asound

Partial interface for Pascal with static and dynamic linkage, coded with reference to fpalsa etc.

This provides as much functionality as I currently need for emitting warning or acknowledgement « jingles » via a sound card and amplifier using either PCM or a MIDI sequencer device, plus an interface for writing a filter between a MIDI keyboard and sound generator.

It is intended to be lightweight, and to support dynamic linkage for cases where ALSA is unavailable at runtime. As much documentation as possible has been transcribed in a form which the Lazarus IDE will pick up as hints.

The reader is strongly advised to have Lazarus’s project groups addon, to build in the order given and to start reading code with examples/BeepDemoCode noting that this imports AlsaPcmDemo and AlsaSeqDemo.

AlsaPcmDemo imports either AsoundPcm or AsoundPcm_dynamic, with the code being otherwise unchanged.

AlsaSeqDemo imports a crude parser from WatchXyzMidi. WatchXyzMidi imports either AsoundSeq or AsoundSeq_dynamic, with the code being otherwise unchanged.

There is definite scope for improvement in the demo code’s MIDI note sequencing, which suffers from being a hasty transcript of some much older stuff. However as it stands it is sufficient for the author’s requirement, and avoids a substantial amount of overhead inherent in other libraries.

At a lower level there is extra complexity, mostly hidden in include files, which results in the API being presented either as a statically-linked unit or as an object which conceals dynamic linkage. Conveniently, Pascal allows an application program to use identical calling syntax in both cases.

French

Gestion du son et du midi.