in the living room, behind the TV (it’s also very slim). I’ve also discovered that it’s pretty nippy, sporting an Intel Core 2 Duo E2140 with just 512MB of DDR2 (since there doesnt need to be a huge amount of RAM for a media centre – processing power is more important). The 500 GB drive should give a few hundred hours of recording capacity. It has been called Sodium, because I try to go for things that are orangey with the Ubunto machines – sodium lamps shine orange – and it will be the ‘Master Backend’ server for MythTV. Boron will be a slave server, and there will be various front-ends around the house.

I found out after ordering this new Asus Camulus-based computer that EfficientPC is run by a single person, so service is not speedy. He is apparently struggling to keep up with demand, so emails often go unanswered. I am not bothered by this, and the quality of the product is pretty good. This guy makes sure that the hardware that he provides works with Ubuntu, which provides more peace-of-mind than if I would have ordered the parts myself then found out that they don’t work under linux.

The only problem, other than breaking a PSU, is that the PCI DVB-T tuner cards that I have will not fit inside the Isis case. I’ve ordered a Nova-T 500 dual tuner card to compensate (along side the replacement PSU and another 500 GB drive). The beauty of MythTV is that it will allow me to use all of the cards in separate machines, combined into one set of recordings that can be watched through any of the MythTV front-ends in the house. So that’s 4 tuners allowing 4 shows to be recorded simultaneously. Eventually this may be expanded to include satellite tuners because we have a very weak digital signal around here. More on the specifics of MythTV and how it’s being set up in our house soon.

There will be photos shortly, once I’ve got the system fully set up.

Beware of air dusters

I’m not having a very good week when it comes to breaking stuff. While removing two tuner cards from boron for the fantastic new pc for the living room (details coming soon) I decided to blow some of the dust away with a can of compressed air. It certainly did the job, but when I plugged the power back in nothing happened. I suspect that when I cleaned out the power supply, the very cold air coming from the can (since gasses cool as they expand) caused one of the components to experience thermal shock thus causing it to fail. So a new power supply is on order, and I’m hoping it will arrive tomorrow though I’ve not had a despatch notice from Dabs yet. In the meantime I’ve found an old PSU that used to be inside aluminium, but was replaced because it sounds like it’s arcing, so to avoid a fire caused by that PSU boron is currently switched off.

Moral of the story: don’t air-dust warm components.

Back to the drawing board

The test of the audio matrix switcher prototype has failed on two fronts:

  1. the multiplexers refused to work
  2. the amplifier exploded

Of the two problems, the second is clearly the worst because it’s cost me a £50 amplifier. It may be repairable (sounded and smells like a capacitor exploding) but I’m not going to assume that it is. Since the multiplexer didn’t work as I had hoped, another approach to the audio routing needs to be sought. I’ve contemplated buying a commercial product, and a quick look on eBay finds some A/V switchers with RS232 support for £350-£500. Getting one of these would have the advantage of being able to route video signals too. Of course the disadvantage is that it will be significantly more expensive than I had planned on. Remember, on top of the cost of the switcher will be the cost of 4 stereo rack-mountable amplifiers at about £50 each.

So not a great end to an otherwise highly productive weekend. I have managed to get more of the rack cabinet finished (added the locks), tidied up a bit and got mvpmc working.

mvpmc and Fedora

I’m really starting to dislike Fedora. It’s bloated and breaks so easily. Unfortunately it currently runs my primary server which hosts DNS, DHCP, SMB and OpenVPN server.

A few weeks ago I finally found my MediaMVP box hidden away in one of the draws in my bed. I’ve used it before to run mvpmc, a client for the MediaMVP which presents a simplified MythTV front-end. This was back on FC4 i think (maybe FC5). Now I’m using FC7 but I’ve discovered, after a lot of pain, that the default DHCP server in Fedora does not work with mvpmc. I don’t know and don’t care why it doesn’t work, but at least I’ve now got a successful DHCP server running on my Unbuntu system – only problem is that system is only on occaisionally. If I can get VMWare Server running on boron though, I can get an Ubuntu VM set up purely to run the DHCP server until I can get around to completely replacing Fedora with the more fashionable (and much more reliable) distro.

So a note to people wanting to boot mvpmc: don’t use Fedora to host your DHCP/TFTP servers.

Another note: there’s a new version out (after 10 months of waiting!).

If you’re interested in open-source media centres, I’m intending to write an article about MythTV and mvpmc, with reference to how it’s being set up in our house.

Wiring the house


Before we moved into our new house, I lifted some of the carpets and floorboards and installed some runs of cat5 and speaker cable. In total there are 24 cat5 cables and 4 pairs of speaker cable. I’m not sure the length of network cable that was used, but a rough estimate is 400m – not quite as impressive as some other installations I’ve seen details of, but it’s a fair amount to pull on your own! I know exactly how much speaker cable was used though, because I used the whole reel – 100m.

Continue reading “Wiring the house”

Audio Distribution System – Phase 1 – The prototype


This project is intended to investigate the possibility of, and hopefully build if successful, a home-made externally-controllable matrix switcher with 8 inputs and 4 outputs using parts that cost a total of < £100 (excluding the external equipment such as amplifiers, speakers and cabling). The quality of the audio must be acceptable, but I'm not expecting it to be perfect - that's why the expensive matrix switchers exist. It just needs to serve the purposes of a small house. Continue reading “Audio Distribution System – Phase 1 – The prototype”

Project Names

I have currently have a two different naming schemes in use, to identify my various computers and networks. My home network is called ‘elemental’, and each node attached to the network that has an IP has a name taken from the periodic table of elements. The computer I’m typing this on at the moment is called ‘aluminium’ … because it’s got an alumimium case. My external severs are under the ‘sol’ network, which currently only has one node called ‘earth’.

Now I’ve had the idea of naming my various projects. I just need to come up with a naming scheme. Maybe subatomic particles? There are enough of those to keep me going for a while, especially once CERN get the LHC (what a lovely retro site) experiment running. Let’s try that:

  • Project Electron – The rack cabinet (contains most of the other projects)
  • Project Gluon – Cat5 wiring (holds stuff together, in a network sense)
  • Project Quark – Audio distribution system (Quark in DS9 is a Ferrenghi … has big ears … can hear well …)
  • Project Proton – Security & surveilance (can’t think of an excuse)
  • Project Neutron – MythTV install

Of course, unless I’m going to name things after various versions of some of the particles (up quark, down quark etc.), it is actually quite limited for the time being. And not being a physicist (beyond A-level) doesnt help.

I can’t think of any other schemes at the moment.

Hmm, this has turned into quite a monologue. I think I’ll shelve the idea for the time being, unless someone can come up with better suggestions.

DUOS posters

DUOS approached me several months ago and asked me to produce a poster for a concert in Durham Cathedral. Apparently they liked it so much that they’ve come back and asked me to do 2 more for some concerts in December 🙂 I’m not a professional designer, but it’s nice to have a go at designing something that’s not a website.

The first poster:

DUOS Poster - 17th June 2007

This design was based around the theme of the main piece of the concert – death’s fiddle striking up.

First design for concert on 1st December:

DUOS Poster - 1st December 2007 (Version 1)

This one was inspired by the only reasonable artwork I could find for one of the pieces. The original was landscape, so I had to take some liberties with Photoshop and apply it over the top of a photo. While the result was ok, it wasn’t particularly easy to read and was very busy. This design was dropped in favour of the one below.

Second design for concert on 1st December:

DUOS Poster - 1st December 2007 (Version 2)

Much simpler, going back to the violin cliché. It does the job.

Poster for concert on 6th December:

DUOS Poster - 9th December 2007
This one was inspired by a tutorial, although I didnt follow it to the letter. I’m afraid I can’t lay my hands on the link at the moment, but I StumbleUpon’d it, so click that Stumble button a few times and you might find it!

My DIY 19″ Rack

The (almost) completed rackThis project started off as being a cheap way to have a 19″ rack in which to mount my growing amount of equipment and future projects. It turned out to not be as cheap as I’d hoped, and it’s taken several months of intermittent work to (almost) complete, but I’m pleased with the results.

There are still a few finishing touches to be done, such as adding the top, adding the lock to the rear, mounting the new bolts to the front door, cutting out the bottom ventilation hole and adding some fans. Future modifications could include adding lighting and environmental monitoring/control.

Below is a photo log showing how it was done.

Continue reading “My DIY 19″ Rack”