The
esa driver provides support for the ESS Allegro-1 and Maestro-3 audio devices on the PCI bus. These devices are popular in laptop systems.
The Allegro-1 and the Maestro-3 are full-duplex devices that allow independent playback and recording at sample rates between 8000Hz and 48000Hz and are capable of playback at 8 and 16 bit in mono and stereo.
Setting options ESA_NUM_VOICES=4 allows for hardware mixing in the device driver. Note that due to microcode constraints, the
esa driver is currently limited to 4 simultaneous voices.