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Hans de Goede 2009-02-13 01:10:52 PST Since the new "glitch free" version of pulseaudio (used in Fedora 10 amongst others), the sound of SDL using apps (like a simple playmus call) has been crackling. While looking in to fixing this I noticed that the current pulseaudio code in SDL uses pa_simple. However pa_simple uses a thread to pump pulseaudio events and ipc, given that SDL already has its own thread for audio handling this is clearly suboptimal, leading to unnecessary context switching IPC, etc. Also pa_simple does not allow one to implement the WaitAudio() callback for SDL audiodrivers properly. Given that my work is mostly a rewrite (although some original pieces remain) I'm attaching the new .c and .h file, as that is easier to review then the huge diff. Let me know if you also want the diff. This new version has the following features: -no longer use an additional thread next to the SDL sound thread -do not crackle with glitch free audio -when used with a newer pulse, which does glitch free audio, the total latency is the same as with the alsa driver -proper WaitAudio() implementation, saving another mixlen worth of latency -adds a WaitDone() implementation This patch has been written in consultancy with Lennart Poetering (the pulseaudio author) and has been reviewed by him for correct use of the pa API. --HG-- branch : SDL-1.2
Simple DirectMedia Layer
(SDL)
Version 1.2
---
http://www.libsdl.org/
This is the Simple DirectMedia Layer, a general API that provides low
level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL,
and 2D framebuffer across multiple platforms.
The current version supports Linux, Windows CE/95/98/ME/XP/Vista, BeOS,
MacOS Classic, Mac OS X, FreeBSD, NetBSD, OpenBSD, BSD/OS, Solaris, IRIX,
and QNX. The code contains support for Dreamcast, Atari, AIX, OSF/Tru64,
RISC OS, SymbianOS, Nintendo DS, and OS/2, but these are not officially
supported.
SDL is written in C, but works with C++ natively, and has bindings to
several other languages, including Ada, C#, Eiffel, Erlang, Euphoria,
Guile, Haskell, Java, Lisp, Lua, ML, Objective C, Pascal, Perl, PHP,
Pike, Pliant, Python, Ruby, and Smalltalk.
This library is distributed under GNU LGPL version 2, which can be
found in the file "COPYING". This license allows you to use SDL
freely in commercial programs as long as you link with the dynamic
library.
The best way to learn how to use SDL is to check out the header files in
the "include" subdirectory and the programs in the "test" subdirectory.
The header files and test programs are well commented and always up to date.
More documentation is available in HTML format in "docs/index.html", and
a documentation wiki is available online at:
http://www.libsdl.org/cgi/docwiki.cgi
The test programs in the "test" subdirectory are in the public domain.
Frequently asked questions are answered online:
http://www.libsdl.org/faq.php
If you need help with the library, or just want to discuss SDL related
issues, you can join the developers mailing list:
http://www.libsdl.org/mailing-list.php
Enjoy!
Sam Lantinga (slouken@libsdl.org)