Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_OpenAudio.3 @ 983:7f08bd66f1ca
Date: Fri, 19 Nov 2004 06:23:53 -0800 (PST)
From: Eric Wing
Subject: OS X Mouse inversion problem fix (again)
Here's yet another patch for the OS X mouse inversion
problem. This should fix the problem once and for all.
I know I've said this before, but *This time for
sure!* :)
If you recall, my last patch broke the non-OpenGL
windowed code and caused the inversion to occur there
instead. Max submitted a patch that partially reverted
the changes back which included the os version hack
which is currently the most recent CVS.
Aaron Sullivan identified and reported to the mailing
list the other day, that the last partial regression
of the code broke OS X 10.2. Looking over the results,
I'm thinking that I was slightly more successful than
I thought at unifying the code. I think I was trying
to unify the code base for OpenGL and non-OpenGL
windowed modes for all versions of the OS. It looks
like I failed at at unifying the OpenGL and non-OpenGL
code, but I did succeed at unifying the OS versions.
Thus, we no longer need the hack for the OS version
checks. The partial regression still included an OS
check which is what broke things for < 10.3.
Attached is the patch for SDL_QuartzWM.m. It basically
is a half-line change that removes one of the two
checks that decides if the mouse coordinates need to
be inverted, i.e:
if (system_version >= 0x1030 &&
(SDL_VideoSurface->flags & SDL_OPENGL) )
becomes this:
if(SDL_VideoSurface->flags & SDL_OPENGL)
With Aaron's outstanding help, we have collectively
tested:
windowed OpenGL
windowed non-OpenGL
fullscreen OpenGL
fullscreen non-OpenGL
under OS X 10.2 (Jaguar), 10.3 (Panther), and 10.4
(Tiger).
We don't have access to 10.0 or 10.1, but since the
original problem didn't materialize until 10.3, I'm
hopeful that testing 10.2 is sufficient. And now that
the code is uniform, I'm also hoping we'll be safe
moving forward to deal with future revisions of the OS
with this issue.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 21 Nov 2004 00:57:47 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
|---|---|
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
1 .TH "SDL_OpenAudio" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_OpenAudio\- Opens the audio device with the desired parameters\&. | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBint \fBSDL_OpenAudio\fP\fR(\fBSDL_AudioSpec *desired, SDL_AudioSpec *obtained\fR); | |
| 9 .SH "DESCRIPTION" | |
| 10 .PP | |
| 11 This function opens the audio device with the \fBdesired\fR parameters, and returns 0 if successful, placing the actual hardware parameters in the structure pointed to by \fBobtained\fR\&. If \fBobtained\fR is NULL, the audio data passed to the callback function will be guaranteed to be in the requested format, and will be automatically converted to the hardware audio format if necessary\&. This function returns -1 if it failed to open the audio device, or couldn\&'t set up the audio thread\&. | |
| 12 .PP | |
| 13 To open the audio device a \fBdesired\fR \fI\fBSDL_AudioSpec\fR\fR must be created\&. | |
| 14 .PP | |
| 15 .nf | |
| 16 \f(CWSDL_AudioSpec *desired; | |
| 17 \&. | |
| 18 \&. | |
| 19 desired=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec));\fR | |
| 20 .fi | |
| 21 .PP | |
| 22 You must then fill this structure with your desired audio specifications\&. | |
| 23 .IP "\fBdesired\fR->\fBfreq\fR" 10The desired audio frequency in samples-per-second\&. | |
| 24 .IP "\fBdesired\fR->\fBformat\fR" 10The desired audio format (see \fI\fBSDL_AudioSpec\fR\fR) | |
| 25 .IP "\fBdesired\fR->\fBsamples\fR" 10The desired size of the audio buffer in samples\&. This number should be a power of two, and may be adjusted by the audio driver to a value more suitable for the hardware\&. Good values seem to range between 512 and 8192 inclusive, depending on the application and CPU speed\&. Smaller values yield faster response time, but can lead to underflow if the application is doing heavy processing and cannot fill the audio buffer in time\&. A stereo sample consists of both right and left channels in LR ordering\&. Note that the number of samples is directly related to time by the following formula: ms = (samples*1000)/freq | |
| 26 .IP "\fBdesired\fR->\fBcallback\fR" 10This should be set to a function that will be called when the audio device is ready for more data\&. It is passed a pointer to the audio buffer, and the length in bytes of the audio buffer\&. This function usually runs in a separate thread, and so you should protect data structures that it accesses by calling \fI\fBSDL_LockAudio\fP\fR and \fI\fBSDL_UnlockAudio\fP\fR in your code\&. The callback prototype is: | |
| 27 .PP | |
| 28 .nf | |
| 29 \f(CWvoid callback(void *userdata, Uint8 *stream, int len);\fR | |
| 30 .fi | |
| 31 .PP | |
| 32 \fBuserdata\fR is the pointer stored in \fBuserdata\fR field of the \fBSDL_AudioSpec\fR\&. \fBstream\fR is a pointer to the audio buffer you want to fill with information and \fBlen\fR is the length of the audio buffer in bytes\&. | |
| 33 .IP "\fBdesired\fR->\fBuserdata\fR" 10This pointer is passed as the first parameter to the \fBcallback\fP function\&. | |
| 34 .PP | |
| 35 \fBSDL_OpenAudio\fP reads these fields from the \fBdesired\fR \fBSDL_AudioSpec\fR structure pass to the function and attempts to find an audio configuration matching your \fBdesired\fR\&. As mentioned above, if the \fBobtained\fR parameter is \fBNULL\fP then SDL with convert from your \fBdesired\fR audio settings to the hardware settings as it plays\&. | |
| 36 .PP | |
| 37 If \fBobtained\fR is \fBNULL\fP then the \fBdesired\fR \fBSDL_AudioSpec\fR is your working specification, otherwise the \fBobtained\fR \fBSDL_AudioSpec\fR becomes the working specification and the \fBdesirec\fR specification can be deleted\&. The data in the working specification is used when building \fBSDL_AudioCVT\fR\&'s for converting loaded data to the hardware format\&. | |
| 38 .PP | |
| 39 \fBSDL_OpenAudio\fP calculates the \fBsize\fR and \fBsilence\fR fields for both the \fBdesired\fR and \fBobtained\fR specifications\&. The \fBsize\fR field stores the total size of the audio buffer in bytes, while the \fBsilence\fR stores the value used to represent silence in the audio buffer | |
| 40 .PP | |
| 41 The audio device starts out playing \fBsilence\fR when it\&'s opened, and should be enabled for playing by calling \fI\fBSDL_PauseAudio\fP(\fB0\fR)\fR when you are ready for your audio \fBcallback\fR function to be called\&. Since the audio driver may modify the requested \fBsize\fR of the audio buffer, you should allocate any local mixing buffers after you open the audio device\&. | |
| 42 .SH "EXAMPLES" | |
| 43 .PP | |
| 44 .nf | |
| 45 \f(CW/* Prototype of our callback function */ | |
| 46 void my_audio_callback(void *userdata, Uint8 *stream, int len); | |
| 47 | |
| 48 /* Open the audio device */ | |
| 49 SDL_AudioSpec *desired, *obtained; | |
| 50 SDL_AudioSpec *hardware_spec; | |
| 51 | |
| 52 /* Allocate a desired SDL_AudioSpec */ | |
| 53 desired=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); | |
| 54 | |
| 55 /* Allocate space for the obtained SDL_AudioSpec */ | |
| 56 obtained=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); | |
| 57 | |
| 58 /* 22050Hz - FM Radio quality */ | |
| 59 desired->freq=22050; | |
| 60 | |
| 61 /* 16-bit signed audio */ | |
| 62 desired->format=AUDIO_S16LSB; | |
| 63 | |
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
64 /* Mono */ |
|
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
65 desired->channels=0; |
|
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
66 |
| 0 | 67 /* Large audio buffer reduces risk of dropouts but increases response time */ |
| 68 desired->samples=8192; | |
| 69 | |
| 70 /* Our callback function */ | |
| 71 desired->callback=my_audio_callback; | |
| 72 | |
| 73 desired->userdata=NULL; | |
| 74 | |
| 75 /* Open the audio device */ | |
| 76 if ( SDL_OpenAudio(desired, obtained) < 0 ){ | |
| 77 fprintf(stderr, "Couldn\&'t open audio: %s | |
| 78 ", SDL_GetError()); | |
| 79 exit(-1); | |
| 80 } | |
| 81 /* desired spec is no longer needed */ | |
| 82 free(desired); | |
| 83 hardware_spec=obtained; | |
| 84 \&. | |
| 85 \&. | |
| 86 /* Prepare callback for playing */ | |
| 87 \&. | |
| 88 \&. | |
| 89 \&. | |
| 90 /* Start playing */ | |
| 91 SDL_PauseAudio(0);\fR | |
| 92 .fi | |
| 93 .PP | |
| 94 .SH "SEE ALSO" | |
| 95 .PP | |
| 96 \fI\fBSDL_AudioSpec\fP\fR, \fI\fBSDL_LockAudio\fP\fR, \fI\fBSDL_UnlockAudio\fP\fR, \fI\fBSDL_PauseAudio\fP\fR | |
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
97 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58 |