playwave.c

SDL_mixer 是一个基于 SDL 的混音器

/*
    PLAYWAVE:  A test application for the SDL mixer library.
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    [e-mail]
*/

/* $Id: playwave.c 2430 2006-05-14 21:07:27Z slouken $ */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#ifdef unix
#include <unistd.h>
#endif

#include "SDL.h"
#include "SDL_mixer.h"


/*
 * rcg06132001 various mixer tests. Define the ones you want.
 */
/*#define TEST_MIX_VERSIONS*/
/*#define TEST_MIX_CHANNELFINISHED*/
/*#define TEST_MIX_PANNING*/
/*#define TEST_MIX_DISTANCE*/
/*#define TEST_MIX_POSITION*/


#if (defined TEST_MIX_POSITION)

#if (defined TEST_MIX_PANNING)
#error TEST_MIX_POSITION interferes with TEST_MIX_PANNING.
#endif

#if (defined TEST_MIX_DISTANCE)
#error TEST_MIX_POSITION interferes with TEST_MIX_DISTANCE.
#endif

#endif


/* rcg06192001 for debugging purposes. */
static void output_test_warnings(void)
{
#if (defined TEST_MIX_CHANNELFINISHED)
	fprintf(stderr, "Warning: TEST_MIX_CHANNELFINISHED is enabled in this binary...\n");
#endif
#if (defined TEST_MIX_PANNING)
	fprintf(stderr, "Warning: TEST_MIX_PANNING is enabled in this binary...\n");
#endif
#if (defined TEST_MIX_VERSIONS)
	fprintf(stderr, "Warning: TEST_MIX_VERSIONS is enabled in this binary...\n");
#endif
#if (defined TEST_MIX_DISTANCE)
	fprintf(stderr, "Warning: TEST_MIX_DISTANCE is enabled in this binary...\n");
#endif
#if (defined TEST_MIX_POSITION)
	fprintf(stderr, "Warning: TEST_MIX_POSITION is enabled in this binary...\n");
#endif
}


static int audio_open = 0;
static Mix_Chunk *wave = NULL;


/* rcg06192001 Check new Mixer version API. */
#if (defined TEST_MIX_VERSIONS)
static void output_versions(const char *libname, const SDL_version *compiled,
							const SDL_version *linked)
{
	fprintf(stderr,
			"This program was compiled against %s %d.%d.%d,\n"
			" and is dynamically linked to %d.%d.%d.\n", libname,
			compiled->major, compiled->minor, compiled->patch,
			linked->major, linked->minor, linked->patch);
}

static void test_versions(void)
{
	SDL_version compiled;
	const SDL_version *linked;

	SDL_VERSION(&compiled);
	linked = SDL_Linked_Version();
	output_versions("SDL", &compiled, linked);

	SDL_MIXER_VERSION(&compiled);
	linked = Mix_Linked_Version();
	output_versions("SDL_mixer", &compiled, linked);
}
#endif


#ifdef TEST_MIX_CHANNELFINISHED  /* rcg06072001 */
static volatile int channel_is_done = 0;
static void channel_complete_callback(int chan)
{
	Mix_Chunk *done_chunk = Mix_GetChunk(chan);
	fprintf(stderr, "We were just alerted that Mixer channel #%d is done.\n", chan);
	fprintf(stderr, "Channel's chunk pointer is (%p).\n", done_chunk);
	fprintf(stderr, " Which %s correct.\n", (wave == done_chunk) ? "is" : "is NOT");
	channel_is_done = 1;
}
#endif


/* rcg06192001 abstract this out for testing purposes. */
static int still_playing(void)
{
#ifdef TEST_MIX_CHANNELFINISHED
	return(!channel_is_done);
#else
	return(Mix_Playing(0));
#endif
}


#if (defined TEST_MIX_PANNING)
static void do_panning_update(void)
{
	static Uint8 leftvol = 128;
	static Uint8 rightvol = 128;
	static Uint8 leftincr = -1;
	static Uint8 rightincr = 1;
	static int panningok = 1;
	static Uint32 next_panning_update = 0;

	if ((panningok) && (SDL_GetTicks() >= next_panning_update)) {
		panningok = Mix_SetPanning(0, leftvol, rightvol);
		if (!panningok) {
			fprintf(stderr, "Mix_SetPanning(0, %d, %d) failed!\n",
					(int) leftvol, (int) rightvol);
			fprintf(stderr, "Reason: [%s].\n", Mix_GetError());
		}

		if ((leftvol == 255) || (leftvol == 0)) {
			if (leftvol == 255)
				printf("All the way in the left speaker.\n");
				leftincr *= -1;
		}

		if ((rightvol == 255) || (rightvol == 0)) {
			if (rightvol == 255)
				printf("All the way in the right speaker.\n");
			rightincr *= -1;
		}

		leftvol += leftincr;
		rightvol += rightincr;
		next_panning_update = SDL_GetTicks() + 10;
	}
}
#endif


#if (defined TEST_MIX_DISTANCE)
static void do_distance_update(void)
{
	static Uint8 distance = 1;
	static Uint8 distincr = 1;
	static int distanceok = 1;
	static Uint32 next_distance_update = 0;

	if ((distanceok) && (SDL_GetTicks() >= next_distance_update)) {
		distanceok = Mix_SetDistance(0, distance);
		if (!distanceok) {
			fprintf(stderr, "Mix_SetDistance(0, %d) failed!\n", (int) distance);
			fprintf(stderr, "Reason: [%s].\n", Mix_GetError());
		}

		if (distance == 0) {
			printf("Distance at nearest point.\n");
			distincr *= -1;
		}
		else if (distance == 255) {
			printf("Distance at furthest point.\n");
			distincr *= -1;
		}

		distance += distincr;
		next_distance_update = SDL_GetTicks() + 15;
	}
}
#endif


#if (defined TEST_MIX_POSITION)
static void do_position_update(void)
{
	static Sint16 distance = 1;
	static Sint8 distincr = 1;
	static Uint16 angle = 0;
	static Sint8 angleincr = 1;
	static int positionok = 1;
	static Uint32 next_position_update = 0;

	if ((positionok) && (SDL_GetTicks() >= next_position_update)) {
		positionok = Mix_SetPosition(0, angle, distance);
		if (!positionok) {
			fprintf(stderr, "Mix_SetPosition(0, %d, %d) failed!\n",
					(int) angle, (int) distance);
			fprintf(stderr, "Reason: [%s].\n", Mix_GetError());
		}

		if (angle == 0) {
			printf("Due north; now rotating clockwise...\n");
			angleincr = 1;
		}

		else if (angle == 360) {
			printf("Due north; now rotating counter-clockwise...\n");
			angleincr = -1;
		}

		distance += distincr;

		if (distance < 0) {
			distance = 0;
			distincr = 3;
			printf("Distance is very, very near. Stepping away by threes...\n");
		} else if (distance > 255) {
			distance = 255;
			distincr = -3;
			printf("Distance is very, very far. Stepping towards by threes...\n");
		}

		angle += angleincr;
		next_position_update = SDL_GetTicks() + 30;
	}
}
#endif


static void CleanUp(int exitcode)
{
	if ( wave ) {
		Mix_FreeChunk(wave);
		wave = NULL;
	}
	if ( audio_open ) {
		Mix_CloseAudio();
		audio_open = 0;
	}
	SDL_Quit();

	exit(exitcode);
}


static void Usage(char *argv0)
{
	fprintf(stderr, "Usage: %s [-8] [-r rate] [-c channels] [-f] [-F] [-l] [-m] <wavefile>\n", argv0);
}


/*
 * rcg06182001 This is sick, but cool.
 *
 *  Actually, it's meant to be an example of how to manipulate a voice
 *  without having to use the mixer effects API. This is more processing
 *  up front, but no extra during the mixing process. Also, in a case like
 *  this, when you need to touch the whole sample at once, it's the only
 *  option you've got. And, with the effects API, you are altering a copy of
 *  the original sample for each playback, and thus, your changes aren't
 *  permanent; here, you've got a reversed sample, and that's that until
 *  you either reverse it again, or reload it.
 */
static void flip_sample(Mix_Chunk *wave)
{
	Uint16 format;
	int channels, i, incr;
	Uint8 *start = wave->abuf;
	Uint8 *end = wave->abuf + wave->alen;

	Mix_QuerySpec(NULL, &format, &channels);
	incr = (format & 0xFF) * channels;

	end -= incr;

	switch (incr) {
		case 8:
			for (i = wave->alen / 2; i >= 0; i -= 1) {
				Uint8 tmp = *start;
				*start = *end;
				*end = tmp;
				start++;
				end--;
			}
			break;

		case 16:
			for (i = wave->alen / 2; i >= 0; i -= 2) {
				Uint16 tmp = *start;
				*((Uint16 *) start) = *((Uint16 *) end);
				*((Uint16 *) end) = tmp;
				start += 2;
				end -= 2;
			}
			break;

		case 32:
			for (i = wave->alen / 2; i >= 0; i -= 4) {
				Uint32 tmp = *start;
				*((Uint32 *) start) = *((Uint32 *) end);
				*((Uint32 *) end) = tmp;
				start += 4;
				end -= 4;
			}
			break;

		default:
			fprintf(stderr, "Unhandled format in sample flipping.\n");
			return;
	}
}


int main(int argc, char *argv[])
{
	int audio_rate;
	Uint16 audio_format;
	int audio_channels;
	int loops = 0;
	int i;
	int reverse_stereo = 0;
	int reverse_sample = 0;

	setbuf(stdout, NULL);    /* rcg06132001 for debugging purposes. */
	setbuf(stderr, NULL);    /* rcg06192001 for debugging purposes, too. */
	output_test_warnings();

	/* Initialize variables */
	audio_rate = MIX_DEFAULT_FREQUENCY;
	audio_format = MIX_DEFAULT_FORMAT;
	audio_channels = 2;

	/* Check command line usage */
	for ( i=1; argv[i] && (*argv[i] == '-'); ++i ) {
		if ( (strcmp(argv[i], "-r") == 0) && argv[i+1] ) {
			++i;
			audio_rate = atoi(argv[i]);
		} else
		if ( strcmp(argv[i], "-m") == 0 ) {
			audio_channels = 1;
		} else
		if ( (strcmp(argv[i], "-c") == 0) && argv[i+1] ) {
			++i;
			audio_channels = atoi(argv[i]);
		} else
		if ( strcmp(argv[i], "-l") == 0 ) {
			loops = -1;
		} else
		if ( strcmp(argv[i], "-8") == 0 ) {
			audio_format = AUDIO_U8;
		} else
		if ( strcmp(argv[i], "-f") == 0 ) { /* rcg06122001 flip stereo */
			reverse_stereo = 1;
		} else
		if ( strcmp(argv[i], "-F") == 0 ) { /* rcg06172001 flip sample */
			reverse_sample = 1;
		} else {
			Usage(argv[0]);
			return(1);
		}
	}
	if ( ! argv[i] ) {
		Usage(argv[0]);
		return(1);
	}

	/* Initialize the SDL library */
	if ( SDL_Init(SDL_INIT_AUDIO) < 0 ) {
		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
		return(255);
	}
	signal(SIGINT, CleanUp);
	signal(SIGTERM, CleanUp);

	/* Open the audio device */
	if (Mix_OpenAudio(audio_rate, audio_format, audio_channels, 4096) < 0) {
		fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
		CleanUp(2);
	} else {
		Mix_QuerySpec(&audio_rate, &audio_format, &audio_channels);
		printf("Opened audio at %d Hz %d bit %s", audio_rate,
			(audio_format&0xFF),
			(audio_channels > 2) ? "surround" :
			(audio_channels > 1) ? "stereo" : "mono");
		if ( loops ) {
		  printf(" (looping)\n");
		} else {
		  putchar('\n');
		}
	}
	audio_open = 1;

#if (defined TEST_MIX_VERSIONS)
    test_versions();
#endif

	/* Load the requested wave file */
	wave = Mix_LoadWAV(argv[i]);
	if ( wave == NULL ) {
		fprintf(stderr, "Couldn't load %s: %s\n",
						argv[i], SDL_GetError());
		CleanUp(2);
	}

	if (reverse_sample) {
		flip_sample(wave);
	}

#ifdef TEST_MIX_CHANNELFINISHED  /* rcg06072001 */
	Mix_ChannelFinished(channel_complete_callback);
#endif

	if ( (!Mix_SetReverseStereo(MIX_CHANNEL_POST, reverse_stereo)) &&
		 (reverse_stereo) )
	{
		printf("Failed to set up reverse stereo effect!\n");
		printf("Reason: [%s].\n", Mix_GetError());
	}

	/* Play and then exit */
	Mix_PlayChannel(0, wave, loops);

	while (still_playing()) {

#if (defined TEST_MIX_PANNING)  /* rcg06132001 */
		do_panning_update();
#endif

#if (defined TEST_MIX_DISTANCE) /* rcg06192001 */
		do_distance_update();
#endif

#if (defined TEST_MIX_POSITION) /* rcg06202001 */
		do_position_update();
#endif

		SDL_Delay(1);

	} /* while still_playing() loop... */

	CleanUp(0);

	/* Not reached, but fixes compiler warnings */
	return 0;
}

/* end of playwave.c ... */