Dithering?

Posted on August 22, 2003 by Stephen Dawson

Dithering has two meanings. The first is what I’ve been doing lately, although I have submitted my latest Institute of Public Affairs Reviewcolumn, plus a lengthy piece to Australian HI-FI on … dithering. In this latter context dither is noise added to digital audio to reduce other problems. Being a true gentleman, Greg Borrowman, the editor of Australian HI-FI, has not only purchased this article but granted me permission to simultaneously post it here. For your edification. But do buy the magazine when it comes out. Aside from the graphics being more detailed in my piece, and it including my DVD reviews on Adaptation and Being John Malkovich, it will have lots of great stuff not written by me.

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The Dictionary of Home Entertainment is up

Posted on August 17, 2003 by Stephen Dawson

It is incomplete, has a great deal more internal linking to be added and, no doubt, some more terms. Consider it to be a work in progress. Nevertheless, with 122 entries so far, I think there is enough information in the Dictionary of Home Entertainment to guide you through some of the intricacies of the field.

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Subjective vs Objective testing

Posted on August 16, 2003 by Stephen Dawson

Here’s a report of a study that bears somewhat on the problem of assessing the performance of home entertainment equipment. In brief, it seems that statistical models are significantly better at predicting outcomes, diagnosing illness and all sorts of other problems than human experts.

How does this relate to home entertainment equipment? The problem with experts is that they are subject to the same human weaknesses that the rest of us are. They overestimate their success rate. They tend to forget their errors.

There is a strong pressure amongst the audiophile community to be able to hear, for example, the differences between interconnects. It has almost become the definition of an audiophile! That the cables measure in no way different to each other is taken to be a failure of technology to detect something that the human ear can.

But there is an alternative explanation: the ear connects to a brain that is all too human.

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Doing my duty

Posted on August 16, 2003 by Stephen Dawson

I have spent around eleven hours before Quicken CashBook today, keying in trivial sums of money, all to administer my tiny part of the Australian government’s taxation system. That is, I’m working out how much tax I have to pay the government for the privilege of remaining out of jail. I still have at least that much more work to do on it. But I’ll try to add some more entries here. I really will. In particular, I’m planning to build a glossary which, I hope, will be of use to readers.

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Where have I been?

Posted on August 14, 2003 by Stephen Dawson

JVC DLA-SX21 projectorSorry dear reader, I’ve been on a few deadlines. Reviews of various digital set top boxes and the Perreaux SXH1 headphone amp now in.

Last night I was fiddling with JVC’s new DLA-SX21 projector, based on its D-ILA (for Digital Direct Drive Image Light Amplifier) system. This uses reflective LCD panels (actually, Liquid Crystal on Silicon) rather than the more common transmissive types. For some reason this comes with a decidedly odd resolution of 1,400 by 1,050 pixels in 4:3 ratio. First impressions: can’t match DLP for contrast ratio, but it delivers an incredibly smooth picture. The reason is that there are virtually no electronics on the perimeter of the panels’ pixels, so the pixels are displayed with virtually invisible borders. No screen door effect. Very good indeed.

I was also trying to assess whether playing DVDs from a PowerDVD on a computer using a high resolution analogue connection to the projector would produce a better result, resolution wise, than a DVD player. The short answer is yes, but only a slight one. Not to the extent I expected. I shall explore this more.

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It’s about time: the perfect projector for PAL DVDs?

Posted on August 12, 2003 by Stephen Dawson

ScreenPlay 5700 projectorIn September InFocus will release its ScreenPlay 5700 projector in Australia. Could this be the perfect home theatre projector? It uses what is apparently Texas Instrument’s newest DMD, the Matterhorn. I say apparently because TI has seen fit not to mention it on its DLP web site. So much for up to the minute promotions!

I have long maintained that for PAL countries XGA is a very good resolution for projectors. That’s because they offer 1,024 by 768 pixels. If you are playing ananamorphic PAL DVD, then you can work out the vertical resolution of a 4:3 projector this way. Multiply the horizontal resolution by 9 and then divide by 16. Do this to 1,024 and you get 576 pixels vertically. Since PAL delivers a 576 line picture, that makes a perfect match with no rescaling. Potentially this is a much better picture.

The problem with projectors until now is that they have been designed with computer applications in mind. Or, in the case of widescreen models, with either high definition or US-style NTSC resolution in mind. See NTSC is 480 lines. The maths to upscale to the 720 lines available on DLP projectors based on the Mustang chip is easy: multiply by 1.5. But PAL, while it works well, receives a 1.25X increase. I am not sure that this doesn’t actually detract from picture quality.

The problem with XGA has been, despite the mathematical nicety of the system for PAL, it seems like a shame to throw away the 200,000 pixels at the top and bottom of the screen. The Matterhorn apparently offers a native 1,024 by 576 pixel resolution which should be simply perfect for PAL DVD playback (and NTSC viewers will, for once, get the compromised performance of modest upscaling!)

Posted in DVD, Equipment, Video | Leave a comment

Wow, what a find! Free audio analysis software

Posted on August 8, 2003 by Stephen Dawson

RightMark Audio AnalyzerThe poor freelance audio writer simply cannot afford to buy all the test gear he would like. Golly, even something as mundane as 250 watt 8 ohm resistors for testing power outputs cost around $AUS100 each … and this writer has seven of the damned things. I’d love a high-end digital storage oscilliscope, but have to make do with a cheap analogue one (still $AUS1,000). And as for measurements: well, it’s just as well that I’m a dab hand at basic mathematics!

Then, yesterday, I stumbled on some software called RightMark Audio Analyzer, put together by some excellent programmers in Russia. This software seems intended primarily for testing sound cards in computers, but if you have a good sound card then it can be used for testing other stuff as well. It measures frequency response, noise, dynamic range, total harmonic distortion, intermodulation distortion and channel crosstalk. And does it extremely well. It will generate HTML pages with the test results, graphs of all these measurements (the frequency response graph shown here is of an in-out loop of a Terratec DMX 6fire 24/96 sound card). You can even subtract two frequency responses to cancel out the effect of your sound card’s frequency aberrations when you’re measuring external stuff.

How much do reckon this would cost? How about nothing at all!

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Comparing the comparable: High Resolution audio vs the CD

Posted on August 8, 2003 by Stephen Dawson

I’ve just uploaded to my Home Entertainment pages my 1999 comparison of a Chesky recording. Comparing a recording with itself? Why? Well, one is on DVD in high resolution 96kHz, 24 bit PCM, while the other is merely a CD, 44.1kHz, 16 bits. Are they different? Not all that much. This piece was originally published in Australian HI-FI.

Posted in Audio, CD, DVD | Leave a comment

Copying files with DRM

Posted on August 7, 2003 by Stephen Dawson

The always interesting Gene Expression Blog has an interesting discussion on the futility of Digital Rights Management on music files.

Posted in Audio, Copyright | Leave a comment

S/PDIF Misconception

Posted on August 7, 2003 by Stephen Dawson

PowerDVD 5 control panelA couple of nights ago I installed CyberLink’s new PowerDVD 5 Deluxe. Good stuff — with some worthwhile improvements over version 4.0, particularly software DTS decoding (this was previously an optional extra). But I couldn’t work out this ’24/96 LPCM Direct Output’ feature, so I went to its support page and wrote:

In FAQ ID number 1366 it states “(25) 24/96 LPCM Direct Output, supports 24bit/96kHz LPCM audio output with more crisp and clear sound. To enable this feature, users should have a sound card that also supports 24bit/96kHz audio output.” I am using a Terratec DMX6fire 24/96 sound card with the latest drivers, but when playing a 24/96 Chesky DVD (which does not have prohibition on 96kHz output), the signal is downsampled to 48kHz. How do you enable 96kHz S/PDIF output?

Much to my surprise, I got an email this afternoon pointing me to a response, which said:

SPDIF cannot support 96/24 SPDIF output since it is the limitation of SPDIF itself.Please switch to analog output (ie 2-speaker or headphone output interface in PowerDVD) to have 96K output.

But, actually, that’s not quite right. As I responded:

Thanks for the quick response!You wrote: “SPDIF cannot support 96/24 SPDIF output since it is the limitation of SPDIF itself.”

That is correct as far as the original design of S/PDIF was concerned (it was limited to 44.1 or 48kHz and 16 bits), but S/PDIF now defacto supports AC3, DTS and higher LPCM standards. In particular, the Terratec DMX6fire 24/96 *does* ouput 24/96 on the S/PDIF, and it will *accept* 24/96 on its S/PDIF inputs. Furthermore, my Marantz SR18 home theatre receiver (and, indeed, most receivers these days) will accept a 24/96 LPCM signal on its S/PDIF input. Many good DVD players will output 24/96 LPCM S/PDIF (most Sony, Panasonic, Pioneer, Yamaha, Denon, Onkyo DVD players, for example). So it would be nice if PowerDVD would likewise support this output on S/PDIF, instead of downsampling it to 48kHz.

The reason, incidentally, is for those of us who prefer the sound of external equipments’ D/A converters.

UPDATE (Tuesday, 12 August 2003, 12:27 pm): CyberLink replies:

We just delivered your suggestion to our product team. We will take this into consideration for further design. Be free for further suggestions. Thank you.

Posted in Audio, Computer | Leave a comment