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add covenience functions parsing gains/peaks from vorbis comments and computing the scale factor from the gain

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Josh Coalson
2002-11-05 07:25:36 +00:00
parent b667e70b82
commit a3963a6d9c
2 changed files with 66 additions and 0 deletions
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63
src/share/replaygain/replaygain.c
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@@ -22,6 +22,7 @@
#include "FLAC/assert.h"
#include "FLAC/file_decoder.h"
#include "FLAC/metadata.h"
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -541,3 +542,65 @@ REPLAYGAIN_API const char *FLAC__replaygain_store_to_file_title(const char *file
return 0;
}
static FLAC__bool parse_double_(const FLAC__StreamMetadata_VorbisComment_Entry *entry, double *val)
{
char s[32], *end;
const char *p, *q;
double v;
FLAC__ASSERT(0 != entry);
FLAC__ASSERT(0 != val);
fprintf(stderr,"@@@@ tag=[");fwrite(entry->entry,1,entry->length,stderr);fprintf(stderr,"]\n");
p = (const char *)entry->entry;
q = strchr(p, '=');
if(0 == q)
return false;
q++;
memset(s, 0, sizeof(s)-1);
strncpy(s, q, local_min(sizeof(s)-1, entry->length - (q-p)));
fprintf(stderr,"@@@@ s=[%s]\n",s);
v = strtod(s, &end);
if(end == s)
return false;
*val = v;
fprintf(stderr,"@@@@ v=[%0.12f]\n",v);
return true;
}
REPLAYGAIN_API FLAC__bool FLAC__replaygain_load_from_vorbiscomment(const FLAC__StreamMetadata *block, FLAC__bool album_mode, double *gain, double *peak)
{
int gain_offset, peak_offset;
FLAC__ASSERT(0 != block);
FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
if(0 > (gain_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, album_mode? tag_album_gain_ : tag_title_gain_)))
return false;
if(0 > (peak_offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, /*offset=*/0, album_mode? tag_album_peak_ : tag_title_peak_)))
return false;
if(!parse_double_(block->data.vorbis_comment.comments + gain_offset, gain))
return false;
if(!parse_double_(block->data.vorbis_comment.comments + peak_offset, peak))
return false;
return true;
}
REPLAYGAIN_API double FLAC__replaygain_compute_scale_factor(double peak, double gain, double preamp, FLAC__bool prevent_clipping)
{
double scale;
FLAC__ASSERT(peak >= 0.0);
gain += preamp;
scale = (float) pow(10.0, gain * 0.05);
if(prevent_clipping && peak > 0.0) {
const double max_scale = (float)(1.0 / peak);
if(scale > max_scale)
scale = max_scale;
}
return scale;
}