C 使用libao播放音频文件

我试图让一个简单的C程序播放AIFF或WAV文件。根据我在上所看到的，这应该是可行的，但不管我输入什么文件，它都会发出嗡嗡声。这个怎么了

/* compile with "gcc -o playme playme.c -lao -ldl -lm" */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ao/ao.h>
#include <math.h>

ao_device *device;
ao_sample_format format;

int main(int argc, char *argv[])
{
    int default_driver;
    char *buffer;
    unsigned long count;

    FILE *fp;

    if (argc != 2) {
    printf("usage: %s <filename>\n", argv[0]);
    exit(1);
    }

    ao_initialize();
    default_driver = ao_default_driver_id();
    memset(&format, 0, sizeof(format));

    format.bits = 16;
    format.channels = 2;
    format.rate = 44100;
    format.byte_format = AO_FMT_LITTLE;

    device = ao_open_live(default_driver, &format, NULL /* no options */);
    if (device == NULL) {
        printf("Error opening sound device.\n");
        exit(1);
    }

    fp = fopen(argv[1], "rb");
    if (fp == NULL) {
    printf("Cannot open %s.\n", argv[1]);
    exit(2);
    }

    fseek(fp, 0, SEEK_END);
    count = ftell(fp);
    fseek(fp, 0, SEEK_SET);

    fread(buffer, sizeof(char), count, fp);
    ao_play(device, buffer, count);
    ao_close(device);
    ao_shutdown();

    return 0;
}

/*使用“gcc-o playme playme.c-lao-ldl-lm”编译*/
#包括
#包括
#包括
#包括
#包括
ao_装置*装置；
ao_样本_格式；
int main（int argc，char*argv[]）
{
int默认_驱动程序；
字符*缓冲区；
无符号长计数；
文件*fp；
如果（argc！=2）{
printf（“用法：%s\n”，argv[0]）；
出口（1）；
}
ao_初始化（）；
default_driver=ao_default_driver_id（）；
memset（&format，0，sizeof（format））；
format.bits=16；
format.channels=2；
format.rate=44100；
format.byte\u format=AO\u FMT\u LITTLE；
device=ao_open_live（默认_驱动程序和格式，NULL/*无选项*/）；
如果（设备==NULL）{
printf（“打开声音设备时出错。\n”）；
出口（1）；
}
fp=fopen（argv[1]，“rb”）；
如果（fp==NULL）{
printf（“无法打开%s。\n”，argv[1]）；
出口（2）；
}
fseek（fp，0，SEEK_END）；
计数=ftell（fp）；
fseek（fp，0，SEEK_集）；
fread（缓冲区，大小（字符），计数，fp）；
ao_播放（设备、缓冲区、计数）；
ao_关闭（装置）；
AOU关机（）；
返回0；
}

我没有意识到的一个关键问题是，李宝绝对不会解码。因此，在打开音频设备之前，由程序员提取样本大小、速率、频道等，并将其提供给libao。libsndfile可用于执行此操作，但如果您只是想要快速且肮脏的内容，则以下是播放AIFF文件的代码：

/* compile with "gcc -o playaiff playaiff.c -lao -ldl -lm" */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ao/ao.h>
#include <math.h>

#define MAXCHAN 8

ao_device *device;
ao_sample_format format;

#define gshort( b) (((int)((b)[0]) << 8) + (int)((b)[1]))
#define glong( b) (((int)((b)[0]) << 24) + ((int)((b)[1]) << 16) +\
        ((int)((b)[2]) << 8) + (int)((b)[3]))

typedef struct {
    short     channels;
    short     samplesize;
    int   samplerate;
    unsigned long samplecount;
    int       valid;
} aiffinfo;

aiffinfo getaiffinfo(FILE *);
static int IeeeExtendedToLong(unsigned char *);

int main(int argc, char *argv[])
{
    int default_driver;
    char *buffer;

    aiffinfo info;

    FILE *fp;

    if (argc != 2) {
    printf("usage: %s <filename>\n", argv[0]);
    exit(1);
    }

    ao_initialize();
    default_driver = ao_default_driver_id();
    memset(&format, 0, sizeof(format));

    fp = fopen(argv[1], "rb");
    if (fp == NULL) {
    printf("Cannot open %s.\n", argv[1]);
    exit(2);
    }

    info = getaiffinfo(fp);

    if (!info.valid) {
    printf("Invalid AIFF file.\n");
    exit(1);
    }

    format.bits = info.samplesize;
    format.channels = info.channels;
    format.rate = info.samplerate;
    format.byte_format = AO_FMT_LITTLE;

    device = ao_open_live(default_driver, &format, NULL /* no options */);
    if (device == NULL) {
        printf("Error opening sound device.\n");
        exit(1);
    }

    buffer = malloc(sizeof(char) * info.samplecount);

    fread(buffer, sizeof(char), info.samplecount, fp);
    ao_play(device, buffer, info.samplecount);
    ao_close(device);
    ao_shutdown();

    return 0;
}


aiffinfo getaiffinfo(FILE *fp)
{
    int size;
    int len;
    int offset;
    int blocksize;
    int found = 0;
    unsigned char chunk[18];
    unsigned char fid[4];
    aiffinfo info;

    info.samplesize = 0;
    info.valid = 0;

    if (fread(chunk, 1, 4, fp) < 4) return info;
    if (memcmp(chunk,"FORM",4)) return info;
    if (fread(chunk, 1, 4, fp) < 4)  return info;
    size = glong(chunk);
    if (size & 1) size++;
    if (size < 20) return info;
    if (fread(chunk, 1, 4, fp) < 4) return info;
    if (memcmp(chunk, "AIFF", 4)) return info;

    size -= 4;
    while (size > 8) {
    if (fread(fid, 1, 4, fp) < 4) return info;    // chunck id
    if (fread(chunk, 1, 4, fp) < 4) return info;    // and len
    size -= 8;
    len = glong(chunk);
    if (len < 0) return info;
    if (len & 1) len++;
    size -= len;
    if (size < 0) return info;
    if (memcmp(fid, "COMM", 4) == 0) {
        if (len != 18) return info;
        if (fread(chunk, 1, 18, fp) < 18) return info;
        info.channels = gshort(chunk);
        if (info.channels < 1) return info;
        if (info.channels > MAXCHAN) return info;
        info.samplecount = glong(chunk+2);
        if (info.samplecount < 1) return info;
        info.samplerate = IeeeExtendedToLong(chunk + 8);
        if (info.samplerate <= 0) return info;
        info.samplesize = gshort(chunk + 6);
        if (info.samplesize < 1 || info.samplesize > 16) return info;
    } else if (memcmp(fid,"SSND",4)==0){
        if (!info.channels) return info;
        if (fread(chunk, 1, 4, fp) < 4) return info;
        offset = glong(chunk);
        if (fread(chunk, 1, 4, fp) < 4) return info;
        blocksize = glong(chunk);
        if (blocksize) return info;
        if (offset) fseek(fp, offset,SEEK_CUR);
        found = 1;
        break;
    } else fseek (fp, len, SEEK_CUR);
    }

    if (!found) return info;
    if (!info.channels) return info;

//    printf("Looks good so far.\n");
    info.valid = 1;
    return info;
}


/****************************************************************
 * Extended precision IEEE floating-point conversion routine.
 ****************************************************************/

#ifndef Uint32
#define Uint32 unsigned int
#endif
#ifndef HUGE_INT32
#define HUGE_INT32 0x7fffffff
#endif                                          /* HUGE_VAL */

static int IeeeExtendedToLong( unsigned char *bytes)
{
    int f = 0;
    int expon;
    Uint32 hiMant;
    Uint32 loMant;

    expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
    hiMant = ((Uint32) (bytes[2] & 0xFF) << 24)
    | ((Uint32) (bytes[3] & 0xFF) << 16)
    | ((Uint32) (bytes[4] & 0xFF) << 8)
    | ((Uint32) (bytes[5] & 0xFF));
    loMant = ((Uint32) (bytes[6] & 0xFF) << 24)
    | ((Uint32) (bytes[7] & 0xFF) << 16)
    | ((Uint32) (bytes[8] & 0xFF) << 8)
    | ((Uint32) (bytes[9] & 0xFF));

    if (expon == 0 && hiMant == 0 && loMant == 0) f = 0;
    else if (expon == 0x7FFF) f = HUGE_INT32;
    else {
    expon -= 16382;
    expon = 32-expon;
    if (expon < 0) f = HUGE_INT32;
    else f = hiMant >> expon;
    }

    if (bytes[0] & 0x80)
    return -f;
    else
    return f;
}

/*使用“gcc-o playaiff playaiff.c-lao-ldl-lm”编译*/
#包括
#包括
#包括
#包括
#包括
#定义MAXCHAN 8
ao_装置*装置；
ao_样本_格式；
#定义gshort（b）（（int）（（b）[0]）我没有意识到的一个关键问题是，libao绝对不进行解码。因此，在打开音频设备之前，由程序员提取样本大小、速率、频道等，并将其提供给libao。libsndfile可用于执行此操作，但如果您只想快速而肮脏的操作，下面是播放A的代码IFF文件：

/* compile with "gcc -o playaiff playaiff.c -lao -ldl -lm" */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ao/ao.h>
#include <math.h>

#define MAXCHAN 8

ao_device *device;
ao_sample_format format;

#define gshort( b) (((int)((b)[0]) << 8) + (int)((b)[1]))
#define glong( b) (((int)((b)[0]) << 24) + ((int)((b)[1]) << 16) +\
        ((int)((b)[2]) << 8) + (int)((b)[3]))

typedef struct {
    short     channels;
    short     samplesize;
    int   samplerate;
    unsigned long samplecount;
    int       valid;
} aiffinfo;

aiffinfo getaiffinfo(FILE *);
static int IeeeExtendedToLong(unsigned char *);

int main(int argc, char *argv[])
{
    int default_driver;
    char *buffer;

    aiffinfo info;

    FILE *fp;

    if (argc != 2) {
    printf("usage: %s <filename>\n", argv[0]);
    exit(1);
    }

    ao_initialize();
    default_driver = ao_default_driver_id();
    memset(&format, 0, sizeof(format));

    fp = fopen(argv[1], "rb");
    if (fp == NULL) {
    printf("Cannot open %s.\n", argv[1]);
    exit(2);
    }

    info = getaiffinfo(fp);

    if (!info.valid) {
    printf("Invalid AIFF file.\n");
    exit(1);
    }

    format.bits = info.samplesize;
    format.channels = info.channels;
    format.rate = info.samplerate;
    format.byte_format = AO_FMT_LITTLE;

    device = ao_open_live(default_driver, &format, NULL /* no options */);
    if (device == NULL) {
        printf("Error opening sound device.\n");
        exit(1);
    }

    buffer = malloc(sizeof(char) * info.samplecount);

    fread(buffer, sizeof(char), info.samplecount, fp);
    ao_play(device, buffer, info.samplecount);
    ao_close(device);
    ao_shutdown();

    return 0;
}


aiffinfo getaiffinfo(FILE *fp)
{
    int size;
    int len;
    int offset;
    int blocksize;
    int found = 0;
    unsigned char chunk[18];
    unsigned char fid[4];
    aiffinfo info;

    info.samplesize = 0;
    info.valid = 0;

    if (fread(chunk, 1, 4, fp) < 4) return info;
    if (memcmp(chunk,"FORM",4)) return info;
    if (fread(chunk, 1, 4, fp) < 4)  return info;
    size = glong(chunk);
    if (size & 1) size++;
    if (size < 20) return info;
    if (fread(chunk, 1, 4, fp) < 4) return info;
    if (memcmp(chunk, "AIFF", 4)) return info;

    size -= 4;
    while (size > 8) {
    if (fread(fid, 1, 4, fp) < 4) return info;    // chunck id
    if (fread(chunk, 1, 4, fp) < 4) return info;    // and len
    size -= 8;
    len = glong(chunk);
    if (len < 0) return info;
    if (len & 1) len++;
    size -= len;
    if (size < 0) return info;
    if (memcmp(fid, "COMM", 4) == 0) {
        if (len != 18) return info;
        if (fread(chunk, 1, 18, fp) < 18) return info;
        info.channels = gshort(chunk);
        if (info.channels < 1) return info;
        if (info.channels > MAXCHAN) return info;
        info.samplecount = glong(chunk+2);
        if (info.samplecount < 1) return info;
        info.samplerate = IeeeExtendedToLong(chunk + 8);
        if (info.samplerate <= 0) return info;
        info.samplesize = gshort(chunk + 6);
        if (info.samplesize < 1 || info.samplesize > 16) return info;
    } else if (memcmp(fid,"SSND",4)==0){
        if (!info.channels) return info;
        if (fread(chunk, 1, 4, fp) < 4) return info;
        offset = glong(chunk);
        if (fread(chunk, 1, 4, fp) < 4) return info;
        blocksize = glong(chunk);
        if (blocksize) return info;
        if (offset) fseek(fp, offset,SEEK_CUR);
        found = 1;
        break;
    } else fseek (fp, len, SEEK_CUR);
    }

    if (!found) return info;
    if (!info.channels) return info;

//    printf("Looks good so far.\n");
    info.valid = 1;
    return info;
}


/****************************************************************
 * Extended precision IEEE floating-point conversion routine.
 ****************************************************************/

#ifndef Uint32
#define Uint32 unsigned int
#endif
#ifndef HUGE_INT32
#define HUGE_INT32 0x7fffffff
#endif                                          /* HUGE_VAL */

static int IeeeExtendedToLong( unsigned char *bytes)
{
    int f = 0;
    int expon;
    Uint32 hiMant;
    Uint32 loMant;

    expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
    hiMant = ((Uint32) (bytes[2] & 0xFF) << 24)
    | ((Uint32) (bytes[3] & 0xFF) << 16)
    | ((Uint32) (bytes[4] & 0xFF) << 8)
    | ((Uint32) (bytes[5] & 0xFF));
    loMant = ((Uint32) (bytes[6] & 0xFF) << 24)
    | ((Uint32) (bytes[7] & 0xFF) << 16)
    | ((Uint32) (bytes[8] & 0xFF) << 8)
    | ((Uint32) (bytes[9] & 0xFF));

    if (expon == 0 && hiMant == 0 && loMant == 0) f = 0;
    else if (expon == 0x7FFF) f = HUGE_INT32;
    else {
    expon -= 16382;
    expon = 32-expon;
    if (expon < 0) f = HUGE_INT32;
    else f = hiMant >> expon;
    }

    if (bytes[0] & 0x80)
    return -f;
    else
    return f;
}

/*使用“gcc-o playaiff playaiff.c-lao-ldl-lm”编译*/
#包括
#包括
#包括
#包括
#包括
#定义MAXCHAN 8
ao_装置*装置；
ao_样本_格式；
#定义gshort（b）（（int）（（b）[0]）