static int libdax_audioxtr_identify_au(struct libdax_audioxtr *o, int flag)
{
int ret,encoding;
char buf[24];
/* Check wether this is a Sun Audio, .au file */
/* info used: http://ccrma.stanford.edu/courses/422/projects/WaveFormat/ */
if(o->fd!=0) {
ret= lseek(o->fd,0,SEEK_SET);
if(ret==-1)
return(0);
}
ret= read(o->fd, buf, 24);
if(ret<24)
return(0);
if(strncmp(buf,".snd",4)!=0)
return(0);
strcpy(o->fmt,".au");
o->msb_first= 1;
o->au_data_location= libdax_audioxtr_to_int(o,(unsigned char *)buf+4,4,1);
o->au_data_size= libdax_audioxtr_to_int(o,(unsigned char *)buf+8,4,1);
encoding= libdax_audioxtr_to_int(o,(unsigned char *)buf+12,4,1);
if(encoding==2)
o->bits_per_sample= 8;
else if(encoding==3)
o->bits_per_sample= 16;
else if(encoding==4)
o->bits_per_sample= 24;
else if(encoding==5)
o->bits_per_sample= 32;
else
o->bits_per_sample= -encoding;
o->sample_rate= libdax_audioxtr_to_int(o,(unsigned char *)buf+16,4,1);
o->num_channels= libdax_audioxtr_to_int(o,(unsigned char *)buf+20,4,1);
if(o->au_data_size!=0xffffffff)
o->data_size= o->au_data_size;
else
o->data_size= 0;
sprintf(o->fmt_info,
".au , num_channels=%d , sample_rate=%d , bits_per_sample=%d",
o->num_channels,o->sample_rate,o->bits_per_sample);
/* <<< for testing only */;
return(1);
return(o->bits_per_sample>0); /* Audio format must be linear PCM */
}
static int libdax_audioxtr_identify_wav(struct libdax_audioxtr *o, int flag)
{
int ret;
char buf[45];
/* check wether this is a MS WAVE file .wav */
/* info used: http://ccrma.stanford.edu/courses/422/projects/WaveFormat/ */
if(o->fd!=0) {
ret= lseek(o->fd,0,SEEK_SET);
if(ret==-1)
return(0);
}
ret= read(o->fd, buf, 44);
if(ret<44)
return(0);
buf[44]= 0; /* as stopper for any string operations */
if(strncmp(buf,"RIFF",4)!=0) /* ChunkID */
return(0);
if(strncmp(buf+8,"WAVE",4)!=0) /* Format */
return(0);
if(strncmp(buf+12,"fmt ",4)!=0) /* Subchunk1ID */
return(0);
if(buf[16]!=16 || buf[17]!=0 || buf[18]!=0 || buf[19]!=0) /* Subchunk1Size */
return(0);
if(buf[20]!=1 || buf[21]!=0) /* AudioFormat must be 1 (Linear quantization) */
return(0);
strcpy(o->fmt,".wav");
o->msb_first= 0;
o->num_channels= libdax_audioxtr_to_int(o,(unsigned char *) buf+22,2,0);
o->sample_rate= libdax_audioxtr_to_int(o,(unsigned char *) buf+24,4,0);
o->bits_per_sample= libdax_audioxtr_to_int(o,(unsigned char *)buf+34,2,0);
sprintf(o->fmt_info,
".wav , num_channels=%d , sample_rate=%d , bits_per_sample=%d",
o->num_channels,o->sample_rate,o->bits_per_sample);
o->wav_subchunk2_size= libdax_audioxtr_to_int(o,(unsigned char *)buf+40,4,0);
o->data_size= o->wav_subchunk2_size;
return(1);
}
