view test/threadwin.c @ 942:41a59de7f2ed

Here are patches for SDL12 and SDL_mixer for 4 or 6 channel surround sound on Linux using the Alsa driver. To use them, naturally you need a sound card that will do 4 or 6 channels and probably also a recent version of the Alsa drivers and library. Since the only SDL output driver that knows about surround sound is the Alsa driver, you���ll want to choose it, using: export SDL_AUDIODRIVER=alsa There are no syntactic changes to the programming API. No new library calls, no differences in arguments. There are two semantic changes: (1) For library calls with number of channels as an argument, formerly you could use only 1 or 2 for the number of channels. Now you can also use 4 or 6. (2) The two "left" and "right" arguments to Mix_SetPanning, for the case of 4 or 6 channels, no longer simply control the volumes of the left and right channels. Now the "left" argument is converted to an angle and Mix_SetPosition is called, and the "right" argu- ment is ignored. With two exceptions, so far as I know, the modified SDL12 and SDL_mixer work the same way as the original versions, when opened for 1 or 2 channel output. The two exceptions are bugs which I fixed. Well, the first, anyway, is a bug for sure. When rate conversions up or down by a factor of two are applied (in src/audio/SDL_audiocvt.c), streams with different numbers of channels (that is, mono and stereo) are treated the same way: either each sample is copied or every other sample is omitted. This is ok for mono, but for stereo, it is frames that should be copied or omitted, where by "frame" I mean a portion of the stream containing one sample for each channel. (In the SDL source, confusingly, sometimes frames are called "samples".) So for these rate conversions, stereo streams have to be treated differently, and they are, in my modified version. The other problem that might be characterized as a bug arises when SDL_mixer is passed a multichannel chunk which does not have an integral number of frames. Due to the way the effect_position code loops over frames, when the chunk ends with a partial frame, memory outside the chunk buffer will be accessed. In the case of stereo, it���s possible that because malloc may give more memory than requested, this potential problem never actually causes a segment fault. I don���t know. For 6 channel chunks, I do know, and it does cause segment faults. If SDL_mixer is passed defective chunks and this causes a segment fault, arguably, that���s not a bug in SDL_mixer. Still, whether or not it counts as a bug, it���s easy to protect against, so why not? I added code in mixer.c to discard any partial frame at the end of a chunk. Then what about when SDL or SDL_mixer is opened for 4 or 6 chan- nel output? What happens with the parts of the current library designed for stereo? I don���t know whether I���ve covered all the bases, but I���ve tried: (1) For playing 2 channel waves, or other cases where SDL knows it has to match up a 2 channel source with a 4 or 6 channel output, I���ve added code in SDL_audiocvt.c to make the necessary conversions. (2) For playing midis using timidity, I���ve converted timidity to do 4 or 6 channel output, upon request. (3) For playing mods using mikmod, I put ad hoc code in music.c to convert the stereo output that mikmod produces to 4 or 6 chan- nels. Obviously it would be better to change the mikmod code to mix down into 4 or 6 channels, but I have a hard time following the code in mikmod, so I didn���t do that. (4) For playing mp3s, I put ad hoc code in smpeg to copy channels in the case when 4 or 6 channel output is needed. (5) There seems to be no problem with .ogg files - stereo .oggs can be up converted as .wavs are. (6) The effect_position code in SDL_mixer is now generalized to in- clude the cases of 4 and 6 channel streams. I���ve done a very limited amount of compatibility testing for some of the games using SDL I happen to have. For details, see the file TESTS. I���ve put into a separate archive, Surround-SDL-testfiles.tgz, a couple of 6 channel wave files for testing and a 6 channel ogg file. If you have the right hardware and version of Alsa, you should be able to play the wave files with the Alsa utility aplay (and hear all channels, except maybe lfe, for chan-id.wav, since it���s rather faint). Don���t expect aplay to give good sound, though. There���s something wrong with the current version of aplay. The canyon.ogg file is to test loading of 6 channel oggs. After patching and compiling, you can play it with playmus. (My version of ogg123 will not play it, and I had to patch mplayer to get it to play 6 channel oggs.) Greg Lee <greg@ling.lll.hawaii.edu> Thus, July 1, 2004
author Sam Lantinga <slouken@libsdl.org>
date Sat, 21 Aug 2004 12:27:02 +0000
parents cb40b26523a5
children be9c9c8f6d53
line wrap: on
line source


/* Test out the multi-threaded event handling functions */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "SDL.h"
#include "SDL_thread.h"

/* Are we done yet? */
static int done = 0;

/* Is the cursor visible? */
static int visible = 1;

SDL_Surface *LoadIconSurface(char *file, Uint8 **maskp)
{
	SDL_Surface *icon;
	Uint8       *pixels;
	Uint8       *mask;
	int          mlen, i;

	*maskp = NULL;

	/* Load the icon surface */
	icon = SDL_LoadBMP(file);
	if ( icon == NULL ) {
		fprintf(stderr, "Couldn't load %s: %s\n", file, SDL_GetError());
		return(NULL);
	}

	/* Check width and height */
	if ( (icon->w%8) != 0 ) {
		fprintf(stderr, "Icon width must be a multiple of 8!\n");
		SDL_FreeSurface(icon);
		return(NULL);
	}
	if ( icon->format->palette == NULL ) {
		fprintf(stderr, "Icon must have a palette!\n");
		SDL_FreeSurface(icon);
		return(NULL);
	}

	/* Set the colorkey */
	SDL_SetColorKey(icon, SDL_SRCCOLORKEY, *((Uint8 *)icon->pixels));

	/* Create the mask */
	pixels = (Uint8 *)icon->pixels;
	printf("Transparent pixel: (%d,%d,%d)\n",
				icon->format->palette->colors[*pixels].r,
				icon->format->palette->colors[*pixels].g,
				icon->format->palette->colors[*pixels].b);
	mlen = icon->w*icon->h;
	mask = (Uint8 *)malloc(mlen/8);
	if ( mask == NULL ) {
		fprintf(stderr, "Out of memory!\n");
		SDL_FreeSurface(icon);
		return(NULL);
	}
	memset(mask, 0, mlen/8);
	for ( i=0; i<mlen; ) {
		if ( pixels[i] != *pixels )
			mask[i/8] |= 0x01;
		++i;
		if ( (i%8) != 0 )
			mask[i/8] <<= 1;
	}
	*maskp = mask;
	return(icon);
}

int FilterEvents(const SDL_Event *event)
{
	static int reallyquit = 0;

	switch (event->type) {

		case SDL_ACTIVEEVENT:
			/* See what happened */
			printf("App %s ",
				event->active.gain ? "gained" : "lost");
			if ( event->active.state & SDL_APPACTIVE )
				printf("active ");
			if ( event->active.state & SDL_APPMOUSEFOCUS )
				printf("mouse ");
			if ( event->active.state & SDL_APPINPUTFOCUS )
				printf("input ");
			printf("focus\n");

			/* See if we are iconified or restored */
			if ( event->active.state & SDL_APPACTIVE ) {
				printf("App has been %s\n",
					event->active.gain ?
						 "restored" : "iconified");
			}
			return(0);

		/* This is important!  Queue it if we want to quit. */
		case SDL_QUIT:
			if ( ! reallyquit ) {
				reallyquit = 1;
				printf("Quit requested\n");
				return(0);
			}
			printf("Quit demanded\n");
			return(1);

		/* Mouse and keyboard events go to threads */
		case SDL_MOUSEMOTION:
		case SDL_MOUSEBUTTONDOWN:
		case SDL_MOUSEBUTTONUP:
		case SDL_KEYDOWN:
		case SDL_KEYUP:
			return(1);

		/* Drop all other events */
		default:
			return(0);
	}
}

int HandleMouse(void *unused)
{
	SDL_Event events[10];
	int i, found;
	Uint32 mask;

	/* Handle mouse events here */
	mask = (SDL_MOUSEMOTIONMASK|SDL_MOUSEBUTTONDOWNMASK|SDL_MOUSEBUTTONUPMASK);
	while ( ! done ) {
		found = SDL_PeepEvents(events, 10, SDL_GETEVENT, mask);
		for ( i=0; i<found; ++i ) {
			switch(events[i].type) {
				/* We want to toggle visibility on buttonpress */
				case SDL_MOUSEBUTTONDOWN:
				case SDL_MOUSEBUTTONUP:
					if ( events[i].button.state == SDL_PRESSED ) {
						visible = !visible;
						SDL_ShowCursor(visible);
					}
					printf("Mouse button %d has been %s\n",
						events[i].button.button,
						(events[i].button.state == SDL_PRESSED) ?
						"pressed" : "released");
					break;
				/* Show relative mouse motion */
				case SDL_MOUSEMOTION:
					printf("Mouse relative motion: {%d,%d}\n",
							events[i].motion.xrel, events[i].motion.yrel);
					break;
			}
		}
		/* Give up some CPU to allow events to arrive */
		SDL_Delay(20);
	}
	return(0);
}

int HandleKeyboard(void *unused)
{
	SDL_Event events[10];
	int i, found;
	Uint32 mask;

	/* Handle mouse events here */
	mask = (SDL_KEYDOWNMASK|SDL_KEYUPMASK);
	while ( ! done ) {
		found = SDL_PeepEvents(events, 10, SDL_GETEVENT, mask);
		for ( i=0; i<found; ++i ) {
			switch(events[i].type) {
			    /* We want to toggle visibility on buttonpress */
			    case SDL_KEYDOWN:
			    case SDL_KEYUP:
			    	printf("Key '%c' has been %s\n",
						events[i].key.keysym.unicode,
					(events[i].key.state == SDL_PRESSED) ?
						"pressed" : "released");

			    	/* Allow hitting <ESC> to quit the app */
			    	if ( events[i].key.keysym.sym == SDLK_ESCAPE ) {
			    		done = 1;
			    	}

					/* skip events now that aren't KEYUPs... */
					if (events[i].key.state == SDL_PRESSED)
						break;

			    	if ( events[i].key.keysym.sym == SDLK_f ) {
						int rc = 0;
						printf("attempting to toggle fullscreen...\n");
						rc = SDL_WM_ToggleFullScreen(SDL_GetVideoSurface());
                        printf("SDL_WM_ToggleFullScreen returned %d.\n", rc);
			    	}

			    	if ( events[i].key.keysym.sym == SDLK_g ) {
						SDL_GrabMode m;
						m = SDL_WM_GrabInput(SDL_GRAB_QUERY) == SDL_GRAB_ON ?
								SDL_GRAB_OFF : SDL_GRAB_ON;
						printf("attempting to toggle input grab to %s...\n",
                                m == SDL_GRAB_ON ? "ON" : "OFF");
                        SDL_WM_GrabInput(m);
						printf("attempt finished.\n");
			    	}

			    	break;
			}
		}
		/* Give up some CPU to allow events to arrive */
		SDL_Delay(20);
	}
	return(0);
}

int main(int argc, char *argv[])
{
	SDL_Surface *screen;
	SDL_Surface *icon;
	Uint8 *icon_mask;
	int i, parsed;
	Uint8 *buffer;
	SDL_Color palette[256];
	Uint32 init_flags;
	Uint8  video_bpp;
	Uint32 video_flags;
	SDL_Thread *mouse_thread;
	SDL_Thread *keybd_thread;

	/* Set the options, based on command line arguments */
	init_flags = SDL_INIT_VIDEO;
	video_bpp = 8;
	video_flags = SDL_SWSURFACE;
	parsed = 1;
	while ( parsed ) {
		/* If the threaded option is enabled, and the SDL library hasn't
		   been compiled with threaded events enabled, then the mouse and
		   keyboard won't respond.
		 */
		if ( (argc >= 2) && (strcmp(argv[1], "-threaded") == 0) ) {
			init_flags |= SDL_INIT_EVENTTHREAD;
			argc -= 1;
			argv += 1;
			printf("Running with threaded events\n");
		} else
		if ( (argc >= 2) && (strcmp(argv[1], "-fullscreen") == 0) ) {
			video_flags |= SDL_FULLSCREEN;
			argc -= 1;
			argv += 1;
		} else
		if ( (argc >= 3) && (strcmp(argv[1], "-bpp") == 0) ) {
			video_bpp = atoi(argv[2]);
			argc -= 2;
			argv += 2;
		} else {
			parsed = 0;
		}
	}

	/* Initialize SDL with the requested flags */
	if ( SDL_Init(init_flags) < 0 ) {
		fprintf(stderr,
			"Couldn't initialize SDL: %s\n", SDL_GetError());
		exit(1);
	}
	atexit(SDL_Quit);

	/* Set the icon -- this must be done before the first mode set */
	icon = LoadIconSurface("icon.bmp", &icon_mask);
	if ( icon != NULL ) {
		SDL_WM_SetIcon(icon, icon_mask);
	}
	if ( icon_mask != NULL )
		free(icon_mask);

	/* Initialize the display */
	screen = SDL_SetVideoMode(640, 480, video_bpp, video_flags);
	if (  screen == NULL ) {
		fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n",
						video_bpp, SDL_GetError());
		exit(1);
	}
	printf("Running in %s mode\n", screen->flags & SDL_FULLSCREEN ?
						"fullscreen" : "windowed");

	/* Enable printable characters */
	SDL_EnableUNICODE(1);

	/* Set an event filter that discards everything but QUIT */
	SDL_SetEventFilter(FilterEvents);

	/* Create the event handling threads */
	mouse_thread = SDL_CreateThread(HandleMouse, NULL);
	keybd_thread = SDL_CreateThread(HandleKeyboard, NULL);

	/* Set the surface pixels and refresh! */
	for ( i=0; i<256; ++i ) {
		palette[i].r = 255-i;
		palette[i].g = 255-i;
		palette[i].b = 255-i;
	}
	SDL_SetColors(screen, palette, 0, 256);
	if ( SDL_LockSurface(screen) < 0 ) {
		fprintf(stderr, "Couldn't lock display surface: %s\n",
							SDL_GetError());
		exit(2);
	}
	buffer = (Uint8 *)screen->pixels;
	for ( i=0; i<screen->h; ++i ) {
		memset(buffer,(i*255)/screen->h,
				screen->w*screen->format->BytesPerPixel);
		buffer += screen->pitch;
	}
	SDL_UnlockSurface(screen);
	SDL_UpdateRect(screen, 0, 0, 0, 0);

	/* Loop, waiting for QUIT */
	while ( ! done ) {
		if ( ! (init_flags & SDL_INIT_EVENTTHREAD) ) {
			SDL_PumpEvents(); /* Needed when event thread is off */
		}
		if ( SDL_PeepEvents(NULL, 0, SDL_PEEKEVENT, SDL_QUITMASK) ) {
			done = 1;
		}
		/* Give up some CPU so the events can accumulate */
		SDL_Delay(20);
	}
	SDL_WaitThread(mouse_thread, NULL);
	SDL_WaitThread(keybd_thread, NULL);
	return(0);
}