/* * playsnd.oss -- replacement for playsnd.m for Linux using OSS API * Copyright (c) 1997 Kristopher D. Giesing */ /* * Based on Open Sound System specifications * Reference: see Open Sound System Programmer's Guide on WWW at * http://www.opensound.com/pguide/index.html */ /* Includes: */ #include #include #include /* Needed for signal() */ #include /* Needed for memcpy() */ #include #include /* needed for open() */ #include /* OSS Audio functions */ #include "mex.h" /* Needed for MATLAB gateway functions */ #define NORMALLY 0 static int audio_fd; static void (*mwCtrlC)(int); void expire( char *message /* Error message; NULL is normal exit */ ) { signal(SIGINT, mwCtrlC); if (audio_fd != 0) { if (close(audio_fd) == -1) { mexErrMsgTxt("Unable to close /dev/dsp"); } else { if (message != NORMALLY) { mexErrMsgTxt(message); } } } return; } void sndCtrlC(int input) { expire("Interrupted."); } int sndInitDevice(char *device) { /* Leave gracefully if this machine has no audio capabilities */ if ((audio_fd = open(device, O_WRONLY, 0)) == -1) mexErrMsgTxt("Could not open audio device"); /* * Now that we've opened the file, we need to swap in our * own signal handler */ mwCtrlC = signal(SIGINT, sndCtrlC); return; } int sndGetStereoMode(int ncols, double **pdata, int *pnum_samples) { int stereo = 0; if (ncols == 2) { stereo = 1; if (ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo)==-1) expire("Unable to query /dev/dsp"); if (stereo != 1) { mexWarnMsgTxt("Device does not support stereo sound; using mono"); *pnum_samples = (*pnum_samples)/2; /* Drop last half of signal */ } } else { if (ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo) == -1) expire("Unable to query /dev/dsp"); if (stereo != 0) { double *temp; mexWarnMsgTxt("Device does not support mono sound."); /* * Attempt to simulate mono by duplicating the signal */ temp = mxMalloc((*pnum_samples)*2*sizeof(double)); memcpy(temp, *pdata, (*pnum_samples)*sizeof(double)); memcpy(temp+*pnum_samples, *pdata, *pnum_samples*sizeof(double)); *pdata = temp; *pnum_samples = (*pnum_samples)*2; } } return(stereo); } int sndGetFormat( int bits ) { int format; if (ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &format) == -1) expire("Unable to query /dev/dsp"); if ((format & AFMT_S16_LE) && (bits == 0 || bits == 16)) { format = AFMT_S16_LE; } else if ((format & AFMT_U16_LE) && (bits == 0 || bits == 16)) { format = AFMT_U16_LE; } else if ((format & AFMT_U8) && (bits == 0 || bits == 8)) { format = AFMT_U8; } else if ((format & AFMT_S8) && (bits == 0 || bits == 8)) { format = AFMT_S8; } else { expire("Unable to find a suitable audio format"); } return(format); } unsigned char *sndConvertData( double *data, int num_samples, int format, int stereo, int *buffer_size ) { int rcoffset = num_samples/2; /* Start of right channel data */ int ssize; /* Sample size in bytes */ int scale; /* Scale to max. dynamic range */ int offset; /* Offset for unsigned data */ unsigned char *devbuf; int i,p,datum; switch (format) { case AFMT_S16_LE: ssize = 2; scale = 32767; offset = 0; break; case AFMT_U16_LE: ssize = 2; scale = 32767; offset = 32768; break; case AFMT_U8: ssize = 1; scale = 127; offset = 128; break; case AFMT_S8: ssize = 1; scale = 127; offset = 0; break; } *buffer_size = num_samples*ssize*sizeof(char); devbuf = mxMalloc(*buffer_size); if (ssize == 1) { /* Eight bit data */ for (i=0,p=0;p<*buffer_size;i++) { devbuf[p++] = (unsigned char)(data[i]*127 + offset); if (stereo) { devbuf[p++] = (unsigned char)(data[rcoffset+i]*127 + offset); } } } else { /* Sixteen bit data */ for (i=0,p=0;p<*buffer_size;i++) { datum = (int)(data[i]*scale + offset); /* first send the low byte then the high byte */ devbuf[p++] = (unsigned char)( datum & 0xff); devbuf[p++] = (unsigned char)((datum >> 8) & 0xff); if (stereo) { datum = (int)(data[rcoffset+i]*scale + offset); /* first send the low byte then the high byte */ devbuf[p++] = (unsigned char)( datum & 0xff); devbuf[p++] = (unsigned char)((datum >> 8) & 0xff); } } } return(devbuf); } void sndPlay( double *data, int num_samples, int sampling_rate, int stereo, int bits ) { int format; unsigned char *devbuf; int i, datum, len, bufsize, p=0; format = sndGetFormat(bits); /* Set sample format */ if (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &format)==-1) expire("Error writing format to /dev/dsp"); /* Convert audio data */ devbuf = sndConvertData(data, num_samples, format, stereo, &bufsize); /* Set sample rate */ if (ioctl(audio_fd,SNDCTL_DSP_SPEED, &sampling_rate)==-1) expire("Error writing format to /dev/dsp"); /* Write to output device */ if ((len = write(audio_fd, devbuf, bufsize)) == -1) expire("Error writing data to /dev/dsp"); } void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] ) { double *data; int num_samples, sample_rate, stereo, bits; audio_fd = 0; /* * This function returns no outputs */ if (nlhs != 0) mexErrMsgTxt("Too many output arguments"); /* Check input arguments */ switch (nrhs) { case 0: /* * This return here takes us back to matlab prompt. The reason * why we do this is because playsnd with no args on sun returns * silently without playing anything */ return; break; case 1: sample_rate = 8192; /* Use 8192 Hz by default */ bits = 0; /* determine best sample resolution */ break; case 2: sample_rate = (int)mxGetScalar(prhs[1]); bits = 0; /* determine best sample resolution */ break; case 3: sample_rate = (int)mxGetScalar(prhs[1]); bits = (int)mxGetScalar(prhs[2]); break; default: expire("Too many input arguments."); break; } sndInitDevice("/dev/dsp"); num_samples = mxGetM(prhs[0])*mxGetN(prhs[0]); stereo = sndGetStereoMode(mxGetN(prhs[0]), &data, &num_samples); data = mxGetPr(prhs[0]); sndPlay(data, num_samples, sample_rate, stereo, bits); /* * Exit normallly */ expire(NORMALLY); return; }