OSS音频接口写的录音播放小程序，在2440 上测试成功

hjj742975525 · 发表于 2013-9-14 10:55:42

前两天用OSS音频接口写的一个录音和播放小程序，播放的时候，声音比较小，但是如果大声一点录，放出来还能稍微大点，但还是比较小，什么原因？贴上代码：录音的：（按下板子上的key1开始录音，松开按键录音结束，录音存放在record.wav里面）

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/soundcard.h>
#define AUDIO_DEVICE "/dev/dsp"
#define RATE 48000
#define CHANNELS 2
#define SIZE 16
#define PAGE_SIZE 4096
#define RECORD_DIR "/tmp/"
#define KEY_DEVICE "/dev/IRQ-Test"
#define KEY_N 4
#define KEY1 0
int main (int argc, char *argv[])
{
int keyfd, dspfd;
char key_buf[KEY_N], record_buf[PAGE_SIZE];
int arg;
/*open dsp read only and init*/
dspfd = open (AUDIO_DEVICE, O_RDONLY);
if (-1 == dspfd) {
perror ("##open dsp erro");
exit (1);
}
/*set format*/
arg = SIZE;
if (-1 == ioctl (dspfd, SOUND_PCM_WRITE_BITS, &arg)) {
perror ("##set simple format erro");
goto out3;
}
/*set channels*/
arg = CHANNELS;
if (-1 == ioctl (dspfd, SOUND_PCM_WRITE_CHANNELS, &arg)) {
perror ("##set channels erro");
goto out3;
}
/*set speed*/
arg = RATE;
if (-1 == ioctl (dspfd, SOUND_PCM_WRITE_RATE, &arg)) {
perror ("##set speed erro");
goto out3;
}
/*create a file to store the record file*/
FILE *filep = fopen (RECORD_DIR"record.wav", "w");
if (NULL == filep) {
printf ("##open file to record erro\n");
goto out3;
}
/*open the key ,read only and nonblock*/
keyfd = open (KEY_DEVICE, O_RDONLY | O_NONBLOCK);
if (-1 == keyfd) {
perror ("##open key erro");
goto out2;
}
printf ("<press down the KEY1 to record> \n");
int record_end_flag = 1;
while (record_end_flag) {
if ((-1 == read (keyfd, key_buf, KEY_N)) && (EAGAIN != errno)) {
perror ("##read key vaule erro");
goto out1;
}
/*KEY1 down*/
while (key_buf[KEY1] != '0') {
if ((-1 == read (keyfd, key_buf, KEY_N)) && (EAGAIN != errno)) {
perror ("##read key vaule erro");
goto out1;
}
/*key down*/
int num = read (dspfd, record_buf, PAGE_SIZE);
int write_n = fwrite (record_buf, sizeof (char), num, filep);
if (write_n < num) {
printf ("##write to the record file erro\n");
goto out1;
}
/*key up, record end*/
if (key_buf[KEY1] == '0') {
record_end_flag = 0;
printf ("<record end>\n");
}
}
}
out1:
close (keyfd);
out2:
fclose (filep);
out3:
close (dspfd);
return 0;
}

复制代码

播放的：（播放录音record.wav）

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/soundcard.h>
#define AUDIO_DEVICE "/dev/dsp"
#define RATE 48000
#define CHANNELS 2
#define SIZE 16
#define PAGE_SIZE 4096
#define VOLUME 100 //max
int main (int argc, char *argv[])
{
int dspfd;
char record_buf[PAGE_SIZE];
int arg;
if (argc < 2){
printf ("Usage: ./playrec filename\n");
exit (1);
}
/*open dsp write only and init*/
dspfd = open (AUDIO_DEVICE, O_WRONLY);
if (-1 == dspfd) {
perror ("##open dsp erro");
exit (1);
}
/*set format*/
arg = SIZE;
if (-1 == ioctl (dspfd, SOUND_PCM_WRITE_BITS, &arg)) {
perror ("##set simple format erro");
goto out1;
}
/*set channels*/
arg = CHANNELS;
if (-1 == ioctl (dspfd, SOUND_PCM_WRITE_CHANNELS, &arg)) {
perror ("##set channels erro");
goto out1;
}
/*set speed*/
arg = RATE;
if (-1 == ioctl (dspfd, SOUND_PCM_WRITE_RATE, &arg)) {
perror ("##set speed erro");
goto out1;
}
/*set the volume*/
arg = (VOLUME << 8) | VOLUME;
if (-1 == ioctl (dspfd, SOUND_MIXER_WRITE_VOLUME, &arg)) {
perror ("##set volume erro");
goto out1;
}
/*open the record file*/
FILE *filep = fopen (argv[1], "r");
if (NULL == filep) {
printf ("##open the record file erro\n");
goto out1;
}
/*play the record*/
int num;
while ((num = fread (record_buf, sizeof (char), PAGE_SIZE, filep)) > 0) {
if (-1 == write (dspfd, record_buf, num)) {
perror ("##write dsp erro");
goto out2;
}
}
out2:
fclose (filep);
out1:
close (dspfd);
return 0;
}

复制代码

亚瑟王 · 发表于 2013-9-16 10:00:48

这个和声卡的通道有关系，我们引出来的通道是line-in通道，应该用mic通道。硬件上需要修改一下，同时软件驱动也需要对应的修改，声音就大了。

(^_^)∠※※ · 发表于 2013-12-12 13:29:03

怎么修改声音会变大啊

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OSS音频接口写的录音播放小程序，在2440 上测试成功

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