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Adapting to surplus chunks and subchunks in .wav files

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This commit is contained in:
Thomas Schmitt
2017-12-31 12:15:36 +01:00
parent b5b5cc1fb2
commit ef2fa1d99d
3 changed files with 192 additions and 31 deletions
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137
libburn/libdax_audioxtr.c
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@ -55,6 +55,7 @@ int libdax_audioxtr_new(struct libdax_audioxtr **xtr, char *path, int flag)
o->bits_per_sample= 0;
o->msb_first= 0;
o->wav_data_location= 44;
o->wav_subchunk2_size= 0;
o->au_data_location= 0;
@ -121,47 +122,123 @@ static int libdax_audioxtr_open(struct libdax_audioxtr *o, int flag)
return(1);
}
/* @param flag: bit0= sequential file, skip by reading data
*/
static int libdax_audioxtr_skip(struct libdax_audioxtr *o,
off_t *old_pos,
off_t pos, int flag)
{
int ret;
size_t to_read;
static char buf[256]; /* Thread safe because the content does not matter */
if((flag & 1) || o->fd == 0) { /* stdin */
while(pos - *old_pos > 0) {
to_read= pos - *old_pos;
if(to_read > sizeof(buf))
to_read= sizeof(buf);
ret= read(o->fd, buf, to_read);
if(ret < (int) to_read)
return(0);
*old_pos+= to_read;
}
} else {
ret= lseek(o->fd, pos, SEEK_SET);
if(ret == -1)
return(0);
*old_pos= pos;
}
return(1);
}
static int libdax_audioxtr_identify_wav(struct libdax_audioxtr *o, int flag)
{
int ret;
char buf[45];
int ret, fmt_seen= 0, data_seen= 0;
off_t pos= 0, old_pos= 0, riff_end= 0;
char buf[16];
unsigned char *ubuf;
/* check wether this is a MS WAVE file .wav */
/* info used: http://ccrma.stanford.edu/courses/422/projects/WaveFormat/ */
/* info used: http://ccrma.stanford.edu/courses/422/projects/WaveFormat/
https://en.wikipedia.org/wiki/WAV
see summary in: doc/waveformat.txt
*/
ubuf= (unsigned char *) buf;
if(o->fd!=0) {
ret= lseek(o->fd,0,SEEK_SET);
if(ret==-1)
/* Look for ChunkID "RIFF" , tolerate other known chunks */
while(1) {
ret= libdax_audioxtr_skip(o, &old_pos, pos, 0);
if(ret <= 0)
return(0);
ret= read(o->fd, buf, 8);
if(ret < 8)
return(0);
old_pos+= 8;
pos= old_pos + libdax_audioxtr_to_int(o, ubuf + 4, 4, 0);
if(pos > 0xffffffff || pos - old_pos < 4) /* Too large or no Format word */
return(0);
if(strncmp(buf, "RIFF", 4) == 0)
break;
/* Wikipedia mentions these known ChunkId values */
if(strncmp(buf, "INFO", 4) == 0 ||
strncmp(buf, "CSET", 4) == 0 ||
strncmp(buf, "JUNK", 4) == 0 ||
strncmp(buf, "PAD ", 4) == 0)
continue;
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 */
/* Read RIFF Format header */
ret= read(o->fd, buf, 4);
if(ret < 4)
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) */
old_pos+= 4;
if(strncmp(buf, "WAVE", 4) != 0) /* Format */
return(0);
riff_end= pos;
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);
/* Look for SubchunkID "fmt " and "data" */
pos= old_pos;
while(old_pos < riff_end) {
ret= libdax_audioxtr_skip(o, &old_pos, pos, 0);
if(ret <= 0)
return(0);
ret= read(o->fd, buf, 8);
if(ret < 8)
return(0);
old_pos= pos + 8;
pos= old_pos + libdax_audioxtr_to_int(o, ubuf + 4, 4, 0); /* SubchunkSize */
if(strncmp(buf,"fmt ", 4) == 0) {
if(pos - old_pos < 16)
return(0);
ret= read(o->fd, buf, 16);
if(ret < 16)
return(0);
old_pos+= 16;
if(buf[0]!=1 || buf[1]!=0) /* AudioFormat (1 = Linear quantization) */
return(0);
o->msb_first= 0;
o->num_channels= libdax_audioxtr_to_int(o, ubuf + 2 , 2, 0);
o->sample_rate= libdax_audioxtr_to_int(o, ubuf + 4, 4, 0);
o->bits_per_sample= libdax_audioxtr_to_int(o, ubuf + 14, 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);
fmt_seen= 1;
} else if(strncmp(buf,"data", 4) == 0) {
o->wav_data_location= old_pos;
o->wav_subchunk2_size= pos - old_pos;
o->data_size= o->wav_subchunk2_size;
data_seen= 1;
}
if(fmt_seen && data_seen) {
strcpy(o->fmt,".wav");
return(1);
}
}
return(0);
}
@ -256,7 +333,7 @@ static int libdax_audioxtr_init_reading(struct libdax_audioxtr *o, int flag)
o->extract_count= 0;
if(strcmp(o->fmt,".wav")==0)
ret= lseek(o->fd,44,SEEK_SET);
ret= lseek(o->fd, o->wav_data_location, SEEK_SET);
else if(strcmp(o->fmt,".au")==0)
ret= lseek(o->fd,o->au_data_location,SEEK_SET);
else