Uml MANUAL

ASIO4ALL v2

Universal ASIO Driver For WDM Audio

- Instruction Manual -

Last reviewed: 08/15/08

Table of Contents

Introduction.......................................................................................................................................................1

Getting Started.................................................................................................................................................. 2

Setting up your audio software......................................................................................................................2

Basic Configuration......................................................................................................................................3

Advanced Configuration...................................................................................................................................5

Common Usage Cases Optimizations................................................................................................................8

Using “ReWuschel”.......................................................................................................................................... 9

Troubleshooting.............................................................................................................................................. 10

Introduction

Welcome to ASIO4ALL v2! This manual enables you to make the most of your ASIO4ALL installation,

especially as it comes to the advanced features newly introduced in this Version of ASIO4ALL.

In order to achieve the best possible results with ASIO4ALL, it is recommended that your computer is

configured accordingly:

● Set the power scheme to “Always On” (XP) or “High Performance” (Vista) in order to turn off

Processor P-State switching! Advanced: Modify an existing power scheme so as to not switch CPU

speed, because other power settings are not that critical.

● Turn off system sounds! While e.g. the Windows logon sound certainly will not be a problem,

sound effects in response to button clicks, notifications etc. will mean that for the time they play,

ASIO4ALL may be unable to initialize the audio device.

For updates, help and further information, please visit:

http://www.asio4all.com/ - ASIO4ALL Web site

http://mtippach.proboards40.com/ - Support forum

Getting Started

Setting up your audio software

In order to make use of ASIO4ALL, you need to configure your audio software accordingly. How you would

do this depends on your particular software application. Generally, you would always enter the audio

configuration menu and select ASIO -> ASIO4ALL v2.

There now should be a button to launch the ASIO control panel. How this button is labeled depends on your

particular software. Once you press this button, the ASIO4ALL control panel should appear. Please consult

the manual of your audio software for further assistance, if necessary!

Sometimes, the audio software indeed would not provide an ASIO control panel option. This is the case for

e.g. some ASIO output plugins in media player software. For configuring ASIO4ALL with these

applications anyway, you can launch the control panel by clicking on the ASIO4ALL status icon in the

System Tray area .

The tray icon will become visible whenever an

application initializes the ASIO4ALL driver. If there is

no tray icon, your audio application is not currently

using the ASIO4ALL driver. You can disable balloon

notifications by switching to “Advanced” mode in the

ASIO4ALL control panel.

Note: Where it is possible to access the ASIO control panel from within the audio application, you should

use that option instead of clicking the tray icon!

Changes made in the control sometimes may not have an effect until you restart the audio application. Once

you made it into the ASIO4ALL control panel – one way or the other - you can now proceed with some

basic configuration.

Basic Configuration

1. Device List

This is the list of WDM audio devices found in your system. Highlight the device that you want to make

changes to.

Note: All parameter changes always only apply to the currently highlighted device!

Activate the device you want to use by clicking on the button next to the device name! In the picture

above, the High Definition Audio Device would be enabled while all others are not.

The current state of each device is shown as a small icon on its associated button. It can be either of

these:

Active The device has been successfully started by the audio engine.

Inactive The device should be available for use in this session but has not been started yet

Unavailable The device is in use elsewhere, such as by another audio application or by the

dreaded “MS GS Software Wavetable Synth”, a MIDI output option you

should never use!

Beyond Logic You get this if the device for some unknown reason refuses to start and/or

displays erratic behavior of any kind. Sometimes, closing and re-opening the

control panel may cure the situation, as may unplugging and re-inserting of USB

devices. Sometimes, this can also mean the same as “Unavailable”, whenever the

device does not report its current availability or the lack thereof back to

ASIO4ALL.

Note: If the device list is empty, this means that you do not have a single WDM audio device in your

system. Please check with your audio hardware manufacturer for a WDM driver!

Illustration 1: Basic Control Panel View

2. ASIO Buffer Size

Use the slider to adjust the ASIO buffer size for the device currently highlighted. Smaller buffer size

means lower latency. Once you hear crackles or audio becomes distorted, you need to increase the buffer

size. ASIO buffer size directly relates to audio latency. Thus, you want to get a rather small value here.

3. Load Default Settings

Pressing this button will reset all configuration options to their initial defaults. Use when audio initially

worked and you later got lost in the configuration process.

4. Switch To Advanced Mode

Switches the control panel into “advanced” mode, where you can fix things or completely mess them up

at your disposal. “Advanced” mode is explained in the “Advanced Configuration” section of this

document.

Advanced Configuration

Once the control panel has been switched to advanced mode, things begin to look a little more complicated.

You will have noticed that the items in the device list are now expandable. By expanding the device list, you

can now fully explore the WDM audio architecture of your system.

The device list contains Devices, Device Interfaces and so called “Pins” (this is Microsoft(r) lingo). The

figure above illustrates how they interrelate in the WDM KS hierarchy.

Using the button next to each entry, you can now selectively enable/disable each particular item in the

device list. This way, you can also create multi-device-setups.

Multi-device-setups require that all the devices involved are running from the same clock source. You can

achieve this by daisy-chaining devices via S/PDIF etc. Fortunately, most USB devices will automatically

synchronize themselves for as long as the host controllers they are connected to have a common clock

source, which is trivially true for the USB host controllers embedded in the south bridge on any mainboard.

Note: If devices are not accurately synced, their audio streams are likely to drift apart over time!

On the right side of the panel are the advanced controls (5..9).

5. Latency Compensation

Since ASIO4ALL does not have sufficient knowledge of the underlying hardware/driver architecture, it

can only guess the actual latencies involved.

With these sliders you can compensate for the latencies unknown to ASIO4ALL such that recordings in

your sequencer Software are properly aligned with the rest.

Note: In multi-device-setups the largest respective value of all devices will be used. Therefore, if

different devices have different inherent latencies, audio placement will not be accurate for some devices!

Illustration 2: Advanced Control Panel View

6. Hardware Buffer on/off

Note: For WaveRT drivers (Vista), this box is labeled “Allow Pull Mode (WaveRT)” instead!

Enables the hardware buffer for the highlighted device. This only works for so called “WavePCI”

miniports, as other types of WDM drivers do not usually allow direct access to the hardware buffer.

Adjustment for best hardware buffer performance involves the “ASIO Buffer Size” slider and the “Buffer

Offset” slider (see below). Hardware buffering works best for rather small ASIO buffer sizes. Try

something between 128 and 256 samples as a starter!

The biggest advantage of using the hardware buffer is that this method uses a lot less CPU. In addition, it

may be possible to decrease latencies even further.

In multi-device-setups, it is possible to mix Hardware-buffered devices with devices that are not. This,

however, is not particularly recommended!

If hardware buffering

...