Audio from PCs – in the Beginning…

At first, personal computers did not have audio devices installed or built in, other than the very basic speaker which has a connection using two leads that go to the system motherboard. Audio files did not exist at the time, and there were no software programs to play music. The basic speaker set up was used for the Power On Self Test as well as application alerts. There were some developers who designed applications that did allow small amounts of music to be played, but these were not common.

In the early 1990s, it became popular to use consumer grade add-in audio cards, and at first there were devices, including SoundBlaster by Creative Labs, which used eight bit Industry Standard Architecture. These cards were fairly cheap compared to higher end cards becoming available, but they relied on the system CPU for most of the processing for audio and this put a limit on the capabilities of the card, plus made the load bigger for the system. Other companies, including Turtle Beach, were busy with the development of audio cards which were a higher grade, and were intended for musicians and other music professionals.

As technology improved, so did audio drivers and sound cards. Newer sound cards used on-board audio processing CPUs, which removed most of the load from the CPU of the computer, and these cards began to support higher bit rates including thirty two, sixty four, and then one hundred and twenty eight bits. Since the year 2000, multi-channel cards which have the capability of supporting surround sound, and other requirements that have become common.

With Windows systems, audio device access is managed by the operating system. It is impossible for one application to take total control of the audio device, and this makes it possible for multiple applications to simultaneously send output to the audio device installed. This could not be done with DOS or Windows 3.1 systems.

Both Turtle Beach and Creative Labs are still the leading manufacturers of the after-market sound cards available. A lot of motherboards available currently incorporate built-in audio devices that have 5 or 7-channels. PC users have the option available to disable these devices, normally using the BIOS settings, if the user prefers a higher end device instead. Current versions of Windows and Plug-and-Play hardware allows for the automatic detection of any newly installed audio cards on the system, as well as any other peripherals installed. It is normally possible to simply plug in the device and it will function correctly.

There are a large number of different audio drivers available. These include the Delta series, FireWire series, keyboard series, mouse series, USB audio series, the Revolution series, the Legacy series, the Omni series, the Headphone series, the Software series, and many more. The number of audio drivers available can be in the thousands, and it is important to make sure the driver and operating system are compatible when downloading audio drivers for them to function correctly.

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ASIO offers a high appeal to the professional music market because of the properties integrated, including high fidelity and low latency. ASIO goes right past the many layers of OS software and processing and instead goes straight from the application being run to the sound card. Because the various layers are bypassed, delays are minimized and the latency is reduced. Because there is a direct path that is high speed, there is a higher fidelity sound involved.

ASIO – How It All Began…

ASIO is the pet project of a leading personal computer third party developer named Steinberg. During the mid 1980s, ASIO was first started with a passionate interest in music and a Commodore 64 machine. As technology relating to computers evolved, Steinberg was a moving force to bringing PCs and music together. The Cubase software program allows music production to be brought to the personal computer and rapidly rose to a major competitor to analog tape equipment. In 1995, WaveLab was introduced by Steinberg, and is an essential online editing tool for audio files that is used by numerous professional musicians.

ASIO was released in 1997, and was an open standard combined with Virtual Studio Technology. ASIO is the core of the Virtual Studio technology, and it supports both variable bit depths and sample rates,multi-channel operation,and synchronization. Many hardware manufacturers besides Steinberg have adopted ASIO. This standard offers high fidelity, low latency, easy use, and stable audio capabilities.

Pinnacle Systems acquired Steinberg, then Yamaha acquired Pinnacle systems, but the Steinberg name still lives on, just as the ASIO standard does. There was a product introduced in 2007 called Sequel that allows entry level PC users to use professional level audio technology.

Not All ASIO Drivers are Created Equal

When downloading and installing ASIO drivers, make sure that the driver and the operating system or application is compatible. This is not always the case, such as with the Digidesign ASIO Driver 6.1.1 and the application Pro Tools TDM 6.2 or lower, or if Pro Tools LE version 6.1 or lower is installed on the system. If the Pro Tools LE 6.1 or a lower version is installed on the system, remove it with the Add or Remove Programs Control Panel, then install the latest version to prevent problems with some ASIO drivers.

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Intel developed this codec so developers could build in high quality audio devices on a PC, which could deliver a 96kHz/20bit playback in stereo mode and a 48kHz/20bit playback in multichannel mode. However, this codec is now almost obsolete due to the introduction of the Intel High Definition Audio, which was introduced in 2004.

AC97 drivers follow the AC97 development standards. AC97 addressed the standards for Input/Output as well, for modems with MC87, a modem codec and AMC97, a codec for the modem and audio combined. MC87 and AMC97 are included in the component specification for AC97 drivers.

The AC97 standard includes many features which are typical. The capability for Comprehensive Power Management, the ability for mono outlet used with a speaker phone, a mono speaker outlet that is internal, analog stereo input capability of one to four, analog mono input capability of one to two, stereo audio that is sixteen bit full duplex, stereo output that is both dedicated and auxiliary, CD input that is high quality analog, pinout assignments that are in a forty eight pin QFP package, and MIC input which features a twenty dB boost, an AEC reference capability, and a programmable gain.

The AC97 standard also defines optional features included. There are controls available for loudness and tone, enhancements to three dimensional stereo are included, an output for headphones, the capability to sense a jack, the capability to report, resolution options that include eighteen or twenty bit, and digital output utilizing a transmitter that is an Integrated Sony/Philips Digital Interface.

The AC Link is the digital link that allows the AC97 digital controller to be connected to the AC97 codec. An AC Link is a bi-directional TDM format interface that contains five wires, and will support the connections of a maximum of four codecs on one single card or circuit board.

AC97 supports many different audio outputs, including amplified stereo headphone, analog 6-channel support for both front and Surround Sound personal computer speaker systems, analog stereo, Surround Sound that is analog matrix-encoded for home theater systems, and a digital output 5.1 channel for home theater systems.

The codec AC97 will not always involve coverage of the AC97 Digital Controller, and AC97 drivers are used instead, which are developed following the standards for AC97 by vendors of the controllers. This codec also allows the specification of clocking, signals, pin assignments, addressing, power management, strapping, protocol, sample rates, behavior, slot assignments, performance characteristics, and many others.

The AC97 standard was a big step in audio devices for the PC which were standardized. Today though, computer usage has changed. The AC97 drivers and standards were developed when the audio was needed just to listen to music or watch a DVD movie once in a while. Now consumers are used to audio formats with multiple channels in full surround sound systems that include six to eight speakers. Because of the new computer audio requirements, the Intel HD Audio codec was developed to replace the AC97 drivers and standards. New computers allow the generation of many audio and video streams from one PC, and AC97 does not have these capabilities.

It is possible to download AC97 drivers from a variety of sources, and not all will include the AC97 drivers from Intel. There are a number of generic drivers that can be found and uploaded online, and roughly two thirds of PC users who have AC97 drivers use a generic version for their audio needs. It is possible to find AC97 drivers for almost every operating system, including Windows, so make sure the driver and operating system are compatible with one another before installing the driver. For example, some AC97 drivers, such as the ICH AC97 Driver, which is a BE operating system sound driver, do not support Windows, but does support many SIS, Intel, and NVIDIA chip sets.

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