Support

Pure Music must be identified as a "trusted" application to launch it, if it was downloaded after installing Mountain Lion (OS X 10.8).

1. Navigate to the Pure Music application icon (should be located in the Applications folder, if installed as advised).

2. Hold down the Control (not command) key on the keyboard and simultaneously click on the Pure Music application icon.

3. Select Open from the pop-up contextual menu that appears.

4. Click Open in the ensuing dialog box, shown below.

If running the software from the mounted disk image on the desktop, instead of copying the Pure Music application to your applications folder from the disk image, disk images will "disappear" when the computer is restarted. The disk image file itself is still on your computer, but the virtual disk image "volume" on your desktop is unmounted.

Locate the downloaded software (depending on your browser settings, likely saved in the Downloads or Documents folders). Double click the Pure Music x.xx file (x.xx being the version number, and may have a .dmg extension) to mount the disk image on your desktop. Then, copy the application (also suggest copying the User Guide) to your Applications folder. (Afterwards, the disk image can be unmounted by selecting its icon on the desktop and pressing command-e, for Eject.)

If you can't find the downloaded software (or Pure Music User Guide) on your computer, you may download it again from our website, and follow the above procedure. You will not have to re-enter your activation code.

http://www.channld.com/download.html

Click here to download 2-minute screencast movie as zip file (2.3 MB)

If the behavior of Pure Music on your system apparently changes, then it's very likely that something else has changed on your system, or changes have been made to the settings in Pure Music.

As far as reloading or reinstalling the Pure Music application or audio device drivers, it is extremely, extremely, *extremely* unlikely that the application file or other software could become damaged (the only case would be if it were deliberately modified, or if there were problems with the hard drive, in which case other computer problems would be apparent), and so reinstalling isn't a very useful thing to do. Deleting the Preferences file (as explained below) sometimes can be useful, however.

For users more accustomed to Windows systems: Pure Music doesn't rely on installing any dynamic linked libraries or other system extensions. The entire functioning application is contained in the application file. To uninstall, just drag the application to the Trash.

The default settings can be reset by pressing the Defaults... button in the Preferences window. A copy of the previous preferences file also will be saved in the Preferences folder.

Alternatively, delete (you must Quit Pure Music first) the Pure Music Preferences file in your home directory, in Library/Preferences/:

Users/username/Library/Preferences/com.channld.PureMusic.plist

The Preferences folder containing Pure Music's Preferences file can be opened by following these steps:
1. In the Finder, select Go To Folder... from the Go menu.
2. Type ~/Library/Preferences as shown in the image below.
(The tilde ~ key is to the left of the numeral 1 key.)



3. Click Go.
4. Locate the file com.channld.PureMusic (or com.channld.PureMusic.plist).
5. Drag the file to the Trash.
6. Launch Pure Music. You will have to re-enter your activation code (copied below for your convenience) and set up the application preferences again, including choosing the sound device.

The Preferences folder also can be revealed by holding down the Option (not Command) key on the keyboard when pressing the Defaults... button in Pure Music's Preferences window.

Deleting the Preferences file would be an unusual last resort in attempting to diagnose or correct a problem. After doing this, you'll have to re-enter the activation code (if you have purchased an activation code), but the code can be copied and pasted easily from your confirmation of purchase email. (Using the Defaults... button as described above will preserve the Activation Code).

The User's Guide is included with the software download, on the disk image (see image below). It's best to copy it to the Applications folder for later reference.

If you don't have the software download any more, it can be downloaded again from our website.

Note: the zip file (one of the standard, Apple-approved means of software distribution on the Mac platform) expands to the disk image file (.dmg). Double clicking this mounts the disk image on your desktop.

If you have your web browser (Safari) set to automatically expand and open downloads, it will be mounted automatically after downloading.

For Pure Music to work properly, the names of any disk drives holding your music must be unique. Your music collection can span multiple disk drives, but the drives must have different names, and also must not have the same name as any other hard drive or disk volume connected to or mounted on the computer.

If you already have more than one drive with the same name, rename the drive that's not used to store music, or iTunes may be unable to locate the tracks on a (newly renamed) music drive.

Example 1

if you have a hard drive called MusicDrive, and you add another hard drive to your computer to store more music, name it something different, such as MusicDrive2.

Example 2

Features are incorporated into Pure Music that are designed to improve performance and give the best possible sound quality. Using the computer optical drive as a "CD player" or transport is not advisable for best sound quality, for a variety of reasons, so this is not directly supported by Pure Music.

However, there is a work-around, which is to use Pure Music's Playthrough feature. This disconnects Pure Music from iTunes so that iTunes playback such as Internet radio is routed through Pure Music. This would include CDs played from the optical media in iTunes.

1. Install the Playthrough feature using the instructions in the User's Guide (or shown during installation of the Playthrough driver). This setup need only be performed once.

To play a CD (or Internet radio, etc.):

2. Select Playthrough in the Pure Music Music Server menu.

3. Insert CD, then play in iTunes.

Airport / AirTunes / AirPlay / iTunes streaming (to an Airport Express or Apple TV) is a proprietary, closed design (prior to OS X 10.8.2) with specifications controlled by Apple. The application programming interface for AirTunes is not publicly available.

Regarding other types of streaming servers, Pure Music also isn't designed to work in conjunction with a (for example) Squeezebox, Sonos, etc., per se. These represent different approaches to playing and managing digital audio, so it is essentially an either-or situation. Pure Music is primarily designed to function to convey audio to audio interfaces / DACs connected directly to the computer.

Of course, your music can be located on a network server, and used with Pure Music. The difference is that it's the music which is connected via a network, not the audio hardware.

If you want to stream high-resolution audio, Pure Music's NetSend feature combined with a remote Macintosh and audio interface will receive up to 384 kHz / 24 bit uncompressed audio, over a low-latency, wired Ethernet connection. This also can be used for streaming upsampled CD format audio (upsampling moves the phase shift resulting from the DAC reconstruction filter to above the audio frequency band, one reason for improved playback quality).

For users who want to be able to use AirTunes to stream to an Airport or an Apple TV or some other networked audio devices, many users have reported success with third party streaming utility software called Airfoil, that intercepts the audio stream from Pure Music. If using Airfoil, be sure to set the Airfoil volume controls to a neutral (0 dB, no boost or cut) position. This way, the benefits ot Pure Music's dithered volume control are preserved, and the audio plug-in support of Pure Music also can be used, as well as managing FLAC playback using the iTunes user interface.

To use AirTunes natively within iTunes disconnect from Pure Music by activating the Pure Music Less is More Controller Mode (described in the Pure Music User's Guide included with the Pure Music download).

If you are running OS X 10.8.2 or later, an AirPlay output device is now available. This device can be selected in the Audio Setup window in Pure Music, to stream to an AirPlay device. Note that (as above) AirPlay is limited to 16 bit, 44.1 kHz (this is an AirPlay limitation, not a limitation of Pure Music).

Ayre: The Ayre must be set to USB Class 2, using the switch on the back of the DAC (set to Rsrv B). See image below from the QB-9 Manual. Note: as of the time of this writing, this is not the factory setting, and must be changed to Rsrv B. Other Ayre DAC models may have a slightly different switch configuration.

Zodiac +: Likewise, the Zodiac must be set to USB Class 2 (UH2), using the procedure described in the Zodiac user manual.

- The computer must be running OS 10.6.4 or later!

- Use Apple's System Profiler (Apple menu -> About This Mac; More Info...) to determine if the DAC is plugged into a shared USB port (the Bluetooth and IR receiver are connected internally via USB). If so, plug the DAC into a different non-shared USB port (this may not be possible on some models of Mac computers).

Prior to OS X 10.7 ("Lion"), Apple provided a special API (Application Programming Interface) feature that allowed sending audio directly to the audio device / DAC in the native format of the DAC.

This mode, called "nonmixable integer stream" mode, slightly reduces computing overhead. It is applicable to sending the audio without any alteration (meaning, precision volume control or audio plug-ins are not possible without conversion to floating point), so its use is confined to a limited number of situations. If volume control, plug-ins or upsampling are used, there is no point to using nonmixable integer stream mode, if the putative benefit comes from avoiding the added overhead of format conversions; precision volume control and other signal processing operations are always performed in floating point format.

Apple removed the ability to send audio in nonmixable integer stream mode in OS X 10.7. However, with the release of the latest Macintosh models with the Core i5 and Core i7 processors, the performance improvement of the combination of OS X 10.7 and these new processors overwhelms the slight disadvantage of not having nonmixable integer stream mode.

In Lion, there is an alternative method, sometimes referred to as "direct mode," which also can be used for accessing native device format streams. We have been investigating this, and it is interesting.

However, using direct mode is extremely risky, because one must write directly to the OS kernel without benefiting from any of the usual API safeguards and memory address protection "firewalls." This is akin to performing open heart surgery on the OS - while the "heart" is still beating!

For a computer that is 100 percent dedicated to audio, this shouldn't "usually" present a problem. However, if the user is browsing the Internet or downloading email or hasn't made the suggested settings to the System Preferences (for instance, disabling Sleep and automatic Apple checking for updates) while playing audio with direct mode, there is a chance of interrupting real-time communication with the kernel / device and causing a kernel panic.

This is the worst possible kind of crash. If this happens at just the wrong time it can trash the hard drive (directory corruption), requiring a reinstall of the OS and complete recovery (all data on the hard drive lost). Or, even worse can trash individual files, which might only be discovered some time down the road, with lurking problems including unpredictable computer behavior (unexplained crashes or freezes), in addition to data loss; and these problems can accumulate and increase in severity.

Journaled volumes are not immune to damage from a kernel panic (startup volume verified after computer crashed from kernel panic, and computer subsequently behaved unpredictably)

One of the fantastic advantages of Mac OS X over all previous Mac OS versions is the use of protected memory. Prior versions of the Mac OS did not employ protected memory, and applications had free rein to modify the contents of memory, including parts used by the OS. In those days, system crashes were commonplace, because a memory addressing bug in an application could potentially overwrite a critical segment of the OS in memory. Accordingly, hard drive crashes were much more commonplace, as well. This situation completely changed with the release of Mac OS X, in which an application only has access to its own memory "sandbox", a significant advance in system reliability. Except that an application with the ability to write directly the kernel, as is done with "direct mode," in a way is a regression to those old days of non-protected memory and its problems.

(Any signal processing operations such as volume control, plug-ins, crossover, etc. must be performed in floating point format for the best sound quality / lowest distortion. If the goal of using an integer stream is to eliminate conversions between integer and floating point format, any putative benefit to using an integer format is eliminated: why perform the extra work to convert back to integer when one already is in floating point?)

It isn't enough to tell users, "just use the computer for audio and don't browse the web, etc. when using direct mode." People often ignore instructions; besides, having a dedicated computer for audio doesn't guarantee that the risk of kernel panics is eliminated. So in keeping with a philosophy of low-risk programming practices, doing things "by the book" and making things as bug-free as possible (a philosophy we have suscribed to for over 16 years), we are not incorporating "direct mode" support at this time. Computer audio should be fun, not frustrating. Any putative benefit pales in the face of having unhappy users with trashed systems. That is not something that is good for the long-term, for anybody concerned. :-)

If using the Memory Play feature, Pure Music benefits by starting with a "clean slate." If you've been working with other applications on the computer, and in particular, any other audio applications / players (except for iTunes), a fresh computer restart can be beneficial. Wait a minute or so for the computer to get into a quiet state (total CPU activity below a few percent), as indicated with Apple's Activity Monitor application, set to monitor All Processes.

Please be sure your iTunes and other system software are up to date. After updating iTunes, it is recommended that you use Apple's Disk Utility application to Repair Disk Permissions (not the same as Repair Disk) on the startup disk.

Incorrect Setting

Correct Setting

Be sure you have your computer set up according to guidelines for audio playback, listed in the Pure Music User's Guide, and on our website (see the heading for Computer tweaking).

In particular, please confirm the following:

• Disable Computer sleep (set to Never, not just set it to a long value) - System Preferences: Energy Saver
• Disable the screensaver (set to Never) - System Preferences: Desktop & Screen Saver
• Disable automatic checking for system updates - System Preferences: Software Update
• If using a laptop computer, operate with the power adapter connected

When the computer attempts to conserve energy or enter sleep mode, this can cause an interruption in communication with the audio device, pauses in playback, or other issues. With the above settings, this will be avoided.

iTunes or any other player that accesses the disk periodically during track playback won't be affected, because the computer will appear to be "busy" to the operating system (OS). Pure Music with Memory Play loading a track into RAM before playing the track will make the computer appear to be idle to the OS, so the above settings are necessary.

The Skip buttons in iTunes will be temporarily disabled if a new playlist is manually selected while a track is playing in Pure Music:

Skip Buttons Enabled (left). Skip Buttons Disabled (right).

Important: In this case, Pure Music cannot automatically segue to the next track, if the Use Skip Button for Track Sequencing option (Music Server preferences) is enabled.

Note: this behavior results because iTunes isn’t actively playing the track: Pure Music is playing the track. An alternative design would be to use iTunes “Ghost Play,” with iTunes actually playing the track in parallel (with the volume at minimum), which would be wasteful and undesirable when the goal is achieving the best playback quality and lowest computer activity level.

If you want to both manually navigate playlists and Pure Music to automatically segue tracks (other than by selecting it and pressing Return on the keyboard), then press the Queue Selection button on the control bar (when finished browsing playlists) and then select (click once) the next track you want to have played. The selected track will be played after the current track, and the Skip buttons re-enabled when the queued track begins playing.

The Queue Selection feature also may be used at any time to set the next track to be played. The track is determined at the time the previous track is finished, not when the Queue Selection button is actually pressed.

A few additional tips:
1. Third party “enhancement” software is available that modifies the behavior of iTunes. These applications / scripts, etc. can in some cases cause iTunes to behave unpredictably. Please first try uninstalling such software if you find playback stalling between tracks.

2. If your music library or playlists contain media types besides audio tracks, disable the Use Skip Button for Track Sequencing option in the Pure Music Preferences.

Note regarding playlists and track sequencing
If you explore or select a different playlist after starting to play a track, the server’s ability to maintain the track sequence may be impaired. The rule is that after changing playlists, when the currently playing track finishes playing, the next track to play will be the track following whatever is the selected track (with the Use Skip Button for Track Sequencing option unchecked).

If you select original playlist without doing anything else, playback of tracks will continue in the original sequence. However, if you select a different track (including from a different playlist), play will continue with the track following the selected track.

Use the Advanced Audio Setup... feature of Pure Music to direct Pure Music to use your DAC for output:

1. Select your DAC / audio interface in the Output pop-up menu in Advanced Audio Setup.

2. Set the sample rate pop-up menu to the maximum available value. (Don't change the Limit Rate pop-up menu default of 384 kHz.)

3. Press the Click To Apply Settings button to lock in the changes you have made.

Receiving reports of clicks and other noises has become extremely rare following the release of Pure Music 1.65a and 1.74a. Accordingly, if this problem manifests only at certain sample rates, this suggests an issue with the playback hardware that is sample rate dependent.

As just one example, the HRT Music Streamer II or II+, on certain models of Mac computers, will exhibit obvious audio dropouts several seconds to a few minutes after switching sample rate to 88.2 kHz, and may even stop playing altogether until reset by disconnecting it. (Note: HRT now has a solution for this issue involving a firmware change.)

A simple test using iTunes playing by itself to try to assess if an issue is dependent on the music player software, such as in the above example, may indicate no apparent playback problems. However, testing with iTunes is not necessarily just a matter of launching iTunes and playing audio.

This requires some care in setup, because iTunes always resamples audio to match the hardware sample rate. If the hardware is set to 44.1 kHz, iTunes will not change the sample rate; it will resample high resolution audio tracks back to 44.1 kHz. If the problem is related to the sample rate of the audio hardware, and since iTunes resamples, there is no way to get iTunes to exhibit the problem, unless the hardware is first set to the "problem" sample rate.

To use iTunes to confirm sample rate dependent or other hardware issues:

1. Quit iTunes (important!)

2. Open Apple's Audio MIDI Setup application (AMS for short; in the Utilities folder inside the Applications folder). Depending on whether you are using the built-in optical or a USB or FireWire connected DAC for output (note the location of the small "loudspeaker" icon next to the device in the attached example image), select it, and then set the pop-up Format menu to the "trouble" sample rate.

If the "loudspeaker" isn't assigned to the output device you want to use, then use the pop-up "gear" menu at the bottom left of the window (this is with AMS in Mac OS X 10.6; in Mac OS X 10.5 the procedure is somewhat different) to assign it to the correct device. Then set the sample rate with the Format menu.

3. Launch iTunes.

4. Play a track (any sample rate). If necessary, adjust the volume in iTunes, up to maximum. Hardware issues will become apparent at this time.

The next step, at this point, is to check the digital connections between the computer and the audio hardware. Try swapping the connecting cable, whether optical, USB or FireWire. Power down the computer, disconnect the audio hardware (both of these steps are important), then power down the audio hardware if it isn't bus powered; then re-connect it and power up the computer again. If attempts to solve the problem are unsuccessful, contact the manufacturer of the audio hardware product and explain that you are having trouble using their product for playback in iTunes. If our experience with such things is indicative, the manufacturer will be forced to focus on the hardware issue once you have confirmed the problem with iTunes.

This happens because of a drift or difference in the sample rate of the internal computer clock (used for the Playthrough driver), and / or your DAC.

The solution requires creating an aggregate device.

1. If you are using Hog mode in Pure Music, you will have to turn it off for your DAC. Click the Click to Apply Changes button. Then, Quit Pure Music.

2. Open Audio MIDI Setup (AMS).

Set the Channel D PAD to the same sample rate as your DAC by selecting the DAC, noting the DAC sample rate, and then use the Format menu to change the sample rate of the Channel D PAD.

3. You will need to create an Aggregate device (use the (+) button at the bottom of the window), configured exactly as shown. (Note: MPS-3 is the DAC used in this example; you will select your primary output DAC.)

Pay careful attention to the Clock source and ordering of the selected ("Use") devices within the Aggregate list.

The play button in iTunes doesn't indicate the play state because iTunes isn't playing the file, of course. This is the point of the software: so that iTunes doesn't play the file. If iTunes were playing the file, the button would change to the (||) state (and, in fact, that's a clear indication that iTunes is playing the file). However, with Pure Music interfaced with iTunes, Pure Music is playing the file, which is why the iTunes button indicates (>). There are other ways the Pure Music user interface indicates playing status (for example, the meter bar says, "Player paused...").

On the other hand, if the iTunes "play" button does change to "pause" (||), this is caused by an interruption between the Pure Music and iTunes handshaking communications. To clear this condition, press the RESET button.

Pure Music cannot affect the system state, so rebooting should never be necessary after running only Pure Music and iTunes, even if the communication between Pure Music and iTunes fails. Also, it isn’t necessary to relaunch iTunes after running Pure Music, or to quit iTunes before launching Pure Music. When Pure Music isn’t running, iTunes will behave in its usual stand-alone fashion. (If iTunes is silent after quitting Pure Music, a simple nudge of the iTunes volume control will restore iTunes’ output volume.)

This is a side effect of activating the "Update Play Position In Remote App" option.

If you aren't using the Apple Remote App on an iPad, iPhone or iPod Touch, this option should not be used.

With the default option "Allow Manual Playlist Navigation" the updates are suspended when iTunes is in the front (selected).

The reason for this design is because Pure Music only updates the play position in the Remote App every 2 seconds or so, to avoid generating excessive RF traffic and transmissions to the Remote. When iTunes is playing the file (another well-known audio player application causes iTunes to play the file, with the iTunes volume muted; the file actually is being played twice, something called Ghost Play) there is a constant stream of RF traffic back and forth to the Remote App, which may have a negative impact on the sound quality. To avoid this, Pure Music only updates the play position occasionally. The downside are cosmetic side effects: the album art may flash and the play button rapidly toggles every 2 seconds. But we feel this is a reasonable trade-off for improved sound quality, which is the reason for using an audiophile-quality music player.

• Tracks purchased from the iTunes store that contain DRM (digital rights management) copy protection cannot be played and will be skipped over. This is beyond our control, because circumventing this protection is illegal under United States copyright law.

Such tracks are encoded as lossy, low quality 128 kbps AAC. If possible, these tracks should be upgraded to iTunes Plus (unprotected) tracks. An alternative work-around is to burn the affected tracks to a CD-R or CD-RW and re-import as AIFF or Apple Lossless. Re-importing in this way removes the DRM copy protection.

• Disabled tracks (the check box to the left of the track name in list view is unchecked) are automatically skipped, the same as in iTunes.

To allow manually playing a single disabled track, check the Allow Manual Play of Unchecked Tracks in iTunes (Special tab of the Pure Music preferences).

• If the media / hard drive holding the track is not available or the track cannot be located (indicated by an exclamation point icon to the left of the track name in list view), it will be skipped, the same as in iTunes.

• Repair Disk Permissions (not the same as Repair Disk) using Apple's Disk Utility application
• Observe guidelines for computer settings (see Skipping / playback interruptions / player stops topic, above)
• Quit iTunes and remove the iTunes plug-in installed by the Amarra Demo application installer (move to the desktop or Trash). It is located here: ~/Library/iTunes/iTunes Plug-ins/

1. Collapse the iTunes window (green button in window).

2. Next, hide iTunes (select Hide iTunes from the iTunes menu).

1. Select Hide Music Server Controls from the Music Server menu in Pure Music.

2. Collapse the iTunes window (green button in window).

3. Hide iTunes (select Hide iTunes from the iTunes menu).

4. Select Hide Pure Music from the Pure Music menu.

Solution: Disable Full Screen Mode in iTunes (View menu).

Configure the Settings... in iTunes DJ to display at least 5 recently played and 5 upcoming songs.

If playing gapless files from a playlist, and the iTunes playback mode is set to loop, initiating play in the middle of the playlist will cause the playlist to loop, continuing with loading tracks at the top of the playlist until memory has been filled.

Therefore, if you then restart play at the top of the playlist, the tracks will not be reloaded, because they've already been considered as part of the group of gapless tracks (even though playback was initiated "below" the current location).

Keep in mind that if the gapless playback mode seems not to work the way you expect, take a moment to consider the way that you have iTunes configured, and chances are that you will find that the music server is functioning correctly.

If the hard drive containing the music has gone into sleep mode and spun down, it will need several seconds to spin up again. Pure Music (and iTunes) will be unresponsive until the disk has "awakened." This includes briefly not being able to access menus or move the window. The "beachball" cursor may appear at such times.

A NAS drive or RAID array can take as long as 30 seconds to spin up. There is nothing Pure Music can do to accelerate this process, so please be patient before concluding that Pure Music has hung. If this is a recurring issue, configure the NAS / hard drive so that it doesn't spin down, using the utility software that is supplied with the NAS drive, or Energy Saver Preferences on the computer.

This cannot occur in iTunes by itself, because iTunes is always accessing the hard disk during playback. With Pure Music Memory Play, iTunes is not accessing the disk. However, if iTunes is in a Pause state for an extended period, you will find exactly the same behavior in iTunes (an apparent "hang") if the hard disk has spun down.

System sleep should be disabled when playing audio (Energy Saver pane of System Preferences, set Computer sleep: to "Never").

From the point of view of the computer operating system (OS), if using Pure Music's Memory Play, the computer really isn't "doing" anything or "working" during playback, just fetching information from RAM. This is distinct from other player applications such as iTunes, which continually read from the hard disk while music is being played (and that also is true of other player software using iTunes "Ghost Play" to simulate playback in iTunes - but this is playing the file twice to play it once, which is undesirable).

The OS uses disk and (to some extent) CPU activity to determine if the system is idle. Since Pure Music uses far less CPU than other applications, and the disk isn't being accessed during memory play, it is logical for the OS to presume the computer isn't busy or working, and to try to put the system to sleep.

The OS will then attempt to put the system to sleep, but this is intercepted by Pure Music. However during that time, there may be a brief interruption of the sound output. (If the sleep attempt happens at the worst possible time, then it may also affect track sequencing.)

Also, some DACs respond ungracefully if the system is put to sleep. Some will successfully re-establish a connection with Pure Music, but others will not, and only output silence until the DAC is reset (unplugged from the computer then replugged, with Pure Music and iTunes not running).

On older Intel Macs with GMA shared memory graphics, when running in Memory Play mode, it’s possible for the OpenGL texture buffer that’s used for rendering the text to be purged by the OS, in an effort to reclaim RAM. This will cause the text to be rendered at lower resolution, making it appear fuzzy. This is only a cosmetic side effect, and won’t affect the operation of Pure Music. However, this also is an indication that the performance of your computer (and Pure Music) will benefit from having more RAM installed.

In the Advanced pane of the Preferences in iTunes, uncheck the "Keep iTunes Media folder organized" and "Copy files to iTunes media folder..." preferences.

It is easy to find the most recently added tracks if you add a View preference to iTunes (View->View Options) for Date Added, then sort the list with that column.

There was an error in two files posted by 2L of Norway, 2L53SACD_04_stereo_DSD.dff and 2L38_01_DSD.dff that cause Pure Music to hang during the Add operation.

There is an incorrect (off by one) length in one of the header fields. The files were created using a Weiss Saracon (according to the Comment tag).

(Tech info: in the problem files, the chunk size at offset 0x51 for the CMPR tag has an incorrect value of 0x13, when it should be 0x14. This causes the header parsing routine to seek to the wrong offset when scanning for tags.)

2L has posted corrected versions of the files on July 13, 2011 (almost immediately after being notified of the problem).

The built-in optical output of the Mac Pro, as well as all Mac computers introduced before 2010, doesn't support 88.2 kHz. On all Macs the maximum sample rate of the built-in optical output is 96 kHz. (Please see the page Getting Started With Computer Audio for more information on connecting the optical output.)

If you want to play tracks at the native sample rate, you will need a DAC connected via USB or FireWire that supports the file sample rate, or a digital output that provides the native sample rate, such as a USB to coaxial S/PDIF converter, plus a DAC with a digital input that supports the desired sample rate.

Otherwise, the only way to play files with a sample rate not supported by your DAC or digital output setup is via sample rate conversion (upsampling or downsampling).

Note: USB on the Mac supports all common sample rates: 44.1, 48, 88.2, 96, 176.4, 192, 352.8, 384 kHz plus 2.8 MHz (64 Fs DSD) and 5.6 MHz (128 Fs DSD). The supported sample rate depends on the capabilities of the DAC, not on USB.

FLAC file playback in Pure Music requires Memory Play. Downsampling is performed using play-from-disk, but native sample rate playback or upsampling work with Memory Play. However, if downsampling is needed, there are several ways to play your FLAC files if the sample rate isn't supported by your DAC, as described below.

The example below covers playing 88.2 kHz audio tracks if using the optical output of a pre-2010 Mac or Mac Pro, but also applies to audio tracks with other or higher sample rates (that is, when the DAC or playback chain doesn't support the native sample rate of the audio track).

Upsample: Activate the Upsample button to play 88.2 kHz upsampled to 96 kHz.

The Built-In Output must initially be configured in Audio Setup for a "target" rate of 96 kHz - the target sample rate pop-up menu (see attached image) should be set to 96 kHz (don't touch any of the other sample rate menus); then (important) click the Click to Apply Changes button.

Downsample: FLAC playback requires memory play, but downsampling is always done from disk. So, downsampled playback of FLAC files cannot be accomplished at playback time. The file format must be converted, or the file resampled. In order of preference (best sound quality first):

1. Use the File Sample Rate Converter (SRC) feature of Pure Music to create 44.1 kHz (for the optical output; or else select your DAC's highest supported sample rate in the SRC) versions of the FLAC files, then drag them into iTunes. Or,

2. Use the Apple Lossless Converter feature of Pure Music to create Apple Lossless versions of the FLAC files, then drag them into iTunes. They will be downsampled during playback.

Note: if concerned about using Apple Lossless, keep in mind that the compression algorithms used for FLAC and Apple Lossless are essentially identical.

The iTunes shared library feature uses a closed architecture, making it impossible for Pure Music to locate the actual music files so they can be loaded and played using Pure Music's audio engine (the reason for using Pure Music). Pure Music has to be able to find the files to play them (as might be expected). :)

If you wish to use tracks from a shared library, the volume containing the music must be mounted (or "mapped" as called in Windows) locally, and the tracks / folders continaing music added to your iTunes library (drag them to your iTunes Music library in the iTunes application window).

IMPORTANT: Before dragging the tracks, in the Preferences in iTunes, be sure to uncheck the "Copy files to iTunes media folder..." preference to prevent iTunes from physically copying the tracks to your media folder. We also advise unchecking the Keep iTunes Media Folder Organized option.

Mounting the volume is done by using the Finder Go menu (Connect To Server...), by using afp (or smb if the files are hosted on a Windows-based computer or NAS).

IMPORTANT: For Pure Music plus iTunes to locate and play the music tracks, any volumes and hard drives storing music must have unique names. For example, it is OK to have two volumes, one named Music1 and Music2, but not OK to have two volumes with the same name, such as two volumes both named Music.

1. First, the remote computer must be running using an administrator level account, to be able to access all of the volumes from the other computer, and File Sharing must be enabled on both computers (System Preferences -> Sharing control panel). See image above.

2. To mount the remote volume:

- Type the IP address of the remote computer, for example, afp://192.168.0.3 or smb://192.168.0.3 in the Connect to Server window. The address, such as 192.168.0.xx, will depend on your setup, and will be listed in the Network pane of Apple’s System Preferences application on the computer connected to or containing the music storage device.

- Alternatively, click the Browse button. Click on the remote computer in the left of the resulting window (under SHARED), then double click on the volume containing the music to mount it locally after the remote connection is made.

To show the remote volume icon on the Desktop, set the Finder's "General" Preferences to show connected servers.

To automatically mount the remote volume every time the computer is started, select the Accounts control panel in the System Preferences. In the Login Items tab, click the + button, then navigate to the mounted volume, select it, and click Add. Note: do NOT check the check box in the Hide column of the Login Items; this will Hide the mounted item (not what you want to do).

Note: when the Preallocate feature of Pure Music 1.74 or later is used, the Memory Play adjustment dial is hidden, because Pure Music automatically makes the optimum memory play settings for you. Preallocate also significantly improves the efficiency of memory usage while reducing the CPU footprint and minimizing memory fetches.

You can expect a delay of up to several seconds as a track is loaded into memory. If the tracks are being accessed via an Ethernet connection of 100 BT or slower (such as wireless) and a gapless album is being loaded, this may take as long as a few minutes, and is simply a function of the network bandwidth. Compare this to the amount of time it takes to copy the same amount of tracks or files from the server to the local volume. The solution is the same as configuring your computer for faster network performance: use a wired 1000 BT / Gigabit Ethernet connection (and verify that it is operating at 1000baseT speeds in Apple’s Network System Preferences panel; click Advanced, then Ethernet), or else store your music on a hard drive (not the System drive) that’s connected directly to the computer via FireWire, USB2, ATA or SATA. Using the Hybrid Memory Play mode (with sufficient recommended RAM available) can help reduce the delay if playing gapless tracks.

The MEMORY PLAY dial adjusts the amount of available memory you want to dedicate to Memory Play, from 10 to 100 percent. The memory used for Memory Play is allocated dynamically from the available pool of never-used (green) and paged out memory (blue). These are the same default colors used in Apple’s Activity Monitor application, if the latter is set to display the memory usage “pie chart.”

To optimize the performance of the virtual memory system, the best maximum dial setting is at or less than the initial maximum of the “green” memory zone, unless your system disk is a solid state drive. With a solid state drive, the performance penalty resulting from memory paging (more likely with memory in the “blue” zone) is negligible.

The memory play dial setting is based on the fraction of available RAM, instead of a fixed value, to allow the virtual memory system to do its job, while avoiding generating excessive page faults (a bad thing for audio or any realtime task). If other applications are launched after launching Pure Music, the amount of available RAM will be reduced. Therefore, the amount of memory represented by a given dial setting will change dynamically. The maximum amount of RAM will be available immediately after a computer restart.

It’s normal for the relative proportion of “green” and “blue” memory to dynamically change. This is a sign of memory being used at least once (such as Pure Music using it for audio). This will be more evident on computers with less than 4 GB installed RAM. All allocated memory is freed when new tracks are loaded. This can be verified by toggling the MEMORY PLAY button, causing the current track to be reloaded. The amount of free memory will agree with the original value within plus or minus several tens of MB (it’s sometimes more or less, because of the way the virtual memory system works and interacts with other processes running on the computer). Apple’s Activity Monitor application also can be used to monitor RAM usage.

The performance tradeoff in the setting determines how long of a maximum pause you're willing to tolerate during loading music into RAM. If a large track (or group of gapless tracks) is encountered, and you don't mind waiting the extra time for loading, then just set it to maximum. A low setting will not load large tracks above the size threshold into memory, and such tracks will play directly from disk.

From an email to users with questions about the operation of Memory Play: Once memory has been used / touched or paged out it becomes part of the "inactive" pool (a term used by Apple; also see the System Memory tab in the Activity Monitor application for another illustration). This is expected behavior.

However, while the nomenclature of Virtual Memory may at first seem confusing or contradictory, ALL "green" and "blue" memory is still technically "free" and available for use.

The memory setting dial immediately after launching Pure Music should be used as a guide. On a machine with limited physical RAM, it's likely that *all* memory will eventually end up in the "inactive" pool, after using applications like Pure Music that make large memory allocations. Again, that is just a matter of Apple's terminology. This memory is still technically "free" and will be used by Pure Music when needed.
If Pure Music were not releasing memory, it would remain in what's called the Active pool. This can be monitored in the System Memory tab of Apple's Activity Monitor application. The "Real Mem" column in the Activity Monitor window provides additional information, showing the memory used by Pure Music, and this can be used to confirm that memory is properly allocated and released as needed, when new tracks are played. The amount of memory in use will be proportional to the size of the currently playing track (or all the tracks loaded in a group of gapless tracks), and will change dynamically.

Hybrid Memory Play Mode causes the pause at track load time to be independent of the memory play setting, so high settings can be used without long pauses. With gapless tracks, an overlay will be applied to the iTunes application window, to indicate the progress of the track loading operation.

Hog mode works with any audio device / DAC.

If Hog mode apparently is disabled for your DAC, this is because your DAC is assigned as the preferred system sound output device in Audio MIDI Setup (AMS).

Turning off Strict Device Validation in Pure Music's Audio Setup window and clicking Click to Apply Changes, Hog mode will be selectable without changing the AMS setting.

Turning off Strict Device Validation essentially makes Pure Music behave like various other player applications regarding Hog mode. However, Strict Device Validation provides a precautionary "safety belt" that (we believe) is unwisely omitted by the other players. This also is designed to alert you that using Hog mode in a casual way may lead to unexpected system behavior.

Here is what it says in the Pure Music (1.81) User's Guide regarding Hog mode:

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ENABLE EXCLUSIVE ACCESS ("HOG" MODE)

This option reserves the audio device for Pure Music's exclusive use while Pure Music is running.

IMPORTANT: As a precaution, Hog Mode cannot be used for the audio device designated as the preferred device in Apple's Audio MIDI Setup application (AMS). The audio device assigned for Output in AMS should be set to a different device than the one used by Pure Music, to allow iTunes (or other applications) full-time access to an audio output device, if needed. (Just selecting the device in AMS isn't enough; the pop-up "gear" menu must be used to assign the small output "loudspeaker" icon to the device. See instructions under Playthrough for an example of this using the Channel D PAD.)

If using the Built-In audio with a toslink cable, install the Channel D Playthrough Audio Driver (see below) and select it in AMS as a default device. Alternatively, purchase an inexpensive pair of "USB Computer Speakers" and select them in AMS to use for playing system sounds.

Disabling Strict Device Validation in Pure Music will bypass this requirement, but doing so is at your own risk, as it may cause unexpected behavior in iTunes or Pure Music, or other issues.

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(Note: if another player application is running with the device in Hog mode, Hog mode will be disabled in Pure Music. Only one software application at a time can be using a given device / DAC in Hog mode.)

1. Use the Hide Music Server Controls (Music Server menu, command - H) command in Pure Music to hide the user interface. Optionally, Pure Music may then be hidden next (Pure Music menu: Hide Pure Music; but you must hide the music server controls first).

2. Collapse the iTunes window (green button). Optionally, also Hide itunes.

If your DAC supports a 16 bit playback stream (take a look the Format shown in Apple's Audio MIDI Setup (AMS) application), set it to the highest bit depth available, using AMS. This setting only needs to be made once. (Most currently manufactured DACs only support a single bit depth stream format, such as 24 bit, and cannot be changed.)

• Pure Music Less is More Mode; or:
• Animate button off
• Song Info button off
• Upsampling off
• AudioUnit Plug-ins bypassed (if any are enabled, and depending on plug-in)
• Option to update play position in Remote disabled
• Metering button off
• Option to control track play position in iTunes disabled
• Option to update the track play position in iTunes disabled
• Memory Play button on
• Monitor volume Dithering off (or set to Uniform dither if on)
• Pure Music application (control strip / meter bar) in background
• Monitor volume set to 0 dB (audio pass-through without alteration)

Signal paths in Pure Music are special-cased to use the most high-efficiency routines available, depending on the options selected. For example, with the settings above, the audio from the music track(s) is transferred directly from the memory play buffer (RAM), using memory move instructions only. Gain adjustment and metering routines are completely bypassed.

Keyboard commands can be enabled or disabled using the check box in the Preferences window. These commands respond to direct key presses (command key not required) when Pure Music is the frontmost application:

• m = mute
• d = dim
• i = invert absolute polarity
• up arrow = increase volume
• down arrow =  decrease volume
• right arrow = next track (same as in iTunes)
• left arrow = back track (same as in iTunes)
• space bar = toggle play / pause (same as in iTunes)

When using Pure Music, keep in mind that the user interfaces of two applications (both Pure Music and iTunes) are being controlled at once; not just one. iTunes is used to select the music, and Pure Music plays it. Consequently, there is (as expected) a small but sometimes noticeable lag between control inputs, such as initiating play, fast forward, skip back, etc. in iTunes, and when Pure Music responds to the commands. Think of waiting a heartbeat or so.

Besides the above, Memory Play mode (a feature not available in iTunes) imposes a delay of several seconds (depending on the number of tracks and the speed of the data connection, if located on a network drive) after pressing Play, while music track(s) are being loaded. If the media is located on a network volume, a slow network will increase the time needed to load track(s). The interface will be unresponsive during this track loading process.

When using the Server feature, envision how you would use a standalone, hardware based CD player (especially one having a memory play feature, which has the same side effect of delaying playback while the CD is loaded into memory). Press Play, relax, and experience the superb, crystalline, highest possible quality playback available for your music...

Enjoy!