在Linux操作系统中编程声音设备实例-红联Linux系统门户

　　Linux下的声音设备编程比大多数人想象的要简单得多。一般说来，我们常用的声音设备是内部扬声器和声卡，它们都对应/dev目录下的一个或多个设备文件，我们象打开普通文件一样打开它们，用ioctl（）函数设置一些参数，然后对这些打开的特殊文件进写操作。

　　由于这些文件不是普通的文件，所以我们不能用ANSI C（标准C）的fopen、fclose等来操作文件，而应该使用系统文件I/O处理函数（open、read、write、lseek和close）来处理这些设备文件。ioctl（）或许是Linux下最庞杂的函数，它可以控制各种文件的属性，在Linux声音设备编程中，最重要的就是使用此函数正确设置必要的参数。

　　下面我们举两个实际的例子来说明如何实现Linux下的声音编程。由于此类编程涉及到系统设备的读写，所以，很多时候需要你有root权限，如果你将下面的例子编译后不能正确执行，那么，首先请你检查是否是因为没有操纵某个设备的权限。

　　对内部扬声器编程内部扬声器是控制台的一部分，所以它对应的设备文件为/dev/console。变量KIOCSOUND在头文件 /usr /include /linux /kd.h中声明，ioctl函数使用它可以来控制扬声器的发声，使用规则为：

引用:
　　ioctl ( fd, KIOCSOUND, (int) tone);

　　fd为文件设备号，tone 是音频值。当tone为0时，终止发声。必须一提的是它所理解的音频和我们平常以为的音频是不同的，由于计算机主板定时器的时钟频率为1.19MHZ，所以要进行正确的发声，必须进行如下的转换：扬声器音频值=1190000/我们期望的音频值。

　　扬声器发声时间的长短我们通过函数usleep（unsigned long usec）来控制。它是在头文件/usr /include /unistd.h中定义的，让程序睡眠usec微秒。下面即是让扬声器按指定的长度和音频发声的程序的完整清单：

引用:
#include < fcntl.h >
#include < stdio.h >
#include < stdlib.h >
#include < string.h >
#include < unistd.h >
#include < sys/ioctl.h >
#include < sys/types.h >
#include < linux/kd.h >

/* 设定默认值 */
#define DEFAULT_FREQ 440 /* 设定一个合适的频率 */
#define DEFAULT_LENGTH 200 /* 200 微秒，发声的长度是以微秒为单位的*/
#define DEFAULT_REPS 1 /* 默认不重复发声 */
#define DEFAULT_DELAY 100 /* 同样以微秒为单位*/

/* 定义一个结构，存储所需的数据*/
typedef struct {
int freq; /* 我们期望输出的频率，单位为Hz */
int length; /* 发声长度，以微秒为单位*/
int reps; /* 重复的次数*/
int delay; /* 两次发声间隔，以微秒为单位*/
} beep_parms_t;

/* 打印帮助信息并退出*/
void usage_bail ( const char *executable_name ) {
printf ( "Usage: \n \t%s [-f frequency] [-l length] [-r reps] [-d delay] \n ",
executable_name );
exit(1);
}

/ * 分析运行参数，各项意义如下：
* "-f <以HZ为单位的频率值 >"
* "-l <以毫秒为单位的发声时长 >"
* "-r <重复次数 >"
* "-d <以毫秒为单位的间歇时长 >"
*/
void parse_command_line(char **argv, beep_parms_t *result) {
char *arg0 = *(argv++);
while ( *argv ) {
if ( !strcmp( *argv,"-f" )) { /*频率*/
int freq = atoi ( *( ++argv ) );
if ( ( freq <= 0 ) | | ( freq > 10000 ) ) {
fprintf ( stderr, "Bad parameter: frequency must be from 1..10000\n" );
exit (1) ;
} else {
result->freq = freq;
argv++;
}
} else if ( ! strcmp ( *argv, "-l" ) ) { /*时长*/
int length = atoi ( *(++argv ) );
if (length < 0) {
fprintf(stderr, "Bad parameter: length must be >= 0\n");
exit(1);
} else {
result->length = length;
argv++;
}
} else if (!strcmp(*argv, "-r")) { /*重复次数*/
int reps = atoi(*(++argv));
if (reps < 0) {
fprintf(stderr, "Bad parameter: reps must be >= 0\n");
exit(1);
} else {
result->reps = reps;
argv++;
}
} else if (!strcmp(*argv, "-d")) { /* 延时 */
int delay = atoi(*(++argv));
if (delay < 0) {
fprintf(stderr, "Bad parameter: delay must be >= 0\n");
exit(1);
} else {
result->delay = delay;
argv++;
}
} else {
fprintf(stderr, "Bad parameter: %s\n", *argv);
usage_bail(arg0);
}
}
}

int main(int argc, char **argv) {
int console_fd;
int i; /* 循环计数器 */
/* 设发声参数为默认值*/
beep_parms_t parms = {DEFAULT_FREQ, DEFAULT_LENGTH, DEFAULT_REPS,
DEFAULT_DELAY};
/* 分析参数，可能的话更新发声参数*/
parse_command_line(argv, &parms);

/* 打开控制台，失败则结束程序*/
if ( ( console_fd = open ( "/dev/console", O_WRONLY ) ) == -1 ) {
fprintf(stderr, "Failed to open console.\n");
perror("open");
exit(1);
}

/* 真正开始让扬声器发声*/
for (i = 0; i < parms.reps; i++) {
/* 数字1190000从何而来，不得而知*/
int magical_fairy_number = 1190000/parms.freq;

ioctl(console_fd, KIOCSOUND, magical_fairy_number); /* 开始发声 */
usleep(1000*parms.length); /*等待... */
ioctl(console_fd, KIOCSOUND, 0); /* 停止发声*/
usleep(1000*parms.delay); /* 等待... */
} /* 重复播放*/
return EXIT_SUCCESS;
}

　　将上面的例子稍作扩展，用户即可以让扬声器唱歌。只要找到五线谱或简谱的音阶、音长、节拍和频率、发声时长、间隔的对应关系就可以了。我现在还记得以前在DOS下编写出《世上只有妈妈好》时的兴奋。最后，说一些提外话，这其实是一个很简单的程序，但是我们却用了很长的篇幅，希望读者从以上的代码里能体会到写好的程序的一些方法，或许最重要的是添加注释吧。一个程序的注释永远不会嫌多，即便你写的时候觉得它根本是多余，但相信我，相信曾这样告诉我们的许多优秀的程序员：养成写很多注释的习惯。

75.108.72.* 于 2007-07-27 03:47:41发表:

blumen hamburg stellingen gaertnerei blumen hamburg stellingen gaertnerei http://www.wedding-flowers-de.info/info/1586.php document cerfa document cerfa http://www.french-law-justice.info/document-cerfa self locking mail box self locking mail box http://www.1gift-cards.info/5/self-locking-mail-box.php dimagrire fiore bach dimagrire fiore bach http://www.vendita-fiori.info/files/dimagrire-fiore-bach.php red white and blue flower red white and blue flower http://www.1-flowersdelivery.info/8/red-white-and-blue-flower.php document vente vehicule document vente vehicule http://www.french-law-lawyer.info/articles/1021.php literature and the writing process 7th edition literature and the writing process 7th edition http://www.law-judgement.info/tools/literature-and-the-writing-process-7th-edition.asp cheap anniversary gift idea cheap anniversary gift idea http://www.cesta-de-regalo1.info/phorum/1279 cane regalo palermo cane regalo palermo http://www.1gift-baskets-it.info/cane-regalo-palermo wicker picnic basket wicker picnic basket http://www.1gift-boxes.info/wicker-picnic-basket.html

24.32.203.* 于 2007-07-27 03:18:05发表:

money tree plant care money tree plant care http://www.1-silkflowers.info/posts/1034.html comprar flor flor burriana comprar flor flor burriana http://www.esflowers.info/1967.asp regalo de empresa barato regalo de empresa barato http://www.es-christmas-gift.info/regalo-de-empresa-barato.asp ley del trabajo en mexico ley del trabajo en mexico http://www.1ley-es.info/article/ley-del-trabajo-en-mexico.php foliage house plant foliage house plant http://www.1-order-flowers.info/articles/foliage-house-plant clasificacion planta ornamental clasificacion planta ornamental http://www.flowers-delivery-es.info/files/1570.html gadget vista tnt gadget vista tnt http://www.fr-baby-gift.info/1497.php carta pacco regalo carta pacco regalo http://www.cesti-regalo-1.info/3/carta-pacco-regalo.html esame di stato avvocato esame di stato avvocato http://www.law-attorney-ita.info/2007/esame-di-stato-avvocato.php colegio de abogado de alicante colegio de abogado de alicante http://www.spanish-law-judgement.info/post/1518

207.42.135.* 于 2007-07-27 00:34:14发表:

cadeaux naissance composition aubeberoi cadeaux naissance composition aubeberoi http://www.1cadeau-anniversaire.info/6/cadeaux-naissance-composition-aubeberoi weihnachtsgeschenk geschenkidee weihnachtsgeschenk geschenkidee http://www.giftgadgets-de.info/weihnachtsgeschenk-geschenkidee.asp baptism gift ideas baptism gift ideas http://www.idea-regalo-1.info/tag/baptism-gift-ideas.html regalo promocionales barcelona regalo promocionales barcelona http://www.es-gift-certificates.info/regalo-promocionales-barcelona.html attorney minnesota tax attorney minnesota tax http://www.law-court-en.info/2/attorney-minnesota-tax.html progetto irrigazione giardino progetto irrigazione giardino http://www.fiori1.info/1400.asp cheque cadeaux compliments universel cheque cadeaux compliments universel http://www.baby-gift-fr.info/pdf/cheque-cadeaux-compliments-universel.php blume gmbh hannover rehten blume gmbh hannover rehten http://www.flowers-online-de.info/today/blume-gmbh-hannover-rehten.php attorney service attorney service http://www.legge-giudice.info/attorney-service.asp baby cool gift shower baby cool gift shower http://www.babygeschenk.info/1058.php

89.84.144.* 于 2007-07-27 00:05:09发表:

corte ingles moda joven corte ingles moda joven http://www.1-ley-justicia.info/1424.asp personalized girl gift personalized girl gift http://www.1babygeschenk.info avocat conseil toulouse avocat conseil toulouse http://www.french-law-justice.info/comment/1302.asp pflanze same pflanze same http://www.1deutsch-blume.info/blog/pflanze-same.html wild flower seed california wild flower seed california http://www.silk-flowers-1.info/1544.html make your own valentine day gift make your own valentine day gift http://www.123gift-baskets.info/10/make-your-own-valentine-day-gift.php shaker heights municipal court shaker heights municipal court http://www.law-lawyer-en.info/1606 nutricion de las planta nutricion de las planta http://www.1envio-de-flores.info/ads/nutricion-de-las-planta.asp modded x box modded x box http://www.giftshop1.info/tag/1540 coltivazione di piante medicinali coltivazione di piante medicinali http://www.123fiori.info/pdf/coltivazione-di-piante-medicinali.asp

216.174.60.* 于 2007-07-26 23:52:23发表:

court tradition court tradition http://www.legge-corte-it.info/online/1323.php water treatment process plant water treatment process plant http://www.12-flower.info/1431.html fiore bach corso firenze fiore bach corso firenze http://www.send-flowers-ita.info/news/fiore-bach-corso-firenze.html california criminal lawyer california criminal lawyer http://www.1-loi-avocat.info/new/california-criminal-lawyer.html soin lotus et fleurs frangipanier soin lotus et fleurs frangipanier http://www.fr-flower-1.info/ads/soin-lotus-et-fleurs-frangipanier.html medical malpractice attorney nyc medical malpractice attorney nyc http://www.legge-corte-it.info/online/1144.php foto fiore ciliegio foto fiore ciliegio http://www.12fiori.info/1/1742.php bank gift card bank gift card http://www.es-baby-gift.info/5/1508 esame avvocato 2006 reggio calabria esame avvocato 2006 reggio calabria http://www.legge-giustizia-it.info/1993.asp baby first birthday gift baby first birthday gift http://www.regalos-bebe.info/book/baby-first-birthday-gift.asp

62.241.83.* 于 2007-07-26 23:50:29发表:

exemple de document unique exemple de document unique http://www.1loi-juge.info/info/1690.asp cane razza regalo cane razza regalo http://www.gift-basket-it.info/ads/cane-razza-regalo.php alabama bankruptcy attorney alabama bankruptcy attorney http://www.1-gesetz-de.info/phorum/1643.asp medecine soin plante granules medecine soin plante granules http://www.fr-wedding-flowers.info/1/1415 ufficio giudice pace scalea ufficio giudice pace scalea http://www.1legge-giustizia-it.info/1/ufficio-giudice-pace-scalea plante d interieur fleurie plante d interieur fleurie http://www.123achatfleurs.info/1606 the black rose the black rose http://www.send-flowers-de.info/ads/the-black-rose.php company mortgage old savannah company mortgage old savannah http://www.1student-loan.info/10/company-mortgage-old-savannah miami personal injury attorney miami personal injury attorney http://www.es-ley-abogado.info/1861.asp bouquet bridal flower silk wedding bouquet bridal flower silk wedding http://www.1-flowers-online.info/bouquet-bridal-flower-silk-wedding.asp

72.36.192.* 于 2007-07-26 17:52:07发表:

72.36.192.* 于 2007-07-26 17:51:40发表:

72.36.192.* 于 2007-07-26 17:50:34发表:

72.36.192.* 于 2007-07-26 17:50:14发表:

72.36.192.* 于 2007-07-26 17:50:02发表:

203.121.73.* 于 2007-07-26 02:04:42发表:

Hi, my sites: :
download free music = FREE MUSIC DOWNLOADS = free mp3 downloads = free music to download = download free music = legal music downloads = Free Music Downloads = download free music = classical music downloads =
http://www.fixgrout.com/cgi/ free country music downloads :: http://musicdownloads4free.angelfire.com/free-music.html FREE MUSIC DOWNLOADS :: http://bridgenews.org/portal_memberdata/portraits/fmusca limewire music downloads :: http://idisk.mac.com/fmp3musicdownloads/Public/free-music.html free download music :: http://musicdownloadsmp3.tripod.com music downloads pc :: http://www.viktorschreckengost.org/portal_memberdata/portraits/bergds music downloads pc :: http://idisk.mac.com/fmp3musicdownloads/Public/music.html FREE MUSIC DOWNLOADS :: http://musicdownloadsmp3.tripod.com/music_downloads.html limewire music downloads :: http://www.fixgrout.com/cgi/ free music download sites :: http://noticeboard.calimera.org/calimera/portal_memberdata/portraits/freemusic download music video :: http://nmstandards.org/portal_memberdata/portraits/vsemoe free music downloads ::
free music downloading .. free music download .. limewire music downloads .. free music download sites .. free music downloading .. free limewire .. free ipod music downloads ..

203.121.69.* 于 2007-07-25 22:36:21发表:

Yhanks you :
limewire music downloads = free music ipods = music download free = free music downloads = free country music downloads = how to download music = mp3 downloads = download free music = free mp3 downloads =
http://www.fixgrout.com/cgi/ download free music :: http://musicdownloads4free.angelfire.com/free-music.html free ipod music downloads sites :: http://bridgenews.org/portal_memberdata/portraits/fmusca music download :: http://idisk.mac.com/fmp3musicdownloads/Public/free-music.html download free music :: http://musicdownloadsmp3.tripod.com free country music downloads :: http://www.viktorschreckengost.org/portal_memberdata/portraits/bergds legal music downloads :: http://idisk.mac.com/fmp3musicdownloads/Public/music.html download free music :: http://musicdownloadsmp3.tripod.com/music_downloads.html music downloads pc :: http://www.fixgrout.com/cgi/ free music downloading :: http://noticeboard.calimera.org/calimera/portal_memberdata/portraits/freemusic music downloads :: http://nmstandards.org/portal_memberdata/portraits/vsemoe Free Music Downloads ::
free mp3 .. FREE MUSIC DOWNLOADS .. music downloads pc .. free ipod music downloads .. free music download sites .. download free music .. free music to download ..

72.36.192.* 于 2007-07-25 18:37:41发表:

72.36.192.* 于 2007-07-25 18:37:14发表:

72.36.192.* 于 2007-07-25 18:36:07发表:

72.36.192.* 于 2007-07-25 18:35:46发表:

72.36.192.* 于 2007-07-25 18:35:32发表:

72.36.192.* 于 2007-07-24 18:28:59发表:

72.36.192.* 于 2007-07-24 18:28:30发表:

72.36.192.* 于 2007-07-24 18:27:29发表:

72.36.192.* 于 2007-07-24 18:27:01发表:

72.36.192.* 于 2007-07-24 18:26:53发表:

72.36.192.* 于 2007-07-23 17:37:01发表:

72.36.192.* 于 2007-07-23 17:36:33发表:

72.36.192.* 于 2007-07-23 17:35:28发表:

72.36.192.* 于 2007-07-23 17:34:57发表:

72.36.192.* 于 2007-07-23 17:34:43发表:

203.121.69.* 于 2007-07-23 16:24:04发表:

Hi boys! :
free country music downloads = download music for free = how to download music = limewire music downloads = download free music = free music downloads = Free Music Downloads = legal music downloads = free ipod music downloads sites =
http://www.fixgrout.com/cgi/ download free music :: http://musicdownloads4free.angelfire.com/free-music.html FREE MUSIC DOWNLOADS :: http://bridgenews.org/portal_memberdata/portraits/fmusca download music video :: http://idisk.mac.com/fmp3musicdownloads/Public/free-music.html limewire :: http://musicdownloadsmp3.tripod.com free limewire :: http://www.viktorschreckengost.org/portal_memberdata/portraits/bergds music :: http://idisk.mac.com/fmp3musicdownloads/Public/music.html free music downloads :: http://musicdownloadsmp3.tripod.com/music_downloads.html music :: http://www.fixgrout.com/cgi/ free music :: http://noticeboard.calimera.org/calimera/portal_memberdata/portraits/freemusic music downloads :: http://nmstandards.org/portal_memberdata/portraits/vsemoe download free music ::
free music download sites .. free ipod music downloads .. music download .. free music ipods .. free ipod music downloads sites .. FREE MUSIC DOWNLOADS .. free mp3 downloads ..

203.121.69.* 于 2007-07-23 15:43:02发表:

Yhanks! :
free mp3 music downloads = free mp3 music downloads = free music for ipod = download music free = free ipod music downloads = free legal music downloads = free music for ipod = free music download sites = free music to download =
http://www.fixgrout.com/cgi/ free limewire :: http://musicdownloads4free.angelfire.com/free-music.html free legal music downloads :: http://bridgenews.org/portal_memberdata/portraits/fmusca Free Music Downloads :: http://idisk.mac.com/fmp3musicdownloads/Public/free-music.html free music download :: http://musicdownloadsmp3.tripod.com free music downloads :: http://www.viktorschreckengost.org/portal_memberdata/portraits/bergds free country music downloads :: http://idisk.mac.com/fmp3musicdownloads/Public/music.html free ipod music downloads sites :: http://musicdownloadsmp3.tripod.com/music_downloads.html music download :: http://www.fixgrout.com/cgi/ music download :: http://noticeboard.calimera.org/calimera/portal_memberdata/portraits/freemusic limewire music downloads :: http://nmstandards.org/portal_memberdata/portraits/vsemoe free music downloading ::
free music .. free music video .. download music video .. download free music .. download free music .. free music download .. classical music downloads ..

203.121.69.* 于 2007-07-23 15:11:07发表:

Great! Best free mp3 music downloads site: :
free music to download = download music video = how to download music = free mp3 = free legal music downloads = music downloads pc = free mp3 music downloads = free music downloads = limewire music downloads =
http://www.fixgrout.com/cgi/ Free Music Downloads :: http://musicdownloads4free.angelfire.com/free-music.html download music video :: http://bridgenews.org/portal_memberdata/portraits/fmusca download free music :: http://idisk.mac.com/fmp3musicdownloads/Public/free-music.html download music for free :: http://musicdownloadsmp3.tripod.com download free music :: http://www.viktorschreckengost.org/portal_memberdata/portraits/bergds limewire music downloads :: http://idisk.mac.com/fmp3musicdownloads/Public/music.html free limewire :: http://musicdownloadsmp3.tripod.com/music_downloads.html music downloads :: http://www.fixgrout.com/cgi/ music downloads pc :: http://noticeboard.calimera.org/calimera/portal_memberdata/portraits/freemusic Free Music Downloads :: http://nmstandards.org/portal_memberdata/portraits/vsemoe mp3 downloads ::
limewire music downloads .. free ipod music downloads sites .. how to download music .. free music downloading .. legal music downloads .. free mp3 downloads .. free mp3 downloads ..

72.36.192.* 于 2007-07-22 18:04:05发表:

72.36.192.* 于 2007-07-22 18:03:38发表:

72.36.192.* 于 2007-07-22 18:02:33发表:

72.36.192.* 于 2007-07-22 18:02:14发表:

72.36.192.* 于 2007-07-22 18:02:01发表:

72.36.192.* 于 2007-07-21 19:45:23发表:

72.36.192.* 于 2007-07-21 19:44:51发表:

72.36.192.* 于 2007-07-21 19:43:49发表:

72.36.192.* 于 2007-07-21 19:43:17发表:

在Linux操作系统中编程声音设备实例

共有 2236 条评论

频道文章

最新教程

随机推荐