rockbox/apps/plugins/sdl
Aidan MacDonald 5b27e2255a Add perceptual volume adjustment
The perceived loudness change of a change in volume depends
on the listening volume: at high volumes a 1 dB increment is
noticeable, but at low volumes a larger increment is needed
to get a comparable change in loudness.

Perceptual volume adjustment accounts for this fact, and
divides the hardware volume range into a number of steps.
Each step changes the dB volume by a variable amount, with
most of the steps concentrated at higher volumes. This
makes it possible to sweep over the entire hardware volume
range quickly, without losing the ability to finely adjust
the volume at normal listening levels.

Use "Volume Adjustment Mode" in the system settings menu
to select perceptual volume mode. The number of steps used
is controlled by "Number of Volume Steps". (Number of steps
has no effect in direct adjustment mode.)

It's still possible to set a specific dB volume level from
the sound settings menu when perceptual volume is enabled,
and perceptual volume does not affect the volume displayed
by themes.

Change-Id: I6f91fd3f7c5e2d323a914e47b5653033e92b4b3b
2023-01-22 21:19:57 +00:00
..
include SDL: Silence a large number of compile warnings (WIP) 2020-04-11 19:29:47 +02:00
progs duke3d: allow playing with unofficial data files 2020-08-02 23:54:23 -04:00
SDL_image SDL: Silence a large number of compile warnings (WIP) 2020-04-11 19:29:47 +02:00
SDL_mixer Add perceptual volume adjustment 2023-01-22 21:19:57 +00:00
src sdl: increase default worker thread size. 2021-06-28 02:51:48 +00:00
COPYING
CREDITS
main.c plugins HAVE_BACKLIGHT helper remove ifdefs in favor of dummy functions 2022-11-23 23:00:29 -05:00
NOTES
README
README-SDL.txt
README.Porting
redefines.txt
sdl.make codecs: Add support for the 'VTX' ZX Spectrum chiptunes format. 2020-10-09 11:39:25 -04:00
SOURCES
SOURCES.duke
SOURCES.quake
SOURCES.wolf
wrappers.c

See NOTES for Rockbox-specific porting notes.
The original README is below:

                         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)