怎样缩短DM365 音频 AD 直接DA的延时

zhenhai yuan

Prodigy 81 points

平台环境：

DM365 linux-2.6.32

AD/DA 芯片： AIC3104

用示波器测试，声音从Sound_read 直接到 Sound_write 的延时，发现在该延时与Sound_Attrs.bufSize 和给它们的Buffer_Handle 有关。

Sound_Attrs.bufSize 越小，Buffer_Handle 越小， AD到DA的延时就越小。

鉴于我采集到的声音还要通过无线网络传输，Buffer_Handle的最小值能设为576。当我把bufSize 都设为1时，此时的延时还有30多ms 。

为毛延时还这么大呢？？ AD直接DA的呀，困扰很久了！

测试程序如下：

12 年多前

0 zhenhai yuan 12 年多前

Prodigy 81 points

const Sound_Attrs Sound_Attrs_MONO_48_2048 = {

48000,

100,

Sound_Mode_FULLDUPLEX,

Sound_Input_MIC,

Sound_Std_ALSA,

2048,

};

#define AUDIOBUFSIZE 576

int main (int argc, char* argv[])

{

Buffer_Attrs bAttrs = Buffer_Attrs_DEFAULT;

Sound_Attrs sAttrsIn = Sound_Attrs_MONO_48_2048;

Sound_Handle hSoundIn = NULL;

Buffer_Handle hInBuf = NULL;

Sound_Attrs sAttrsOut = Sound_Attrs_MONO_48_2048;

Sound_Handle hSoundOut = NULL;

Buffer_Handle hOutBuf = NULL;

Dmai_init();

hInBuf = Buffer_create(AUDIOBUFSIZE, &bAttrs);

if (hInBuf == NULL)

{

printf("Failed to allocate input buffer\n");

exit(0);

}

//sAttrsIn.sampleRate=24000;//48000;//32000;

printf("Insample %d\n",(int)sAttrsIn.sampleRate);

sAttrsIn.mode = Sound_Mode_INPUT;

sAttrsIn.bufSize = 32;

// sAttrsIn.soundStd = Sound_Std_OSS;

hSoundIn = Sound_create(&sAttrsIn);

if (hSoundIn == NULL)

{

printf("Failed to create input speech device\n");

exit(0);

}

hOutBuf = Buffer_create(AUDIOBUFSIZE, &bAttrs);

if (hOutBuf == NULL)

{

printf("Failed to allocate hOutBuf buffer\n");

exit(0);

}

//sAttrsIn.sampleRate=24000;//48000;//32000;

printf("Insample %d\n",(int)sAttrsIn.sampleRate);

sAttrsOut.mode = Sound_Mode_OUTPUT;

sAttrsOut.leftGain = 127;//VolumeMap[MyInfo.Volume];//0~127

sAttrsOut.rightGain = 127;//VolumeMap[MyInfo.Volume];//0~127

sAttrsOut.bufSize = 32;

// sAttrsOut.soundStd = Sound_Std_OSS;

hSoundOut = Sound_create(&sAttrsOut);

if (hSoundOut == NULL)

{

printf("Failed to create sAttrsOut speech device\n");

exit(0);

}

while (1)

{

printf("sound read\n");

if (Sound_read(hSoundIn, hInBuf) < 0)

{

printf("Failed to read audio buffer\n");

break;

}

memcpy(Buffer_getUserPtr(hOutBuf),Buffer_getUserPtr(hInBuf),Buffer_getNumBytesUsed(hInBuf));

Buffer_setNumBytesUsed(hOutBuf, Buffer_getNumBytesUsed(hInBuf));

printf("sound write %d\n",Buffer_getNumBytesUsed(hInBuf));

if (Sound_write(hSoundOut, hOutBuf) < 0)

{

printf("Failed to write audio buffer\n");

break;

}

return 0;

}

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怎样缩短DM365 音频 AD 直接DA的延时