More people should know about "Cleanfeed"

Cleanfeed is an internet site blocking software used by BT and other ISPs to mask out web sites in UK. It was started by BT in 2004 and extended to other ISPs in 2007.

It allows the Internet Watch Foundation (find them here) to collect complaints and pass these to the ISPs who then block access to the web sites. Typically this means blocking child sex abuse, obscene material and racial hatred sites.

New attack by MPAA

Enter the MPA, an international arm of the USA MPAA representing the movie studios. In june 2011 they took BT to court to try to get sites hosting or indexing copyright infringing files - movies etc - blocked. Specifically they are targeting a site called Newzbin which indexes the files on the internet Usenet system. Many copyright infringing files are on Usenet for downloading by others.

Our UK Digital Economy Act passed last year gives rights holders the right to identify downloaders of infringing material by forcing ISPs to provide their name and address found from the IP number they are allocated. But the DEA does not provide any legal basis for rights owners to pursue the "pirates" that host files for downloading.
See this report from the BBC.

No one knows!

A survey in 2007-8 showed 62% of UK users are unaware of the existence of Cleanfeed and the IWF. 61% don't trust BT and 65% don't trust the IWF because the system implements "silent censorship" - that is you don't know about sites which are blocked and cannot therefore complain about it. Most users would prefer an "open censorship" model where a help message is shown when users try to access a blocked site, and 57% want an "unblock" request form.

So there we are, drifting into censorship of the internet, with little public debate or knowledge. We have to have a bigger discussion about this. A separate report just issued by the OSCE (find it here) clearly found that existing approaches to web control (like the "three strikes and you are off" law are against many agreed human rights agreements which fundamentally say that open internet access is a human right.

EU debt - worth repeating

Here's two images culled from the web. with my comments underneath.



Debt to GDP is a fair measure of the situation and clearly there are some EU countries with problems of overspending. Italy looks almost as bad as Greece, and worse than Portugal or Ireland! But we have to consider who owns the debt, as far as I know a fair amount of Italian debt is owned by the Italian banks. Whereas the Greek debt is widely owned by other country's banks, notably Germany and France.

Never the less the EU rules are that countries should keep within 60% and many of them clearly don't. There's a lot of sorting out to do.



And here are the debtors compared to their 2010 GDP numbers. Italy and Greece are the only ones well over 100%. But Greece is very much smaller than the others, ranking 8th in the list. Everyone worries about Spain but they are really not so bad. They have high unemployment but that should be curable. Germany is disappointing as the largest economy, it is both over the EU limit and not doing very much to help others balance their account. It's probably haircut time!

Audio measurements

I have been trying to work out how to measure the performance of my audio system, in terms of dynamics and frequency response. First a bit about the audio performance of digital systems.

Digital audio levels

A digital audio recording cannot go above the level when all the bits in a sample are '1's. The Mac OS X defines 0dB as all the bits at '1'. The normal CD 0dB is is defined as OS X -12dB, and HD 0dB is defined as OS X -18dB, thus giving CDs an overhead of 12dB and HD audio an overhead of 18dB before digital clipping.

CD are recorded at 16bits/44.1kHz sample rate, HD is normally at 24bits/96kHz.

The CD's 16bits give an overall range of 96dB from silence to clipping, and HD gives 144dB. So referred to their respective 0dB levels CDs have 96-12 = 84dB range for normal recordings, and HD has 144-18 = 126dB.

The CD is a rather poor when trying to record live music as its range of 84dB plus an overhead for peaks of only 12dB does not match the range of sounds produced by, for example, an orchestra which can range from silence to +130-140dB. HD is a lot better with a range of 122dB and 18dB for peaks.

Music bandwidth

If you think about it the breath sounds of a person playing a flute are rather like a steady wind, in other words a very low frequency! The lowest notes from an organ are down to 16Hz, you tend to feel these sounds rather than hear them, but you do sense them and it is important to record and playback these very low frequencies. So at the bottom end I believe sound equipment should go down to at least 2Hz, with as much DC coupling as possible to prevent rapid roll off of the response.

At the top end many argue that since the human ear can only hear at very best up to 20kHz, with most of us capable of 12-18kHz depending on age, we need only handle up to 20kHz in our audio recordings and playback.

But this is a wrong argument, if we want to playback the sound made by a violin, then we have to reproduce all the frequencies and harmonics that the violin makes. And these stretch up to 40kHz or so. A trumpet's harmonics stretch up to 80kHz.

With the 44.1kHz sampling rate of a CD you are, at best limited to recording 22kHz, but at the recording stage you must filter out steeply any frequencies above this. In practice this means filters starting at 19-20kHz. Failure to cut off higher harmonics will cause severe distortion on decoding the digital audio. HD is a lot better using 96kHz, thus able to handle frequencies up to 48kHz.

Why do we need to handle these harmonics, you cannot get the true timbre of a sound unless you record the full frequency range it makes including all its harmonics. A cymbal crash has 40% of its audio power above 20kHz, a rattle of a bunch of keys has sounds up to above 50kHz. An audience applauding has a huge range of high harmonics, and poor, limited systems will easily show there limitations.

Testing

An Apple Mac has an internal audio core that operates at 32bit, and up to 192kHz at least. Thus giving it a huge dynamic range before clipping and a wide bandwidth. So a Mac can be used for audio measurements.

Source and measurement

A freeware program called Signal Inspector has an adequate Tone Generator, with the range we need (say 5Hz to 50kHz) and it has a reasonably accurate level calibration, you can set the output to be CD -12dB or HD -18dB as your reference level. For measurement of the system output the program Sound Studio, which also records up to 96kHz sample rate and 24bits, can be used.

An audio file can be recorded with frequencies over the whole range, and saved in AIFF format (uncompressed PCM) at 24bit/96kHz. This file can then be played back using Sound Studio, Quicktime or iTunes and the system output monitored using Signal Inspector or again Sound Studio. If Sound Studio is used then the system output can be recorded and studied later.



The top program running is Sound Studio with its recording window and its input monitor window shown, the bottom two windows are two tone generators, for left and right, using Signal Inspector.

The performance of the DAC and ADC in the Mac is impressive and analog signals can be generated and monitored. Digital signals can be connected by an optical TOSLINK/SPDIF input/output connection for checking the performance of items like the Apple Express and Apple TV.

Patching

If you want to feed audio from the output of one program to the input of another then the excellent utility Sound Flower can be used, if this is combined with the input/output control provided by the PTHVolume program, you will have a very flexible set up.

Noise spectrum

As a matter of interest Signal Inspector can generate a Noise signal, when this is recorded via Sound Flower to Sound Studio, and the Audio Fourier Specrum analysis made, this is the result:

Thank God, Goodbye, Murdoch

What the News of the World front page should have read is

Thank God

Goodbye

This newspaper and some others a bit like it are a scourge on our society, far from the holier than you view they have of themselves - we expose wrong doing,, blah, blah, blah... they deceive people into very damaging beliefs and attitude to life. They act as life substitutes, people read these rags and adopt their opinions, as a alternative to thinking for themselves.

I would class soaps in the same way. People watch them and lead the characters lives, not their own. They feel the characters emotions and hold the characters opinions.

We need to clean up

Time for our society to clean this up. It is probably not something that can be legislated away, but our politicians can certainly speak out. Cant' they? So let's be clear, we want a better news reporting, not scandal peddling press. We want less editorial opinion making, less cosying up to politicians, and more plain, good news. Like the Times used to be, or like the New York Times, Le Monde, Figaro or Corriere della sera and many other newspapers are.

HiFi nirvana

The staring point for HiFi nirvana is Apple's media solution. This stores your music on either a computer or on an iPod/iPad or iPhone.

AAC lossy and FLAC lossless

One thing that is important is to realise that the Apple iPod, iPad and iPhone rely on Apple's choice of AAC lossy compressed music files, recorded at 16bit/44.1kHz (CD standard), but compressed, and because these are lossy they are not as good as CD's for quality. So if you make up your music media centre using just an iPod, iPad or iPhone then you are limited to music purchased from iTunes Store in the AAC format. If you include a computer in the setup you have a much better chance to have HiFi reproduction, as iTunes running on a computer can store AAC lossy music files, CD AIFF ripped music files (plain uncompressed files) or HD audio download FLAC files at 24bit/96kHz. You will have to convert these to Apple's lossless format using a program like XLD but this is simple.

It goes without saying that a Mac computer is better in all respects than a Windows PC...

Media centre to loudspeaker

Now how to get the music from your iTunes/iPod library, running on the iDevice or on your computer?

I should explain, there are two types of amplifier, a plain analog one or an amplifier with a digital audio input and a DAC (Digital Analog Converter). If you have an analog only amplifier then you have two choices, connect the amplifier from the iDevice or computer with a cable, or use an Airport Express WiFi interface. If you have an amplifier with a DAC, either built-in or separate, then you have the choice of connecting by an Optical link (TOSLINK, SPDIF) to your computer, or over WiFi with an Airport Express or the new Apple TV 2.

I suggest the Apple TV2. For two basic reasons, it can also feed your TV with video over an HDMI output and it can handle audio up to 16bit/48kHz - which is a simple down-sample from even HD audio at 24bit/96kHz, thus preserving the audio quality.

So my choice is the Apple TV 2. Now comes the choice of DAC and power amplifiers. First the amplifiers. One of the issues about audio is that the bandwidth must be preserved to equal as much as possible the actual sounds made by the instruments. Many instruments make sounds well above the human hearing top threshold of 20kHz (actually I doubt if anyone can hear 20kHz, most likely the limit is 12-18kHz depending on your age). But to get the timbre and dynamics of the instruments right you do need a wider audio bandwidth. A good target is 40-50kHz to end, and at least 5Hz bottom end to get the breathiness of voices and the bumph from low notes.

So how to build such an amplifier? First the power supply, a toroidal transformer (cuts down stray magnetic fields and adds efficiency, rectifiers and good size condensers. I use these from HK (eBay) and a UK electronics distributor:





And then the amplifiers proper. Here a very good choice is the superb modules from Hypex. These are Class D and thus have low dissipation, they are available in various sizes from 180W to 700W! I chose the UcD180 version





Now what about a DAC? There are a millions DACs on the market some ridiculously expensive. There are a much more limited number of DAC chips from which most of them are made. There is also a lot of misunderstanding about DACS (more expensive = better syndrome). Frankly I am of the opinion that a good DAC can be cheap. I mean even the best chipsets in the world (Wolfson WM...) are less than £5, so why would a DAC cost £500? I chose to source from HK and I found one made by Muse using the TDA1543 chips, in fact the design uses 4 of them and sounds very good. Cost? About £40 only.



I built the whole lot into a fancy box and put a volume control in there and a pretty blue LED to show when its active. Total cost for power supply, amplifiers plus DAC around £200.

Now the interconnect

My choice is the Apple TV 2 so that I can stream both video and audio over WiFi. I can leave my computer in my study and have the media wirelessly sent to the living room. I can remotely control iTunes on the my computer using Apple's Remote App on my iPad or iPhone.



And the results are wonderful, I use a pair of Spendor loudspeakers which are small enough to please the wife, but have a sound big enough for me. HiFi nirvana.

Apple's Time Capsule, media centre

I think Apple is missing a great opportunity with the Time Capsule. This product is a combination of a broadband router (needs external ADSL modem) and a WiFi NAS storage.

Now if it was able to run an OS like iOS then it could do a lot more things. Two of which would be very attractive to customers

1 iTunes. Image if you had iTunes running on your NAS. You would not need a computer, you could just use your iPod, iPad or iPhone to control it with the Remote App, and stream the audio and movies to Apple TV (HDMI video and digital audio out) or to an Airport Express (analog or digital audio out).



You would need a new App to do purchasing through the iTunes Store, but this should be pretty simple to write.

Such a setup would attract thousands of people who are searching for a home media centre solution.

2 A web server! Which could interface with the iweb application (now sadly being retired?) and allow you to create your own web hosted site. The only drawback here is that you would need a fixed IP address and a registered Domain name, but these are easily overcome hurdles of the internet.

So how about it Apple? Especially number 1.

Light Peak on USB

What a mess! I am heartily fed up with Apple's ever changing strategy for high speed interfaces, for displays and external drives. Firewire, USB 2.0, DisplayPort... and now Thunderbolt.

But what is very interesting is that Sony have got it right. They have integrated Intel's Light Peak technology into a USB connector. Now that is sensible and clever. They support the standard USB interface (3.0 no less) AND Light Peak in the same universal plug and socket.

A slight problem is that the controlling body for USB standards does not permit this integration. But they will undoubtedly come round when it turns out to be a popular move. They should have a long discussion and agreement with Intel and straighten things out.

So

Sony RIGHT

Apple WRONG