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14.3. Low level layers

The low level drivers abstract the hardware specific features from the rest of the multimedia code. Those are implemented with a well defined set of APIs, as windows do.

Please note that native low level drivers are not currently supported in Wine, because they either access hardware components or require VxDs to be loaded; Wine does not correctly supports those two so far.

There are two specific low level drivers (msacm.drv for wave input/output, midimap.drv for MIDI output only). These drivers (also present in Windows) allow:

choosing one low level driver between many (we'll discuss how the choice is made later on)
add the possibility to convert stream's format (ie ADPCM => PCM) (this is useful if the format required by the application for playback isn't supported by the soundcard).
add the possibility to filter a stream (adding echo, equalizer... to a wave stream, or modify the instruments that have to be played for a MIDI stream).

14.3.1. Hardware-bound low level drivers

Each low lever driver has to implement at least one of the following functionality, through the named function:

Waveform audio: out for playback, and in for recording. MMSYSTEM and WINMM call the real low level audio driver using the driver's wodMessage and widMessage functions which handle the different requests.
MIDI (Musical Instrument Digital Interface): out for playback, and in for recording. MMSYSTEM and WINMM call the low level driver functions using the driver's midMessage and the modMessage functions.
Mixer: this allows setting the volume for each one of the other functionnality (and also some specific attributes, like left/right balance for stereo >
NextWindowing systemUpCOM in Wine
./usr/share/doc/wine-doc/html/wine-devel/documentation.htm0000644000000000000000000001435610503634103023730 0ustar rootroot00000000000000 Documenting Wine
Wine Developer's Guide
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Chapter 6. Documenting Wine
Table of Contents
6.1. An Overview Of Wine Documentation
6.2. Writing Wine API Documentation
6.3. The Wine DocBook System
This chapter describes how you can help improve Wine's documentation.
Like most large scale volunteer projects, Wine is strongest in areas that are rewarding for its volunteers to work in. The majority of contributors send code patches either fixing bugs, adding new functionality or otherwise improving the software components of the distribution. A lesser number contribute in other ways, such as reporting bugs and regressions, creating tests, providing organizational assistance, or helping to document Wine.
Documentation is important for many reasons, and is often the key to the end user having a successful experience in installing, setting up and using software. Because Wine is a complicated, evolving entity, providing quality up to date documentation is vital to encourage more people to persevere with using and contributing to the project. The following sections describe in detail how to go about adding to or updating Wine's existing documentation.
6.1. An Overview Of Wine Documentation
The Wine source code tree comes with a large amount of documentation in the documentation/ subdirectory. This used to be a collection of text files culled from various places such as the Wine Weekly News and the wine-devel mailing list, but was reorganized some time ago into a number of books, each of which is marked up using SGML. You are reading one of these books (the Wine Developer's Guide) right now.
Since being reorganized, the books have been updated and extended regularly. In their current state they provide a good framework which over time can be expanded and kept up to date. This means that most of the time when further documentation is added, it is a simple matter of updating the content of an already existing file. The books available at the time of writing are:
- The Wine User Guide. This book contains information for end users on installing, configuring and running Wine.
- The Wine Developer's Guide. This book contains information and guidelines for developers and contributors to the Wine project.
- The Winelib User's Guide. This book contains information for developers using Winelib to port Win32 applications to Unix.
- The Wi

14.3. Low level layers

14.3.1. Hardware-bound low level drivers

Chapter 6. Documenting Wine

6.1. An Overview Of Wine Documentation