linux音频采集,Linux下的音频采集与回放

最新推荐文章于 2024-04-22 23:35:12 发布

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最新推荐文章于 2024-04-22 23:35:12 发布

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文章标签： linux音频采集

本文介绍了sndtools库，它包含用于操作Linux音频设备的函数，如打开、关闭设备、设置格式和通道。源码中展示了如何使用ioctl调用来设置声音设备的采样率和位深度，并提供了录音和播放功能。通过对OpenSnd、CloseSnd、SetFormat和SetChannel等函数的分析，揭示了Linux音频编程的基本原理。

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以下假设你对ioctl已有一定的认识及了解

sndtools.h

代码:

#ifndef SNDTOOLS_H

#define SNDTOOLS_H

#include

#define FMT8BITS AFMT_S8_LE

#define FMT16BITS AFMT_S16_LE

#define FMT8K 8000

#define FMT16K 16000

#define FMT22K 22000

#define FMT44K 44000

#define MONO 1

#define STERO 2

#ifndef VAR_STATIC

extern int devfd;

extern int CapMask;

#endif //ifndef VAR_STATIC

//Open sound device, return 1 if open sUCcess

//else return 0

int OpenSnd();

//Close sound device

int CloseSnd();

//Set record or playback format, return 1 if success

//else return 0

int SetFormat(int bits, int hz);

//Set record or playback channel, return 1 if success

//else return 1

int SetChannel(int chn);

//Record

int Record(char *buf, int size);

//Playback

int Play(char *buf, int size);

#endif //ifndef SNDTOOLS_H

sndtools.c

代码:

#include

#define VAR_STATIC

#include "sndtools.h"

int devfd = 0;

* Open Sound device

* Return 1 if success, else return 0.

int OpenSnd(/* add by new version */int nWhich)

{

if(devfd > 0)

close(devfd);

devfd = open("/dev/dsp", O_RDWR);

if(devfd < 0)

return 0;

return 1;

}

* Close Sound device

* return 1 if success, else return 0.

int CloseSnd(/* add by new version */int nWhich)

{

close(devfd);

devfd = 0;

return 1;

}

* Set Record an Playback format

* return 1 if success, else return 0.

* bits -- FMT8BITS(8bits), FMT16BITS(16bits)

* hz -- FMT8K(8000HZ), FMT16K(16000HZ), FMT22K(22000HZ), FMT44K(44000HZ)

int SetFormat(int bits, int hz)

{

int tmp = bits;

if( -1 == ioctl(devfd, SNDCTL_DSP_SETFMT, &tmp))

{

#ifdef DEBUG_WARN

printf("Set fmt to s16_little faile:%d//n", nWhich);

#endif

return 0;

}

tmp = hz;

if( -1 == ioctl(devfd, SNDCTL_DSP_SPEED, &tmp))

{

#ifdef DEBUG_WARN

printf("Set speed to %d:%d//n", hz, nWhich);

#endif

return 0;

}

return 1;

}

* Set Sound Card Channel

* return 1 if success, else return 0.

* chn -- MONO, STERO

int SetChannel(int chn)

{

int tmp = chn;

if(-1 == ioctl(devfd, SNDCTL_DSP_CHANNELS, &tmp))

{

#ifdef DEBUG_WARN

printf("Set Audio Channel faile:%d//n", nWhich);

#endif

return 0;

}

return 1;

}

* Record

* return numbers of byte for read.

int Record(char *buf, int size)

{

return read(devfd, buf, size);

}

* Playback

* return numbers of byte for write.

int Play(char *buf, int size)

{

return write(devfd, buf, size);

}