Mercurial > sdl-ios-xcode
view docs/man3/SDL_AudioCVT.3 @ 934:af585d6efec8
Date: Thu, 17 Jun 2004 11:38:51 -0700 (PDT)
From: Eric Wing <ewing2121@yahoo.com>
Subject: New OS X patch (was Re: [SDL] Bug with inverted mouse coordinates in
I have a new patch for OS X I would like to submit.
First, it appears no further action has been taken on
my fix from Apple on the OpenGL windowed mode mouse
inversion problem. The fix would reunify the code, and
no longer require case checking for which version of
the OS you are running. This is probably a good fix
because the behavior with the old code could change
again with future versions of the OS, so those fixes
are included in this new patch.
But in addition, when I was at Apple, I asked them
about the ability to distinguish between the modifier
keys on the left and right sides of the keyboard (e.g.
Left Shift, Right Shift, Left/Right Alt, L/R Cmd, L/R
Ctrl). They told me that starting with Panther, the OS
began supporting this feature. This has always been a
source of annoyance for me when bringing a program
that comes from Windows or Linux to OS X when the
keybindings happened to need distinguishable left-side
and right-side keys. So the rest of the patch I am
submitting contains new code to support this feature
on Panther (and presumably later versions of the OS).
So after removing the OS version checks for the mouse
inversion problem, I reused the OS version checks to
activate the Left/Right detection of modifier keys. If
you are running Panther (or above), the new code will
attempt to distinguish between sides. For the older
OS's, the code path reverts to the original code.
I've tested with Panther on a G4 Cube, G5 dual
processor, and Powerbook Rev C. The Cube and G5
keyboards demonstrated the ability to distinguish
between sides. The Powerbook seems to only have
left-side keys, but the patch was still able to handle
it by producing the same results as before the patch.
I also wanted to test a non-Apple keyboard.
Unfortunately, I don't have any PC USB keyboards.
However, I was able to borrow a Sun Microsystems USB
keyboard, so I tried that out on the G5, and I got the
correct behavior for left and right sides. I'm
expecting that if it worked with a Sun keyboard, most
other keyboards should work with no problems.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Fri, 20 Aug 2004 22:35:23 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_AudioCVT" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" .SH "NAME" SDL_AudioCVT\- Audio Conversion Structure .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ int needed; Uint16 src_format; Uint16 dest_format; double rate_incr; Uint8 *buf; int len; int len_cvt; int len_mult; double len_ratio; void (*filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); int filter_index; } SDL_AudioCVT;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBneeded\fR Set to one if the conversion is possible .TP 20 \fBsrc_format\fR Audio format of the source .TP 20 \fBdest_format\fR Audio format of the destination .TP 20 \fBrate_incr\fR Rate conversion increment .TP 20 \fBbuf\fR Audio buffer .TP 20 \fBlen\fR Length of the original audio buffer in bytes .TP 20 \fBlen_cvt\fR Length of converted audio buffer in bytes (calculated) .TP 20 \fBlen_mult\fR \fBbuf\fR must be \fBlen\fR*\fBlen_mult\fR bytes in size(calculated) .TP 20 \fBlen_ratio\fR Final audio size is \fBlen\fR*\fBlen_ratio\fR .TP 20 \fBfilters[10](\&.\&.)\fR Pointers to functions needed for this conversion .TP 20 \fBfilter_index\fR Current conversion function .SH "DESCRIPTION" .PP The \fBSDL_AudioCVT\fR is used to convert audio data between different formats\&. A \fBSDL_AudioCVT\fR structure is created with the \fI\fBSDL_BuildAudioCVT\fP\fR function, while the actual conversion is done by the \fI\fBSDL_ConvertAudio\fP\fR function\&. .PP Many of the fields in the \fBSDL_AudioCVT\fR structure should be considered private and their function will not be discussed here\&. .IP "\fBUint8 *\fP\fBbuf\fR" 10This points to the audio data that will be used in the conversion\&. It is both the source and the destination, which means the converted audio data overwrites the original data\&. It also means that the converted data may be larger than the original data (if you were converting from 8-bit to 16-bit, for instance), so you must ensure \fBbuf\fR is large enough\&. See below\&. .IP "\fBint\fP \fBlen\fR" 10This is the length of the original audio data in bytes\&. .IP "\fBint\fP \fBlen_mult\fR" 10As explained above, the audio buffer needs to be big enough to store the converted data, which may be bigger than the original audio data\&. The length of \fBbuf\fR should be \fBlen\fR*\fBlen_mult\fR\&. .IP "\fBdouble\fP \fBlen_ratio\fR" 10When you have finished converting your audio data, you need to know how much of your audio buffer is valid\&. \fBlen\fR*\fBlen_ratio\fR is the size of the converted audio data in bytes\&. This is very similar to \fBlen_mult\fR, however when the convert audio data is shorter than the original \fBlen_mult\fR would be 1\&. \fBlen_ratio\fR, on the other hand, would be a fractional number between 0 and 1\&. .SH "SEE ALSO" .PP \fI\fBSDL_BuildAudioCVT\fP\fR, \fI\fBSDL_ConvertAudio\fP\fR, \fI\fBSDL_AudioSpec\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58