---
libavutil/eval.c | 25 ++++++++++++++++++++++---
1 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/libavutil/eval.c b/libavutil/eval.c
index 9d17930..aad4015 100644
--- a/libavutil/eval.c
+++ b/libavutil/eval.c
@@ -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;
}
--
1.7.1
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