Open Sound System
OSS 4.x Programmer's Guide

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OSS legacy mixer interface (obsolete)

The original "legacy" mixer API of OSS was developed about 15 years ago to cover the sound cards on the market at that time. Recent computer sound devices have more fine grained mixer and control panel interface that cannot be mapped to the old mixer interface based on a set of "static" control names and numbers. The old interface is still implemented by many of the oldest OSS drivers. However new applications should use the new interface defined in the OSS Mixer Programming section of this manual.

The following ioctl calls and identifiers were part of the old API. You may still see them in many existing OSS drivers and applications. This interface will not be documented in this manual. However older OSS Programmer's guides are still available if you need to use this interface. This is not recommeded since the legacy mixer API will disappear with the devices that still support it.

How to replace the legacy mixer API in audio applications

Audio/media players have traditionally used the legacy mixer API to control certain settings of the audio device. With OSS 4.0 the recording source selection as well as playback and recording level control can be handled locally using features of the audio API. Even the mixer may have controls for these purposes they should not be used from audio applications. You can find the descriptions of the following ioctl calls from the Audio Programming section of this manual.

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