I’ve been using Ian’s Secure Knot for over ten years and (I swear I’m not exaggerating) I haven’t had my shoelaces come undone once. As far as I’m concerned, this knot provides military-grade security for your shoes. It looks great, too!

A few years ago, I was disabused of that idea when I did an informal test to compare several well-known music players (iTunes 7, Winamp, Foobar2000, Windows Media Player). The test revealed iTunes 7 to be the outlier producing different output from the rest of the pack.

Today, I will present the results of a more rigorous test using the latest version of iTunes (10.2.1).

Test setup

• Windows 7 Professional SP1 (32-bit) with all the latest updates
• Auzentech X-Meridian 7.1 sound card
• Cool Edit Pro 2.0 audio editing software

Tested players

• Windows Media Player 12.0.7601.17514
• Winamp 5.56
• Foobar2000 1.1.5
• iTunes 10.2.1

MethodolOgy

I played two 10-second MP3 clips in each player, recording the output digitally with Cool Edit Pro 2.0 using the S/PDIF loopback mechanism provided by the sound card driver.

All postprocessing options (crossfade, sound check, etc.) were turned off. Both application and system volume were at 100%.

I used the following MP3 files:

1. a 10-second clip from Wszystko Ch. by Elektryczne Gitary encoded with LAME 3.97 at 256 kbps ABR with high encoding quality (download file)
2. a 10-second clip from Time by Pink Floyd encoded with LAME 3.98 at 256 kbps ABR with high encoding quality (download file)

After recording in Cool Edit Pro (as a 16-bit, 44.1 kHz file which matched the source material), I saved each stream as a text file, which looked like this:

-354	-172
1	203
-447	-443
-2490	-3088
-3504	-3676
-3233	-2944
-3206	-3867
-2829	-4348
-2391	-4461
-2196	-4165...

I also opened each of the two MP3 files directly in Cool Edit Pro 2.0 and then saved it as a text file. This file was used as a reference: the output of each player was compared against it. Cool Edit Pro 2.0 uses a Fraunhofer MP3 decoder (Fraunhofer IIS is the institute where MP3 was developed).

I opened the text files in Notepad++ and synchronized them by discarding the initial silence in each file. The goal was to make sure that the first sample in each file corresponded to the start of the clip to enable direct sample-by-sample comparison.

After synchronization, each text file was opened in Cool Edit Pro 2.0 again. Each waveform was subtracted from the reference waveform to reveal the differences.

Results

Each waveform below shows the difference between the reference output stream (Cool Edit Pro 2.0 with Fraunhofer decoder) and the output stream produced by an MP3 player.

Wszystko Ch. – Windows Media Player 12

Wszystko Ch. – Winamp 5.56

Wszystko Ch. – Foobar2000 1.1.5

Wszystko Ch. – iTunes 10.2.1

As you can see, Windows Media Player, Winamp and Foobar2000 all produced output that matched the reference stream very closely. A review of the text files showed that all three players produced virtually identical bitstreams: the differences between individual samples and the reference stream did not exceed 1, or in rare cases, 2. These differences were not large enough to register on the waveform view, even with magnification.

iTunes 10.2.1, however, added significant distortion that can be seen in the waveform above. In some cases, the samples deviated from the reference values by as much as 5 percent (e.g. 1811 instead of 1719). You can also download the above waveform as a WAV file to hear the “enhancement” added by iTunes. It basically sounds like a very high-pitched sound (> 15000 Hz) of an uneven volume. The ability to hear it will depend on your age: younger listeners will find it more prominent. (Of course, during normal music listening this sound would be very hard to hear.)

The output generated by iTunes 10.2.1 did not depend on the output setting in QuickTime (which iTunes uses to play audio). DirectSound, WaveOut and Windows Audio Sessions all produced the same output.

Time – Windows Media Player 12

Time – Winamp 5.56

Time – Foobar2000 1.1.5

Time – iTunes 10.2.1

Again, Windows Media Player, Winamp and Foobar2000 match the reference stream, while iTunes engages in creative decoding. In this sample, the distortion is smaller: personally, I cannot hear anything when I play the above waveform.

Conclusions

Cool Edit Pro 2.0, Windows Media Player 12, Winamp 5.56 and Foobar2000 1.1.5 all decoded the MP3 clips in virtually the same way. iTunes 10.2.1, on the other hand, produced a distorted output stream. While the distortion is probably inaudible in normal listening situations, it seems to mean that the latest version of iTunes fails to conform to the MP3 standard and is probably best avoided by users who care about audio fidelity.

Notes

In further tests using the same samples, I found that iTunes 9.2.1 matched the reference stream as well as WMP, Winamp and Foobar2000 – it would therefore seem that it decodes MP3 files properly. I also evaluated MediaMonkey 3 and detected very significant distortion (much larger than iTunes 10.2.1), even after disabling as many postprocessing options as I could find (volume leveling, clipping protection, crossfade, smooth stop/seek/pause, remove silence – did I miss anything?).

Check out the thread at Hydrogenaudio for an interesting discussion and independent measurements which confirm my findings.

The volume is not high – the sound is overpowered by the refrigerator in my kitchen, the sound of water flowing in the pipes in the bathroom. I can often hear it over my PC (several very quiet fans + quiet 7200 rpm hard drive) or during a conversation in a quiet room when nobody is talking.

As I’ve spent a lot of time reading and thinking about tinnitus, I want to share some tips that helped me get over the initial shock and go back to living normally. Much of the advice in this FAQ is based on what I’ve read about Tinnitus Retraining Therapy (TRT), the leading clinically proven tinnitus treatment.

What causes tinnitus?

Sometimes tinnitus has an easily identifiable cause, such as earwax buildup, certain drugs, hypertension, temporomandibular joint (TMJ) disorder, or acoustic neuroma. (The Tinnitus FAQ has a catalogue of possible causes.)

Most cases of tinnitus, however, are “unexplained”. That is, they result from changes in the brain that are still poorly understood. Dr James Kaltenbach has written a good scientific introduction (PDF) to the current theories on the causes of tinnitus.

One thing that is known about this type of tinnitus is that it is associated with hearing loss. Between 60 and 90% (depending on the source) of tinnitus patients have some degree of hearing loss. This is, however, not a true explanation of tinnitus because the majority of hearing-impaired people don’t have tinnitus, and a significant percentage of tinnitus patients have normal hearing (especially among younger people).

When will my tinnitus go away?

If your tinnitus is of the unexplained kind, the question is difficult to answer. If you were recently exposed to loud noise (for example, you went to a concert), you may just have temporary tinnitus that will go away in a few days. In many other cases, tinnitus goes away on its own within 2-3 months. In still others, it takes 2-3 years. On the other hand, there are people who have had tinnitus for over 20 years. Unfortunately, I am not aware of any reliable statistics that would show what percentage of cases resolve within a few months. The best I could find was this informal survey.

What can I do about my tinnitus?

You can go to a doctor in case your tinnitus is due to something that can be fixed or treated easily.

You can try one or more remedies recommended by tinnitus patients – vitamin B12, magnesium, ginkgo biloba, caffeine withdrawal and paracetamol – for each of these, you will find people who swear it reduces their tinnitus. And you can certainly avoid wasting your money on the countless “tinnitus cure” scams ran by unscrupulous assholes all over the Web.

Other than that, there is currently no proven method of rewiring your brain to make “unexplained” tinnitus disappear completely and permanently. There are therapies that can lessen tinnitus or even make it disappear (Xanax, notched music therapy), but their effect is temporary, i.e. they must be continued indefinitely if the effect is to be maintained.

However, you can do two very important things:

1. You can stop the noise from bothering you.
2. You can learn not to notice the noise.

If you achieve these two goals, tinnitus will be no more of a problem for you than the color of the walls in your apartment. It will still be noticeable, if you choose to notice it, but it will not be an issue.

Dr Stephen M. Nagler describes this beautifully in his introduction to Tinnitus Retraining Therapy (TRT):

TRT is not a cure for tinnitus.  It is a treatment approach designed with the goal of tinnitus ceasing to be an issue in the patient’s life.  It is designed with the goal of making tinnitus into a pair of pants.  Ninety percent of the time, people are unaware of their pants.  The 10% of the time they are aware, they do not “cope” with their pants, they do not “deal” with their pants, they do not “learn to live” with their pants, and they most certainly do not spend any time worrying whether the following day will be a “good pants day” or a “bad pants day.”  They simply wear their pants; and when the goal of TRT has been met, tinnitus should be just like that!

How do I stop the noise from bothering me?

The first thing you must realize is that the sound itself is not that much of a problem. Unless your tinnitus is uncommonly severe, the noise in your head probably does not interfere with your hearing in a significant way.

The real problem is that (1) you are paying attention to the noise and (2) you are reacting to it in an emotional way. In neurological terms, the auditory stimulus leads to a stress response. You find the sound disturbing, you can’t think about anything else, your heart is racing, you can’t fall asleep at night – all these problems are not due to tinnitus; they are due to your emotional reaction to tinnitus.

Does it have to be this way? No. You are probably surrounded by many sounds that are objectively louder than your tinnitus, yet you don’t give them a second thought. Every day, you sit in front of a computer that has noisy fans and hard drives, but you don’t obsess over it. While driving, you’re exposed to the sound of traffic and your own car, sometimes for hours, but that does not make you miserable. Airline pilots spend half their lives in the noise of jet engines, but they don’t make a big deal out of it. The only difference between tinnitus and those “everyday sounds” is that you interpret those other sounds as “normal background noise”.

As I sit in front of my computer writing this post, I am surrounded by potentially annoying stimuli. I hear the drone of the washing machine that’s running in the bathroom, the whirr of the hard drives in my computer, and some sounds of traffic outside the window. I am wearing eyeglasses that put constant pressure on my nose and ears; worse still, their rims impose themselves on my field of vision, putting a useless blurry border around whatever I’m looking at. To the right of my screen, there is a network router with bright LEDs blinking at irregular intervals. And whenever I move in my chair, it makes a fairly loud squeak. All of these things can be seen as irritating, yet none of them bothers me in the least bit.

There is no objective reason why I should be completely indifferent to all these stimuli, yet be disturbed by tinnitus. After all, tinnitus is just another sound I can’t do anything about.

Your emotional reaction to tinnitus is a matter of attitude. And attitudes to stimuli can change. I remember very clearly that I used to be annoyed by the ticking of the wall clock in my room, to the point that I had to take it down. Guess what? I recently hung it again and now I kind of like it. To take another example, there are people who are annoyed by the noise made by children playing in the playground. Often, the same people will find it much less annoying (or even pleasant) once they have their own children and begin to associate the sound with something pleasant.

Finally, it is helpful to realize that most of your negative attitude to tinnitus comes from the initial shock. If you had been born with tinnitus, would you worry about it? Certainly not. For you, it would be the way the world works – much like the fact that you have to blink every 20 seconds or so. Some people who have had tinnitus since childhood are indifferent to it to the point that they believe it is completely normal.

What is partial masking?

Partial masking is a good technique that can help you stop reacting emotionally to tinnitus. Surround yourself with some sort of noise that blends with the sound of tinnitus without obscuring it completely. Good sources of noise include computer-generated noise, recordings with sounds of nature (rain, ocean, mountain stream, etc.), fans, radio static, air humidifiers, etc. There is a good free online noise generator over at SimplyNoise.com. Remember that if your goal is to reduce your emotional response to tinnitus, the tinnitus should still be partially audible over the masking noise. The reason is that you cannot get used to something you don’t hear. You can then gradually decrease the volume of the masking noise until your tinnitus becomes as boring and unworthy of attention as the buzz of the refrigerator in your kitchen.

Does tinnitus deprive you of silence?

Among tinnitus patients, there is a tendency to think “I will never hear silence again”, but it is worth noting that humans are incapable of hearing complete silence anyway. In a well-known study by Heller and Bergman (1953), out of 100 tinnitus-free university students placed in an anechoic chamber , 93% reported hearing a buzzing, pulsing or whistling sound. (Here’s another, more recent study of the same phenomenon.)

How do I learn not to notice the noise?

At the core of tinnitus is The Loop. The Loop is my own term for the positive feedback loop created by the following two mechanisms:

1. The more attention you give to your tinnitus, the louder it gets. (What happens is, you are telling your brain “This sound is important, I want to hear it more clearly”.)
2. The louder your tinnitus is, the more it attracts your attention, which in turn makes it even louder, and so on.

This is a vicious circle that can be extremely hard to break out of. In the first few days after my tinnitus appeared, I gave it so much of my attention that eventually I could hear it even while watching TV.

The loop starts when you focus your attention on the noise. Once you let yourself do that, the noise will get louder, making it much harder to get your mind off it. So Rule Number One is: don’t start The Loop. Whenever you find your attention wandering towards the noise, use your will to immediately focus on something else. Get busy. Slap yourself on the face. If you’re trying to fall asleep, try counting. Remember how miserable you felt the last time you let yourself focus on the noise. Do whatever it takes to take your mind off the tinnitus. If all else fails, mask it with music or some noise. But whatever you do, don’t start The Loop.

Learning to take your attention away from tinnitus takes training. One technique that helps with this is having a loud ticking clock in your room. The moment your attention wanders towards the tinnitus, focus on the tick-tock instead.

If you haven’t heard your tinnitus for some time, don’t listen for it. Don’t ask yourself: “Do I hear the noise now?” or “Has it really gone away or is it just temporarily masked by ambient noise?”. In the first weeks after I got tinnitus, whenever it stopped being noticeable, I would go to a quiet room and put on my isolating headphones to see if it really went away. I did this many times a day and all it did was make me notice my tinnitus again. In the end, I had to set a rule: I am allowed one “tinnitus test” per day, when I get up in the morning. For the rest of the day, no checking.

Remember: If you listen for tinnitus, you are just training your brain to hear it better. Don’t do it. Focus on other things in your surroundings and your life.

What if I’m already in The Loop?

Ah, yes. When you’re in The Loop, your tinnitus seems so loud that it’s like a tiger in your room – it seems damn near impossible not to pay attention to it. In addition, the stress you are probably experiencing does not make it any easier to exercise mental control.

Still, you have to help yourself. You have to get out of The Loop somehow. Here’s a method that worked for me: Mask the hell out of it and go to sleep. When you wake up the next morning, use every ounce of self-control you have to focus your attention on things other than the tinnitus. Keep telling yourself: if I let myself focus on it, it will just get bigger and even harder to ignore. Whenever your thoughts start wandering toward the tinnitus, slap yourself on the face or pinch the back of your forearm (this serves as negative reinforcement). The goal is to develop a mental habit to distract yourself every time you start thinking about your tinnitus. As time passes, it will get easier and easier to distract yourself when tinnitus becomes noticeable.

It can be hard to keep this up for the whole day, especially in the beginning, so use masking liberally. (Full masking is not recommended in Tinnitus Retraining Therapy because it removes the noise completely rather than letting you get comfortable with it, but my experience is that when you’re going crazy from listening to your tinnitus, masking it partially doesn’t make you any calmer. There are times when you need emergency measures.)

When you cannot help but pay attention to your tinnitus and it’s beginning to stress you out, you can try the following mental technique that I’ve found very effective. I call it the Refrigerator Trick. The trick is to imagine that the sound of tinnitus is made by an actual device in the room, perhaps a small refrigerator. It’s amazing that simply having that thought brings about instant stress relief. As soon as the sound is associated with an everyday object, it seems the brain no longer has any reason for alarm. Once the tinnitus is classified as an “everyday noise”, it is much easier to take your mind off it. To make this visualization more convincing, you can picture what the refrigerator looks like, where it’s standing, etc.

Useful resources on tinnitus

• Dr. Nagler’s Tinnitus Site – a very well-written site with tinnitus information and support, by Dr Stephen Nagler, who is a tinnitus patient himself
• Tinnitus Retraining Therapy (TRT) “uses a combination of low level, broad-band noise and counseling to achieve the habituation of tinnitus, that is the patient is no longer aware of their tinnitus, except when they focus their attention on it, and even then tinnitus is not annoying or bothersome”. The author of TRT, Dr Pawel Jastreboff also wrote a book about it.
• Tinnitus Support Message Board – the largest and best forum for tinnitus patients
• Tinnitus FAQ
• SimplyNoise.com – a free online noise generator

Update (Sep 2011)

I still have tinnitus, but have become indifferent to it to a degree I would never have thought possible. Basically, now it’s like the sound of the hard drive in my laptop. Sure, I notice it sometimes, but I don’t focus on it; I just go back to whatever I was doing. I’m certainly not sitting there writing an e-mail on my laptop and thinking “OMG, here’s the damn hard drive noise again, why won’t it stop?”. Needless to say, I don’t check the intensity of my tinnitus every day anymore. In fact, I’ve gone weeks without noticing it.

I used to be scared of going to sleep without masking sounds, as the silence at night brings the tinnitus out. Now it’s no big deal: I don’t pay attention to it, and on the rare occasion that I do, it doesn’t bother me; it’s just “that familiar sound” to me.

Slightly puzzled, I opened up my case, unplugged all the fans and hard drives and started plugging them in, one by one, to isolate the culprit. No luck. Although I could hear the whine now and then, I could not place it.

It was clear that the problem lay somewhere else. I shut down my computer and all the other electronic devices in my room and started listening. The whine was there, clear as day, only now it appeared to be coming from the part of my room where the radiator was. I put my ear to the radiator, but the noise didn’t get any louder. I took a walk around my apartment – I could hear the damn thing in every room! What could it be?

I was out of ideas. My only remaining suspects were the ventilation system in the supermarket next door and the electrical transformers in the basement five floors below me. The problem was that the noise seemed about equally loud in every room, while you’d expect it to get louder as you get closer to the source.

It wasn’t until the next day that a simple experiment with a pair of earplugs and isolating headphones finally revealed the truth: there was a constant noise in my head. I had freaking tinnitus. The next few days were hell for me. Obsessed with the incessant whine I could not get away from, I became a nervous wreck unable to perform even the simplest everyday tasks.

Today, a month later, the sound in my head has not gone away, though it bothers me much less. In my next post, I will share some tips that helped me get over the initial shock and go back to living normally.

When I launched the Task Manager, the cause of the problem became obvious. The CPU was under load: both cores were fully utilized by ORTHOS, a simple program used to stress-test CPUs and RAM. In fact, ORTHOS had been running for 58 hours. I had started it two days ago to heat up my room in the night, and forgotten to shut it down the next morning. (My Radeon HD4850 is a much better heater, but I wanted to effect a gentle increase in temperature, not turn my room into a sauna.)

Chew on this: Over the past two days, I had been using my machine almost continuously and hadn’t realized I had two computationally intensive processes sucking the life out of both CPU cores! (In the interest of full disclosure, there was a brief moment yesterday evening when I thought that skipping forward and backward in a HD video clip took a bit too long, but I put it down to normal differences between video formats.) If I hadn’t checked my CPU parameters this morning, which I did for a completely random reason, who knows how much longer it would have taken me to realize something was amiss.

Now, that wasn’t the first time that I’d had ORTHOS running in the background while using my computer. Those other times, it was a different experience altogether. Applications took a long time to launch, websites took much too long to load – the lack of responsiveness was simply unacceptable. I would have sworn to you that ORTHOS was crippling my PC.

Of course, the only difference between those other times and the last two days was in my head. Back then, I knew I had ORTHOS stressing my CPU, so I expected poor performance, which is why every single operation seemed slow to me. Without that knowledge and that expectation, my PC was, it seems, perfectly responsive.

Today’s experience will make me think long and hard before I decide to spend money on a new CPU. And every time I hear someone say how much snappier their new Intel i7 rig feels next to a Core 2, I will wonder: would they even notice if I secretly swapped out their i7 for their old Core 2?

Math Input Panel

I’ll start with the Math Input Panel. This is a feature so awesome that you want to show it to your friends. You scribble a mathematical expression with your mouse, touch screen or graphics tablet, and it is magically converted into proper typographical form.

But then you want to insert your formula into a document. You open the built-in (and greatly improved) Write editor of Windows 7. You click “Insert”. Nothing happens. You open Paint (also improved in Windows 7) and try again. Nothing. OpenOffice Writer? Nothing. Word 2003? Nada. Does this thing even work?

Then you read the small print. The Math Input Panel only works with applications that support MathML. As of this writing, the only popular application with MathML support would be Word 2007. There are no other output options. The Math Input Panel cannot generate code in LaTeX, which is the de facto standard in the mathematical community and has been adopted by projects such as Wikipedia, WordPress and jsMath. It cannot generate OLE objects for older versions of Word. It does not even let you paste the damn equation as an image. How can something so ingenious be so useless?

Windows Firewall

On its face, the Windows Firewall has everything you need to say goodbye to third-party firewalls like Comodo. It’s lean, well-integrated with the OS, and the new “Windows Firewall with Advanced Security” console lets you specify detailed rules for inbound and outbound connections to/from specific programs and ports:

Perfect, isn’t it? Unfortunately, it has two fatal shortcomings:

• Any application can add its own exceptions to it by means of a simple API call. Why? The official rationale is that it is not the firewall’s job to block malicious applications from accessing the network – once you have executed malicious code on your computer, it can pretty much do whatever it wants, including sending data via a trusted process in a way that is invisible to the firewall. There is some truth to this, but a less permissive firewall would still make things that much harder for wrongdoers. More importantly, however, this reasoning misses the use case where you want to prevent legitimate applications from “phoning home”. If I block Adobe Photoshop from using my Internet connection, it probably won’t go so far as to hijack another process, but it will make use of an official Windows API to add an outbound rule for itself.
• There is no way to get pop-up notifications about outbound connections. In a typical software firewall, when a new application attempts to establish an outbound connection, you get a pop-up window which enables you to allow or block the connection, and add a permanent rule for this application. The Windows Firewall does not have this functionality. The only thing you can enable is a notification about blocked incoming connections, which gives you a chance to unblock an application. What about outbound connections? The best you can do is block all unknown applications, but then you will never know that an application wanted to access the Net. It will just silently fail.

Sticky Notes

The Sticky Notes feature looks really useful at first. For someone who stares at his screen for most of the day, the Windows desktop seems to be a logical place for “notes to self”. The UI is pretty straightforward and has some nice touches, such as the fact that every note has a little plus button that lets you quickly add another note.

Unfortunately, for some unknown reason Sticky Notes is not a gadget, like the weather thingy you can see on the screenshot above. It’s a separate application. One that cannot be minimized to the system tray. And I don’t know about you, but I don’t like tiny utilities like this taking up space on my taskbar. I need the space so I can comfortably switch between my productivity applications.

Windows Backup

The final “almost perfect” Windows 7 feature I’m going to talk about is Windows Backup. Now this is a seriously exciting utility that promises to replace third-party backup applications like Acronis True Image. On the face of it, it has everything you need. Scheduled and on-demand backups? Check. System drive snapshots? Check. Backups of selected folders? Check. Incremental backups? Check. Restore from bootable CD/DVD? Check. Time needed to back up 500 GB of data to an external USB hard drive? 35 hours. That’s right. Thirty-five freaking hours. (If you suspect there is something wrong with my setup, read these other reports.) Try it once and you’ll never try it again.

It’s as if Microsoft developed a perfectly good backup application and then decided to cripple it on purpose, just to let ISVs make a buck. I don’t want to give my money to Acronis again, especially after reading their official response to a compression bug in TrueImage Home 11 (“just turn off compression”), but it seems I’m going to have to.

Now for the rest of you. As you can probably figure out from the title, I’m going to try to convince you to use English versions of your software. Now, I am the webmaster of a site which tells you how to learn English, so you might expect I would tell you how daily exposure to English menu items, system messages, help files, and all the other textual UI elements will program your brain with correct English. (Which, by the way, would all be true.)

But today I’m not going to write about the importance of getting English input every chance you get. Instead, I will give you a very practical reason to install English versions of your operating system and other software rather than versions localized in your native language.

Suppose you have just updated the drivers for your nVidia card. Unfortunately, something has gone wrong and every time you reboot your machine you see the following error message:

Sterownik ekranu przestał działać, ale odzyskał sprawność.

(The error message is in Polish because, in this example, we will assume you are Polish and use the Polish version of Windows.) “Motyla noga”, you curse to yourself while opening your Web browser. If there’s one thing you’ve learned online, it’s that the Internet has the answer to your computer question. Other people must have had the same problem and there must be a forum post somewhere which has the solution.

But what are you going to type into Google? What keywords would be likely to occur in this forum post you want to find? In all likelihood, the poster would have quoted the error message itself.

Except they would have quoted it in English, not Polish. Let’s face it — it is much more probable that the solution to your problem is posted on one of the many English-language tech forums than on one of the few Polish-language ones. A Google Groups search on “nVidia” turns up 17,000,000 group threads in English and only 211,000 in Polish (1/80 of the English figure).

So now you’re stuck with your Polish error message, trying to figure out the exact words the English version might have used. “The screen driver has failed?” “Malfunctioned?” “Stopped working?”

Of course, I have an English-language version of Windows, so if I am having computer issues, I can simply read the English error message off the screen (in our example it’s “The display driver has stopped responding and has successfully recovered”), type that magic phrase into Google together with the name of the malfunctioning device or application and boom! — within minutes I’m reading about the secret registry setting that makes it all okay.

Now that I think about it, having an English-language version of Windows probably accounts for something like 30% of my troubleshooting ability. Moreover, using English-language software is useful not only when troubleshooting — I find it equally helpful when I just want to learn how to do something in Windows, Office, Photoshop or even a Web app like GMail. I can just search on the names I see instead of wondering what is the English name for warstwy dopasowania (adjustment layers). And I can apply the solution more easily because I don’t have to translate all the names back into Polish.

It would perhaps behoove me to give you “the other side” of the argument, but the matter seems pretty clear-cut to me: If you want to get help with your software (and who doesn’t?), it helps to use the same version that most of the potential helpers use. And with this, I leave you.

Volume Shadow Copy is a service that creates and maintains snapshots (“shadow copies”) of disk volumes in Windows 7 and Vista. It is the back-end of the System Restore feature, which enables you to restore your system files to a previous state in case of a system failure (e.g. after a failed driver or software installation).

Does volume shadow copy protect only my system files?

No. Volume Shadow Copy maintains snapshots of entire volumes. By default, it is turned on for your system volume (C:) and protects all the data on that volume, including all the system files, program files, user settings, documents, etc.

How is this different from what’s in Windows XP?

In Windows XP, System Restore does not use the Volume Shadow Copy service. Instead, it uses a much simpler mechanism: the moment a program attempts to overwrite a system file, Windows XP makes a copy of it and saves it in a separate folder. In Windows XP, System Restore does not affect your documents – it only protects files with certain extensions (such as DLL or EXE), the registry, and a few other things (details). It specifically excludes all files in the user profile and the My Documents folder (regardless of file extension).

When are the shadow copies created?

Volume shadow copies (restore points) are created before the installation of device drivers, system components (e.g. DirectX), Windows updates, and some applications.

In addition, Windows automatically creates restore points at hard-to-predict intervals. The first thing to understand here is that the System Restore task on Vista and 7 will only execute if your computer is idle for at least 10 minutes and is running on AC power. Since the definition of “idle” is “0% CPU usage and 0% disk input for 90% of the last 15 minutes, plus no keyboard/mouse activity” (source), it could take days for your machine to be idle, especially if you have a lot of programs running in the background.

As you see, the frequency with which automatic restore points are created is hard to estimate, but if you use your machine every day on AC power and nothing prevents it from entering an idle state, you can expect automatic restore points to be created every 1-2 days on Windows Vista and every 7-8 days on Windows 7. Of course, the actual frequency will be higher if you count in the restore points created manually by you and those created before software installations.

Here’s a more precise description: By default, the System Restore task is scheduled to run every time you start your computer and every day at midnight, as long as your computer is idle and on AC power. The task will wait for the right conditions for up to 23 hours. These rules are specified in Scheduled Tasks and can be changed by the user. If the task is executed successfully, Windows will create a restore point, but only if enough time has passed since the last restore point (automatic or not) was created. On Windows Vista the minimum interval is 24 hours; on Windows 7 it is 7 days. As far as I know, this interval cannot be changed.

What cool things can I do with Volume Shadow Copy?

• If your system malfunctions after installing a new video card driver or firewall software, you can launch System Restore and roll back to a working system state from before the installation. If you can’t get your system to boot, you can also do this from the Windows Setup DVD. This process is reversible, i.e. your current state will be automatically saved as a restore point, to which you can later go back. (Note: System Restore will not roll back your documents and settings, just the system files.)
• If you accidentally delete 10 pages of your dissertation, you can right-click the document, choose Restore previous versions, and access a previous version of it. You can open it (in read-only mode) or copy it to a new location.
• If you accidentally delete a file or folder, you can right-click the containing folder, choose Restore previous versions, and open the folder as it appeared at the time a shadow copy was made (see screenshot below). All the files and folders that you deleted will be there!

Note: While the Volume Shadow Copy service and System Restore are included in all versions of Windows Vista, the Previous versions user interface is only available in Vista Business, Enterprise and Ultimate. On other Vista versions, the previous versions of your files are still there; you just cannot access them easily. The Previous versions UI is available in all versions of Windows 7.

Is Volume Shadow Copy a replacement for versioning?

No. A versioning system lets you access all versions of a document; every time you save a document, a new version is created. Volume Shadow Copy only allows you to go back to the moment when a restore point was made, which could be several days ago. So if you do screw up your dissertation, you might have to roll back to a very old version.

Is Volume Shadow Copy a replacement for backups?

No, for the following reasons:

• Shadow copies are not true snapshots. When you create a restore point, you’re not making a new copy of the drive in question — you’re just telling Windows: start tracking the changes to this drive; if something changes, back up the original version so I can go back to it. Unchanged data will not be backed up. If the data on your drive gets changed (corrupted) for some low-level reason like a hardware error, VSC will not know that these changes happened and will not back up your data. (see below for a more detailed description of how VSC works)
• The shadow copies are stored on the same volume as the original data, so when that volume dies, you lose everything.
• With the default settings, there is no guarantee that shadow copies will be created regularly. In particular, Windows 7 will only create an automatic restore point if the most recent restore point is more than 7 days old. On Windows Vista, the minimum interval is 24 hours, but remember that the System Restore task will only run if your computer is on AC power and idle for at least 10 minutes, so it could take days before the conditions are right, especially if you run a lot of background processes or do not use your computer frequently.
• There is no guarantee that a suitable shadow copy will be there when you need it. Windows deletes old shadow copies without a warning as soon as it runs out of shadow storage. With a lot of disk activity, it may even run out of space for a single shadow copy. In that case, you will wind up with no shadow copies at all; and again, there will be no message to warn you about it.

How much disk space do Volume Shadow Copies take up?

By default, the maximum amount of storage available for shadow copies is 5% (on Windows 7) or 15% (on Vista), though only some of this space may be actually allocated at a given moment.

You can change the maximum amount of space available for shadow copies in Control Panel | System | System protection | Configure.

How efficient is Volume Shadow Copy?

It’s quite efficient. The 5% of disk space that it gets by default is usually enough to store several snapshots of the disk in question. How is this possible?

The first thing to understand is that volume shadow copies are not true snapshots. When a restore point is created, Volume Shadow Copy does not create a full image of the volume. If it did, it would be impossible to store several shadow copies of a volume using only 5% of that volume’s capacity.

Here’s what really happens when a restore point is created: VSC starts tracking the changes made to all the blocks on the volume. Whenever anyone writes data to a block, VSC makes a copy of that block and saves it on a hidden volume. So blocks are “backed up” only when they are about to get overwritten. The benefit of this approach is that no backup space is wasted on blocks that haven’t changed at all since the last restore point was created.

Notice that VSC operates on the block level, that is below the file system level. It sees the disk as a long series of blocks. (Still, it has some awareness of files, as you can tell it to exclude certain files and folders.)

The second important fact is that shadow copies are incremental. Suppose it’s Wednesday and your system has two shadow copies, created on Monday and Tuesday. Now, when you overwrite a block, a backup copy of the block is saved in the Tuesday shadow copy, but not in the Monday shadow copy. The Monday copy only contains the differences between Monday and Tuesday. More recent changes are only tracked in the Tuesday copy.

In other words, if we were to roll back an entire volume to Monday, we would take the volume as it is now, “undo” the changes made since Tuesday (using the blocks saved in the Tuesday shadow copy), and finally “undo” the changes made between Monday and Tuesday. So the oldest shadow copy is dependent on all the more recent shadow copies.

When I delete a 700 MB file, does VSC add 700 MB of data to the shadow copy?

No. When you delete a file, all that Windows does is remove the corresponding entry (file name, path, properties) from the Master File Table. The blocks (units of disk space) that contained the file’s contents are marked as unused, but they are not actually deleted. So all the data that was in the file is still there in the same blocks, until the blocks get overwritten (e.g. when you copy another file to the same volume).

Therefore, if you delete a 700 MB movie file, Volume Shadow Copy does not have to back up 700 MB of data. Because it operates on the block level, it does not have to back up anything, as the blocks occupied by the file are unchanged! The only thing it has to back up is the blocks occupied by the Master File Table, which has changed.

If you then start copying other files to the same disk, some of the blocks formerly occupied by the 700 MB file will get overwritten. VSC will make backups of these blocks as they get overwritten.

What are the security implications of Volume Shadow Copy?

Suppose you decide to protect one of your documents from prying eyes. First, you create an encrypted copy using an encryption application. Then, you “wipe” (or “secure-delete”) the original document, which consists of overwriting it several times and deleting it. (This is necessary, because if you just deleted the document without overwriting it, all the data that was in the file would physically remain on the disk until it got overwritten by other data. See question above for an explanation of how file deletion works.)

Ordinarily, this would render the original, unencrypted document irretrievable. However, if the original file was stored on a volume protected by the Volume Shadow Copy service and it was there when a restore point was created, the original file will be retrievable using Previous versions. All you need to do is right-click the containing folder, click Restore previous versions, open a snapshot, and, lo and behold, you’ll see the original file that you tried so hard to delete!

The reason wiping the file doesn’t help, of course, is that before the file’s blocks get overwritten, VSC will save them to the shadow copy. It doesn’t matter how many times you overwrite the file, the shadow copy will still be there, safely stored on a hidden volume.

Is there a way to securely delete a file on a volume protected by VSC?

No. Shadow copies are read-only, so there is no way to delete a file from all the shadow copies.

A partial solution is to delete all the shadow copies (by choosing Control Panel | System | System protection | Configure | Delete) before you wipe the file. This prevents VSC from making a copy of the file right before you overwrite it. However, it is quite possible that one of the shadow copies you just deleted already contained a copy of the file (for example, because it had recently been modified). Since deleting the shadow copies does not wipe the disk space that was occupied by them, the contents of the shadowed file will still be there on the disk.

So, if you really wanted to be secure, you would also have to wipe the blocks that used to contain the shadow copies. This would be very hard to do, as there is no direct access to that area of the disk.

Some other solutions to consider:

• You could make sure you never save any sensitive data on a volume that’s protected by VSC. Of course, you would need a separate VSC-free volume for such data.
• You could disable VSC altogether. (After disabling VSC, you may want to wipe the free space on your drive to overwrite the blocks previously occupied by VSC, which could contain shadow copies of your sensitive data.) However, if you disable VSC, you also lose System Restore functionality.  Curiously, Windows offers no option to enable VSC only for system files. If you want to protect your system, you also have to enable Previous versions (see screenshot to the right).
• The most secure approach is to use an encrypted system volume. That way, no matter what temporary files, shadow copies, etc. Windows creates, it will all be encrypted.

Notice that VSC only VSC only lets you recover files that existed when a restore point was created. So if the sequence of events is as follows:

create file → create restore point → make encrypted copy → overwrite original file

the original file will be recoverable. But if the sequence is:

create restore point → create file → make encrypted copy → overwrite original file

you are safe. If you make sure to encrypt and wipe files as soon as you create them, so that no restore point gets created after they are saved on disk in unencrypted form, there will be no way to recover them with VSC. However, it is not easy to control when Windows creates a restore point; for example, it can do it at any time, just because your computer happens to be idle.

Can I prevent VSC from keeping snapshots of certain files and folders?

Yes, but you have to edit the registry to do that. Here are detailed instructions from MSDN.

What happens when VSC runs out of space?

Most of the time, most of the data on your disk stays unchanged. However, suppose you uninstall a 5 GB game and then install another 5 GB game in its place. This means that 5 GB worth of blocks got overwritten and had to be backed up by VSC.

In such “high-churn” scenarios, VSC can run out of space pretty quickly. What happens then? VSC deletes as many previous shadow copies as necessary, starting from the oldest, until it has enough space for the latest copy. In the rare event that there isn’t enough space even for the one most recent copy, all the shadow copies will be deleted. There are no partial copies.

Thanks to Adi Oltean, who was one of the engineers of Volume Shadow Copy at Microsoft, for answering my questions on the subject.

Cahey lit a cigarette and reflected on the van’s relatively conspicuous location. Sloppy surveillance work or a deliberate attempt to scare him into silence? There was no way to know. He was, however, sure of one thing: if they came here, they would find nothing. Knowing that digital content was much easier to protect from prying eyes than papers, photographs and recordings, he had disposed of every physical record of his investigation, leaving only a digitized copy on the hard drive of his laptop computer. Two days ago, he had encrypted all this data using an open-source application called TrueCrypt, making sure to overwrite the original files several times before deletion. Now his data was unrecoverable without the password, and there was nothing anybody could do about it, not even the NSA with their army of PhD’s and their supercomputers. The spooks would be in for a surprise.

“Drrrrrt” — the sound of the doorbell pierced the smoke-infused air. Cahey glanced through the window. The van was gone. As he walked towards the door, he contemplated logging out of his Windows account, but decided against it. Bypassing that layer of security would be a trivial exercise, and it wouldn’t do the government much good anyway, given the fact that everything of interest was now encrypted. He opened the door. On his porch stood five serious-looking men in suits. “Stephen Cahey? We have a warrant to search the premises.”

———-

Agent Jack Trallis looked at the machine he had been ordered to process. It was a pretty standard Dell laptop with a dual-core CPU and a 15-inch screen that was covered with fingerprints. “God, do I hate those glossy displays”, he muttered to himself. He was alone in the room; the other agents were in the living room questioning the suspect. Trallis noticed the prominent TrueCrypt icon on the machine’s desktop. “Uh oh. Strong encryption.” He fixed his eyes on the taskbar at the bottom of the screen. There was a row of oversized, unlabeled icons that reminded him of the Hackintosh he had once built for his girlfriend. The guy’s laptop was running Windows 7. There was still a chance.

He located the Documents folder, opened its Properties window, and clicked on the “Previous Versions” tab. Just as he thought, there were five previous versions of the folder – “shadow copies” created regularly by the operating system as part of the System Restore mechanism. As these snapshots were prepared silently in the background and stored on a hidden disk volume, few users were aware of them. Agent Trallis was smiling. The good guys from Redmond were going to make his job easy again.

He selected one of the snapshots and clicked Open. An Explorer window popped up, showing the contents of the Documents folder exactly as it had appeared three days ago. “This is too funny”, he thought. There was a subfolder labeled Project Foxhunt full of scanned documents and audio files. Trallis grabbed his radio. “Sir”, he called out to his commanding officer, “I’ve got something you might want to have a look at.”

• The new audio stack automatically upconverts all streams to a 32-bit floating-point sample depth (the same that is used in professional studios) and mixes them with the same precision. Because of the amount of headroom that comes with using 32-bit floats, there is no more clipping when playing two samples at the same time. There is also no loss of resolution when you lower the volume of a stream (see below).
• The Vista/Win7 audio engine automatically feeds your sound card with the highest-quality output stream that it can handle, which is usually 24 bits per sample. Perhaps you’re wondering why you should care, given that most music uses only 16 bits per sample. Suppose you’re playing a 16-bit song with a digital volume control set to 10%. This corresponds to dividing each sample by 10. Now let’s assume the song contains the following two adjacent samples: 41 and 48. In an ideal world, after the volume control we would get 4.1 and 4.8. However, if the output stream has a 16-bit depth just like the input stream, then both output samples will have to be truncated to 4. There is now no difference between the two samples, which means we have lost some resolution. But if we can have an output stream with 24 bits per sample, for each 16-bit level we get 2⁸ = 256 additional (“fractional”) levels, so we can still preserve the difference between the two attenuated samples. In fact, we can have ≈4.1016 and ≈4.8008, which is within 0.04% of the “ideal” samples of 4.1 and 4.8.
• Don’t you hate it when you change the volume in your movie player or instant messaging software and instead of changing its own volume, it changes your system volume? Or have you ever used an application with its own poorly implemented volume control (iTunes, I’m pointing at you!)? Well, these abominations should now be behind us. In Vista and Win7, each application gets its own audio stream (or streams) and a separate high-quality volume control, so there should no longer be any reason for application vendors to mess with the system volume or roll their own and botch the job.

So Windows Vista and Windows 7 upconvert all your samples to 32-bit floats and mix them with 32-bit precision into an output stream that, by default, has the highest bit depth that your hardware can handle. The output bit depth is customizable; you can change it in the properties of your audio device. If you change it e.g. to 16 bits, the audio engine will still use 32-bit floats for internal processing — it will just downconvert the resulting stream to 16 bits before sending it to your device.

Now, what about the sample rate? You can set the output sample rate in the audio device properties window, but is there also some internal sample rate that the Windows audio engine uses regardless of your setting? For example, does it upsample your 44.1 kHz songs to 96 or 128 kHz? Unlike the upconverting from 16-bit integers to 32-bit floats (which should be completely lossless), this could potentially introduce some distortion as going from 44.1 kHz to 96 or 128 kHz requires at least some interpolation.

I couldn’t find the answer to this question anywhere, so I wrote to Larry Osterman, who developed the Vista and Win7 audio stacks at Microsoft. His answer was that the sample rate that the engine uses is the one that the user specifies in the Properties window. The default sample rate is chosen by the audio driver (44.1 kHz on most devices). So if your music has a sample rate of 44.1 kHz, you can choose that setting and no sample rate conversion will take place. (Of course, any 48 kHz and higher samples will then be downsampled to 44.1 kHz.)

There is some interesting technical information on the Windows Vista audio stack in this Channel9 video.