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Code Issues Releases Activity

eval: treat dB as decibels instead of decibytes

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This commit is contained in:
Justin Ruggles 2012-09-28 16:36:58 -04:00
parent ac7eb4cb20
commit 5312268b34
2 changed files with 30 additions and 3 deletions
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27
libavutil/eval.c
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@ -81,7 +81,11 @@ double av_strtod(const char *numstr, char **tail)
d = strtod(numstr, &next);
/* if parsing succeeded, check for and interpret postfixes */
if (next!=numstr) {
if (*next >= 'E' && *next <= 'z') {
if (next[0] == 'd' && next[1] == 'B') {
/* treat dB as decibels instead of decibytes */
d = pow(10, d / 20);
next += 2;
} else if (*next >= 'E' && *next <= 'z') {
int e= si_prefixes[*next - 'E'];
if (e) {
if (next[1] == 'i') {
@ -339,16 +343,31 @@ static int parse_pow(AVExpr **e, Parser *p, int *sign)
return parse_primary(e, p);
}
static int parse_dB(AVExpr **e, Parser *p, int *sign)
{
/* do not filter out the negative sign when parsing a dB value.
for example, -3dB is not the same as -(3dB) */
if (*p->s == '-') {
char *next;
strtod(p->s, &next);
if (next != p->s && next[0] == 'd' && next[1] == 'B') {
*sign = 0;
return parse_primary(e, p);
}
}
return parse_pow(e, p, sign);
}
static int parse_factor(AVExpr **e, Parser *p)
{
int sign, sign2, ret;
AVExpr *e0, *e1, *e2;
if ((ret = parse_pow(&e0, p, &sign)) < 0)
if ((ret = parse_dB(&e0, p, &sign)) < 0)
return ret;
while(p->s[0]=='^'){
e1 = e0;
p->s++;
if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
if ((ret = parse_dB(&e2, p, &sign2)) < 0) {
av_expr_free(e1);
return ret;
}
@ -629,6 +648,8 @@ int main(int argc, char **argv)
"not(1)",
"not(NAN)",
"not(0)",
"6.0206dB",
"-3.0103dB",
NULL
};

6
tests/ref/fate/eval
View File

@ -184,5 +184,11 @@ Evaluating 'not(NAN)'
Evaluating 'not(0)'
'not(0)' -> 1.000000
Evaluating '6.0206dB'
'6.0206dB' -> 2.000000
Evaluating '-3.0103dB'
'-3.0103dB' -> 0.707107
12.700000 == 12.7
0.931323 == 0.931322575