Linux DSP plays audio file

#include <unistd.h>#include<fcntl.h>#include<sys/types.h>#include<sys/ioctl.h>#include<stdlib.h>#include<stdio.h>#include<linux/soundcard.h>/*The following three parameters are related to a specific file * cmd:file audio file * [file Pass.wav] =>> Pass.wav:RIFF (Little-endian) data, WAVE Audio, Microso FT PCM, + bit, mono 44100 Hz * 1. 16-bit * 2. Mono for the channel =1, stereo for stereo = 2 * 3. 44100HZ frequency This is what we all know, and the number of bits to capture or play audio for a second. */#defineRate 44100#defineSIZE 16#defineCHANNELS 1//1 for Mono, 2 for stereo/*/buffer * /unsignedCharBuff[rate * SIZE * CHANNELS/8];//The buff has exactly one second of audio in it.intMain () {intFD; intwavfd;/*a descriptor for a WAV file*/    intArg/*IOCTL Parameters*/    intRet/*return value*/    /*turn on the DSP audio device*/FD= Open ("/DEV/DSP", o_wronly); if(FD <0) {printf ("Open OF/DEV/DSP failed"); Exit (1); } wavfd= Open ("Pass.wav", o_rdonly); if(Wavfd <0) {printf ("Open of WAV failed");        Close (FD); Exit (1); }    /*Set bit*/Arg=SIZE; RET= IOCTL (FD, Sound_pcm_write_bits, &Arg); if(ret = =-1) perror ("sound_pcm_write_bits IOCTL failed"); if(Arg! =SIZE) perror ("Unable to set sample size"); /*Set Channels*/Arg=CHANNELS; RET= IOCTL (FD, Sound_pcm_write_channels, &Arg); if(ret = =-1) perror ("Sound_pcm_write_channels IOCTL failed"); if(Arg! =CHANNELS) perror ("Unable to set number of channels"); /*set up rate*/Arg=Rate ; RET= IOCTL (FD, Sound_pcm_write_rate, &Arg); if(ret = =-1) perror ("Sound_pcm_write_write IOCTL failed"); /*read the Buff-size content from the WAV file, and then write to/DEV/DSP until the end of the file*/ 　　 /*Q: Here I tried to play two times, do not know what the situation, if you have encountered please advise. */     while(ret = read (wavfd, Buff,sizeof(buff))) >0) {        //printf ("Read size =%d\n", ret);Write (FD, Buff,sizeof(Buff)); /*The following code is used to play back the contents of the buffer when changing the parameters of the playing file*/ret= IOCTL (FD, Sound_pcm_sync,0); if(ret = =-1) perror ("Sound_pcm_sync IOCTL failed");    } close (FD); Close (WAVFD);} The following is an encapsulated interface that can be used directly:voidPlay_audio (intRateintBitsintChannelsChar*filename) {    intFD; intwavfd;/*a descriptor for a WAV file*/    intArg/*IOCTL Arg*/    intRet/*return value*/unsignedCharBuff[rate * bits * channels/8];//The buff has exactly one second of audio in it.    /*Open Device*/FD= Open ("/DEV/DSP", o_wronly); if(FD <0) {printf ("Open OF/DEV/DSP failed"); Exit (1); } wavfd=open (filename, o_rdonly); if(Wavfd <0) {printf ("Open of WAV failed");        Close (FD); Exit (1); }    /*Set Bits*/Arg=bits; RET= IOCTL (FD, Sound_pcm_write_bits, &Arg); if(ret = =-1) perror ("sound_pcm_write_bits IOCTL failed"); if(Arg! =SIZE) perror ("Unable to set sample size"); /*Set Channels*/Arg=channels; RET= IOCTL (FD, Sound_pcm_write_channels, &Arg); if(ret = =-1) perror ("Sound_pcm_write_channels IOCTL failed"); if(Arg! =CHANNELS) perror ("Unable to set number of channels"); /*Set Rate*/Arg=Rate ; RET= IOCTL (FD, Sound_pcm_write_rate, &Arg); if(ret = =-1) perror ("Sound_pcm_write_write IOCTL failed"); /*read the Buff-size content from the WAV file, and then write to/DEV/DSP until the end of the file*/     while(ret = read (wavfd, Buff,sizeof(buff))) >0) {printf ("Read size =%d\n", ret); Write (fd, buff,sizeof(Buff)); /*The following code is used to play back the contents of the buffer when changing the parameters of the playing file*/ret= IOCTL (FD, Sound_pcm_sync,0); if(ret = =-1) perror ("Sound_pcm_sync IOCTL failed");    } close (FD); Close (wavfd);}

Linux DSP plays audio file