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avutil/eval: add linear interpolation helper

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This commit is contained in:
Paul B Mahol 2017-08-18 09:15:33 +02:00
parent e3a4afca07
commit 1146133df8
2 changed files with 12 additions and 1 deletions
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3
doc/utils.texi
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@ -864,6 +864,9 @@ Load the value of the internal variable with number
@var{var}, which was previously stored with st(@var{var}, @var{expr}).
The function returns the loaded value.
@item lerp(x, y, z)
Return linear interpolation between @var{x} and @var{y} by amount of @var{z}.
@item log(x)
Compute natural logarithm of @var{x}.

10
libavutil/eval.c
View File

@ -155,7 +155,7 @@ struct AVExpr {
e_pow, e_mul, e_div, e_add,
e_last, e_st, e_while, e_taylor, e_root, e_floor, e_ceil, e_trunc, e_round,
e_sqrt, e_not, e_random, e_hypot, e_gcd,
e_if, e_ifnot, e_print, e_bitand, e_bitor, e_between, e_clip, e_atan2
e_if, e_ifnot, e_print, e_bitand, e_bitor, e_between, e_clip, e_atan2, e_lerp,
} type;
double value; // is sign in other types
union {
@ -208,6 +208,12 @@ static double eval_expr(Parser *p, AVExpr *e)
return e->value * (d >= eval_expr(p, e->param[1]) &&
d <= eval_expr(p, e->param[2]));
}
case e_lerp: {
double v0 = eval_expr(p, e->param[0]);
double v1 = eval_expr(p, e->param[1]);
double f = eval_expr(p, e->param[2]);
return v0 + (v1 - v0) * f;
}
case e_print: {
double x = eval_expr(p, e->param[0]);
int level = e->param[1] ? av_clip(eval_expr(p, e->param[1]), INT_MIN, INT_MAX) : AV_LOG_INFO;
@ -456,6 +462,7 @@ static int parse_primary(AVExpr **e, Parser *p)
else if (strmatch(next, "between"))d->type = e_between;
else if (strmatch(next, "clip" )) d->type = e_clip;
else if (strmatch(next, "atan2" )) d->type = e_atan2;
else if (strmatch(next, "lerp" )) d->type = e_lerp;
else {
for (i=0; p->func1_names && p->func1_names[i]; i++) {
if (strmatch(next, p->func1_names[i])) {
@ -654,6 +661,7 @@ static int verify_expr(AVExpr *e)
&& (!e->param[2] || verify_expr(e->param[2]));
case e_between:
case e_clip:
case e_lerp:
return verify_expr(e->param[0]) &&
verify_expr(e->param[1]) &&
verify_expr(e->param[2]);