Hi, my name is Steve Ball and I'm a Principal Program Manager Lead on the Windows Sound Team. I'd like to take a moment and give some background on sound schemes in Windows as well as the new sound schemes released as Ultimate Extras and their relationship with the default Windows Vista scheme.

Default Windows Vista Sound Scheme
The default Windows Vista sound scheme was designed with the same principles that were used in designing the Windows Vista visual elements and desktop experience.  In contrast, the Windows XP sounds, while appropriate at the time and for that product design, were very ‘Western' and literal, using pianos and western orchestral instruments.   The XP sounds were designed to complement the ‘photo-realistic' Bliss desktop (blue sky, green grass photo.)  The Windows XP sounds can also be rather percussive and jarring in the context of day to day PC use, so it was an explicit goal to re-orchestrate the default Windows Vista sounds to complement the softer, cleaner theme and user interface elements in Windows Vista.  

For Windows Vista, it was an intentional design goal to avoid ‘reinventing' the User Interface language for sound.  For example, the "new mail" sound in Windows XP and in Windows Vista consist of the same pitches, interval, and timing. 

New Mail (Notify)

The Windows Vista ‘new mail' sound has simply been re-orchestrated to match the softer, more -rounded Windows Vista Startup Sound whose ‘sonic palette' was derived from the gentle and flowing Robert Fripp Soundscapes sessions that were recorded at Microsoft Studios in 2005 and 2006.   

Session 1: http://channel9.msdn.com/Showpost.aspx?postid=151853

Session 2: http://channel9.msdn.com/showpost.aspx?postid=287615

Fan Fact: The shutdown sounds for both of the new UE Sound Schemes are pulled directly from these Fripp sessions.  There are in fact two shutdown sounds included with each of these UE schemes - for each scheme, there is also longer shutdown sound in the %windir%/media/%scheme_name% folder that is actually too long to use as a Windows Vista shutdown sound -- but we included it anyway so Fripp fans could get a greater sense of context about where this shorter sound came from - or map it manually to a different sound event if they wish.

Here is some additional background about each of the new schemes:   

Ultimate Extras Glass Sound Scheme
The "Ultimate Extras Glass" sound scheme utilizes the same design language and principles as the default Windows Vista sound scheme, however, this set has an additional glassy ‘edge' that can be heard as a more percussive envelope applied to each of the sounds.   From one point of view, the sounds in this set feel like they are made with ‘glass' instruments.   The sounds in this set have a sort of clinking glass root with a polished or ‘frosted' haze effect applied to their outer surface - this is intended to be directly analogous to the transparent ‘glassy' window effects that are built-in to the Windows Vista chrome.

Ultimate Extras Pearl Sound Scheme
The Pearl sound scheme further extends the intentionally-subtle design attributes of both the Windows Vista default sound scheme and the Ultimate Extras Glass scheme, with less focus on reverberant, sometimes clinking  ‘glassy' sounds in exchange for a richer, milky, more percussive sonic palate.   The Pearl sounds are harder and less reflective and reverberant, more like the rich and rounded surface of a pearl in contrast to the fragile resonance of a wine glass.   More concretely, the Pearl sounds are cleaner, clearer, and brighter than the ‘Glass' sound scheme. 

Both of the new Ultimate Extras sound schemes embody more percussive elements in contrast to the soft edges of default Windows Vista sound scheme and they extend of the existing sound design language established by XP and Windows Vista.  Functionally, the percussive elements of these sound schemes may also help users hear Windows events from a greater distance, if that is desired.   They are intended to provide an extended personalization option for users who wish to differentiate their Windows Vista experience from the default experience.    

Occasionally, people stop me in coffee shops and cafes and ask:  did the Robert Fripp sounds make it into Windows Vista?  There is a long answer and a short answer.  Here is the short: the Windows Vista Startup Sound is the primary "Fripp" appearance in Windows Vista, although many of the new inbox sounds were orchestrated based upon the sound and feel of the hours of Fripp Soundscapes we recorded at our Windows Vista sessions.

For some additional background on the Windows Vista sounds, click here to check out our Windows Vista Sounds Q&A.

If there is interest, I can go deeper in future posts about any of these areas.

- Steve

The following is an article from another of my colleagues on the Windows Vista Sound team, Kristin Carr.  Kristin is a Program Manager and works with Steve Ball, who previously has shared his insights into how Windows Vista handles sound.  If you have questions for Kristin, please leave a comment below.

Many people have a general idea of what S/PDIF is -- perhaps by seeing it as a label on an audio output, or on a feature list for a product.  But what is it exactly, and how do you use it?  This post will cover some of those details.

On a PC, the audio is stored and processed digitally until the final output stage when it is usually converted to an analog signal that directly feeds your speakers.  However, there may be times when you want to transmit the signal digitally to a different device that will be used to play the sound, such as a receiver.  In these cases, you may want to postpone converting the signal to an analog one, and instead transmit the signal digitally to avoid any degradation and additional noise that may occur when transmitting an analog signal.

For this purpose, S/PDIF (Sony/Philips Digital Interconnect Format) was developed.  Often referred to by the name of the connector (including Toslink, RCA, or simply "Optical" or "Digital Out"), S/PDIF specifies a method of transmitting a digital signal so that it can be received and interpreted correctly by the connected device.  You may ask yourself, "How complicated is it to transmit a signal?  Why do we need a special protocol?"  Consider that the digital signal consists of a series of bits, and within that series, the bits are grouped to correspond to a sample of audio, and an even larger subset of those are grouped to correspond to a particular channel.  In order to enable a receiver to properly interpret all of those bits in the correct order, it is necessary to have a format for transmitting those bits.  This is where S/PDIF comes in.

S/PDIF can be used to transmit two channels of digital audio in real time over a single connection.  S/PDIF specifies a particular bit pattern that a receiver can use to latch onto the stream.  Once the receiver has synced up with the stream, S/PDIF specifies the order of the audio bits and how they should be arranged in a stream so that the receiver can properly interpret it.

However, there may be times when you wish to transmit more than two channels of audio over the S/PDIF link.  This is where compressed audio can be used.  Audio compression is a technique used to transmit equivalent information using fewer bits.  This is done through a number of techniques.  Some techniques, referred to as perceptual coding, take advantage of the fact that humans can only hear certain sounds.  These methods of compression usually involve discarding bits that only contribute a minimal amount to what a listener needs to recognize a given sound.  Other methods take advantage of numerical redundancies in the signal in order to effectively transmit the same information in a smaller amount of space.  Dolby Digital and DTS are two common types of compression.  Regardless of the technique, compression enables a digital audio signal to use fewer bits to transmit the audio.

The result of this compression is that it enables you to transmit the content for up to 5.1 channels of audio over S/PDIF in space that would have only fit 2 channels if the audio had been uncompressed.  This is great once the signal has been encoded (synonymous with compressed), but once a signal has been encoded, that same signal must also be decoded after it has been received so that it can be sent to speakers.  This means that your receiver must be capable of decoding the compressed audio signal in order for you to hear the correct sound.  This is the tradeoff necessary to allow you to transmit more than two channels of audio over S/PDIF.

Another direct consequence of transmitting a compressed audio signal instead of an uncompressed audio signal (more commonly known as PCM) is that the volume of that signal cannot be modified once it has been encoded.  Because the bits in an encoded signal no longer directly correspond to the volume of that signal, it is impossible to increase the volume until it is decoded.  This explains why your PC cannot control the volume of your sound when you are using Dolby Digital or DTS as the output.  The connected device will be the only place where the volume can be changed.

To recap, in order to avoid the electrical interference and noise present on an analog connection, consider using S/PDIF to transmit the signal digitally.  If you'd like to transmit more than two channels, consider sending encoded content which allows you up to 5.1 channels over S/PDIF.  You may also want to consider HDMI, but that's a post for another time!

If you have a large collection of MP3s, WMAs and other audio files, you probably have quite a few where the tag information isn’t set up properly. In other words, they don’t come up with the correct track name or artist in your media player.

Editing these tags manually can be a laborious task, but fear not, the contributers at MusicBrainz offer a solution to your problem. As they say themselves:
MusicBrainz is a community music metadatabase that attempts to create a comprehensive music information site. You can use the MusicBrainz data either by browsing this web site, or you can access the data from a client program — for example, a CD player program can use MusicBrainz to identify CDs and provide information about the CD, about the artist or about related information. You can also use the MusicBrainz Tagger to automatically identify and clean up the metadata tags in your digital music collections.

The website has a number of applications that you can download which access the database. The one I found most useful was Picard, which provides an interface to search the database and use the information to rename and tag the audio files with the correct information. I didn’t find Picard particularly intuitive to use; however, the authors have provided some quality documentation to instruct users on how the application works. Here are a few images of the software in action. If anyone struggles with the software after reading the instructions, leave a comment on this post and I will record and post a video of how to use it.

Here is that list of badly tagged mp3 files in Picard.

Using the search facility on Picard opens up a listing of matching information on the MusicBrainz website. I navigated to the appropriate album listing, and pressed the green ‘Tagger’ button.

Picard presented the information in the right pane. I selected the files in the left pane, pressed the ‘Scan’ button, and when the list in the left pane was empty I pressed ‘Save’ to make the changes.

Here is the file listing with the correct tag information in place.

I finally decided that I needed to create and correct the tag information on my audio files after becoming sick and tired of some of them not registering with Audioscrobbler, which is the software used on the music based social-networking site LastFM. The software records all the music you play on your computer, and even some portable audio players, and creates charts from the information. You can see my page here. The site enables you to create fancy widgets to put on your blogs, social networking pages and other websites too, like this one:

So get those audio files tagged and let the World that you are obsessed with prog rock.

Below is part 2 of an audio series by Windows Vista Audio team Program Manager Richard Fricks, the first being Richard’s piece on Using a microphone array to enhance sound capture . This follow-on article details how to get more out of your PC by using Read More……(read more)

Below is part 2 of an audio series by Windows Vista Sound team Program Manager Richard Fricks, the first being Richard’s piece on Using a microphone array to enhance sound capture.  This follow-on article details how to get more out of your PC by using a digital microphone.

The digital microphone is a perfect fit for Windows Vista’s microphone array technology.  Digital microphones have been around for years, but until recently, the ability to integrate such technology into an everyday laptop computer at an affordable price has not.  Did I mention they are incredibly compact?  Here is a picture of a bottom-port Akustica digital microphone:

Akustica AKU2000

This is a great example of a high quality, cost-effective digital microphone that is easily integrated into a laptop PC.

There are some unique characteristics of this particular microphone that warrant mention.  First of all, Akustica has a unique fabrication process that allows them to incorporate the entire design onto a single chip of silicon.  This monolithic design places the sensor, microphone circuitry, amplifier and converter all together on one chip.  This is a great step forward that provides significant advantages over analog microphones as well as other digital microphones that require multiple chips.  One of the easiest advantages to articulate is its superior immunity to RF interference.

For comparison purposes, listen to the following audio clips.  These clips were made using the same laptop equipped with both a traditional electric condenser microphone (ECM) and an Akustica digital microphone.  They provide a clear example of how electrical noise can inject itself into the audio capture stream and how well the Akustica digital microphone is at rejecting this interference.

Wi-Fi Interference

GSM Noise

Any of those noises sound familiar?  After I heard the GSM noise, I found myself thinking “Oh, so that’s what was causing that strange sound on my PC speakers every time my mobile phone rang!”

Another advantage of the digital microphone is the flexibility it provides in placement.  A good place to position a microphone is in the screen’s bezel.  However, this is also a location where there is a lot of RF noise.  With its excellent immunity to such interference, the digital microphone can easily be placed in this area where it is not only less susceptible to keyboard, hard-drive and other physical noises, but also allows for a position that is more directly aligned with the talker’s voice.

Single-chip digital microphones also have low manufacturing tolerances, which makes them more suitable for microphone-array applications where microphone matching is important.

If you are shopping for a computer equipped with a microphone array for use with Windows Vista, you need to keep in mind the various microphone array geometries that are supported.  The array geometry refers to the number, type, and position of the microphones.  The microphone array technology on Windows Vista was carefully tuned to provide the highest level of support for the following two and four microphone array geometries:

Small two-element Array:  This geometry consists of two microphones, 100mm apart.

Big two-element Array:  This geometry consists of two microphones, 200mm apart.

Linear four-element array:  This geometry consists of four microphones with the far right and far left microphone 190 mm apart and the inner two microphones 55mm apart.  A second geometry layout allows for the far right and left microphones to be 160mm apart and the inner two microphones to be 70mm apart.

L-Shaped four-element array:  This geometry consists for four microphones mounted in the shape of the letter ‘L’.  It actually looks like a backwards upside down ‘L’, but that would make for too cumbersome of a name!

This design is targeted for a tablet PC where the screen can be flipped around.  When writing on the table, this screen position can cause the hand to cover its lower right or left corners.  By positioning the microphones in the manner described here, the hand will not interfere with the microphones’ operation.

In general, the more microphones in the array the better, but here is a general rule of thumb:

• If you will be recording in a quiet office and will be sitting no more than 2 feet away from the computer then a microphone array equipped with two microphones should be sufficient.
• If you will be recording in an office or cubicle with normal noise levels and up to 6ft away from the computer then a microphone array equipped with 4 microphones should be sufficient.

In either case, I highly recommend finding a laptop equipped with digital microphones.

For those programmers out there who want to learn how to capture audio processed by Windows Vista’s microphone array technology, I hope to be ready to share my programming experiences with you sometime in November.

If you’d like to dig deeper into the topics I have presented above, you can find some great white papers under the subject “Microphone Arrays” here.

Thanks for reading and happy recording!

- Richard Fricks, Program Manager, Windows Sound Team

The following post comes from my colleague Steve Ball, Senior Program Manager for Sound in Windows Vista, and continues his team’s on-going series on how Windows Vista treats various forms of audio.

—–

Part I: Why does my Windows sound sometimes “glitch?”

Windows is a rich and complex OS designed for multi-tasking users whose tasks must share access to scarce system hardware and resources.  Unfortunately, despite multiple decades of incredible advances in PC and CPU architectures, there are non-trivial, complex interactions between applications, processes, and devices in even the most advanced personal computers that make a supposedly “easy” task — like playing back music without occasional glitches — much more difficult than it may seem at first glance.

Another way of thinking about this:  it seems odd that a modern >$2000 PC may sometimes have trouble seamlessly playing back music when $20 CD players can effortlessly playback music without glitches. 

So why do many $2000 PCs occasionally glitch while playing back music?  The quick answer is this:  Windows is not a single-function device like a CD player.

A slightly longer answer goes like this:  even an average Windows machine today is commonly used simultaneously as a media player, word processor, presentation projector, spreadsheet number cruncher, authoring tool, photo editor, media server, video recorder, music composition tool, communications device, search engine, virus detector, data compressor and decompressor, and backup manager.  And these are only a few of the possible tasks and processes that are run at the same time on the hundreds of millions of Windows machines that are in use today.  Each of these tasks or processes, in isolation, would hardly tax the resources of modern PC hardware.  But in our multi-tasking world, unavoidable resource conflicts do sometimes occur between the huge and diverse ecosystem of Windows hardware that enables these tasks.  Even on the most expensive, brand-new machine, occasional glitches can occur if and when the system attempts to divide its finite resources among these multiple, diverse, independent, power-hungry activities.

What is a glitch?

A glitch is a perceivable error, gap or pop in the sound caused by discontinuities in the audio signal during playback or recording which result from processing or timing problems.  Glitches during music playback can sound like a loud “pop” or like a brief slice of silence randomly inserted where your music should have been.  Some customers have also described what “glitching” in their own words as:

• audio stops a little bit
• breaks up
• choppy
• clicking
• corruption
• crackle/crackling/crackly
• interruption
• jitters
• jumpy
• skipping/skip/skips

For the purpose of this discussion, let’s lump all of these descriptions together under one general class of problems and call these “glitching.”  While a glitch that happens during music playback can be annoying and unsettling, a glitch that occurs while you are recording or communicating with someone can result in frustrating and unacceptable data loss.

What causes my Windows sound and music to glitch?

Digital media processing is time-sensitive.  Playback requires specific work to be performed by a given deadline — otherwise presentation or data loss can occur.  A “glitch” occurs when a deadline for time-sensitive processing is missed or when time-sensitive data is lost.

For example, in Windows Vista, playing back music involves “work” that must be done at least every 10 milliseconds so that there can be a continuous stream of music out to your speakers.  The “simple” task of playing back music consists of the following steps, all of which must be completed before a strict deadline:

1. a small chunk of data from a music file needs to be read from a disc (CD or hard drive)
2. this data needs to be “decompressed” or “decoded” (usually in system memory) so it can be streamed out to your speakers in a format that your sound hardware understands
3. the decompressed sound data needs to be copied from system memory to your sound hardware memory
4. the data in your sound hardware needs to be sent to your speakers at the appropriate time
5. repeat steps 1-4 flawlessly every 10 milliseconds (ms)

In this example, if any of these steps aren’t completed on time, then the user could hear a glitch in the music playback.

Elliot Omiya, Architect on the Sound dev team, puts this 10ms cycle into perspective:  “it’s just slightly longer than the time it takes a nerve impulse to travel from the end of your finger to your brain (~8ms), known as NCV (nerve conduction velocity).  Because synapses are like network switches, there is switching time involved before the nerve impulse gets to the brain, i.e., switching time adds to latency.”

There is some good news in this story:  Windows developers have made significant progress over the years in reducing glitching across key multimedia scenarios.  For example, music playback on an otherwise “lightly loaded” system can be generally as smooth as that $20 CD player.

But because of the multi-tasking nature of Windows and the vast array of new and legacy hardware in the ~1B PCs that are used to playback music today, this allegedly simple process is made more complex by the resource sharing that occurs between applications and hardware.  For example, it is not uncommon for certain older devices driver to occasionally “lock out” the CPU for 10-50ms, thereby causing obvious audio glitches.  This is just one example of the kinds of complex hardware, driver, and OS interactions that can cause glitches.

In summary, some of the common sources of glitches today include:

• CPU starvation
• GPU starvation
• Resource contention from devices and drivers (sometimes called “IO contention”)
• Network devices
• And, of course … bugs in applications, OS, drivers and/or hardware

My colleague on the Windows Sound team, Larry Osterman, also pointed out to me recently that humans are actually “hard-wired” to be disturbed by audio glitches.  In an exchange about this topic, Larry observed that audio glitches are more obvious than video glitches because the ear’s tuned to notice high frequency transients — his visceral example of this idea is an image of a stick snapping in the woods behind you as an audio event that wakes you up before a bear wanders into your path. 

In my second post on this topic, I’ll go a bit deeper in sharing details of work we’ve done in Windows Vista to address some of the known sources of potential sound glitches, including some additional background about a recent discovery of an apparent connection between multimedia playback and network throughput.

I wish to acknowledge the contributions and suggestions from my colleagues Hakon Strande, Richard Fricks, Alex Ferreira, Lan Ye, Larry Osterman and Elliot Omiya for this series of posts.