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avfilter/scale: add function to check expressions 

Allows finer identification and logging of invalid expressions and use
of a single list for symbols and their index for both scale and
scale2ref.
This commit is contained in:
Gyan Doshi 2019-12-31 17:15:01 +05:30
parent 6310fbd543
commit ce2cfa67aa
1 changed files with 67 additions and 46 deletions
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113
libavfilter/vf_scale.c
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@ -54,6 +54,13 @@ static const char *const var_names[] = {
"vsub",
"ohsub",
"ovsub",
"main_w",
"main_h",
"main_a",
"main_sar",
"main_dar", "mdar",
"main_hsub",
"main_vsub",
NULL
};
@ -69,39 +76,6 @@ enum var_name {
VAR_VSUB,
VAR_OHSUB,
VAR_OVSUB,
VARS_NB
};
/**
* This must be kept in sync with var_names so that it is always a
* complete list of var_names with the scale2ref specific names
* appended. scale2ref values must appear in the order they appear
* in the var_name_scale2ref enum but also be below all of the
* non-scale2ref specific values.
*/
static const char *const var_names_scale2ref[] = {
"in_w", "iw",
"in_h", "ih",
"out_w", "ow",
"out_h", "oh",
"a",
"sar",
"dar",
"hsub",
"vsub",
"ohsub",
"ovsub",
"main_w",
"main_h",
"main_a",
"main_sar",
"main_dar", "mdar",
"main_hsub",
"main_vsub",
NULL
};
enum var_name_scale2ref {
VAR_S2R_MAIN_W,
VAR_S2R_MAIN_H,
VAR_S2R_MAIN_A,
@ -109,7 +83,7 @@ enum var_name_scale2ref {
VAR_S2R_MAIN_DAR, VAR_S2R_MDAR,
VAR_S2R_MAIN_HSUB,
VAR_S2R_MAIN_VSUB,
VARS_S2R_NB
VARS_NB
};
enum EvalMode {
@ -145,7 +119,7 @@ typedef struct ScaleContext {
char *h_expr; ///< height expression string
AVExpr *w_pexpr;
AVExpr *h_pexpr;
double var_values[VARS_NB + VARS_S2R_NB];
double var_values[VARS_NB];
char *flags_str;
@ -173,14 +147,57 @@ AVFilter ff_vf_scale2ref;
static int config_props(AVFilterLink *outlink);
static int check_exprs(AVFilterContext *ctx)
{
ScaleContext *scale = ctx->priv;
unsigned vars_w[VARS_NB] = { 0 }, vars_h[VARS_NB] = { 0 };
if (!scale->w_pexpr && !scale->h_pexpr)
return AVERROR(EINVAL);
if (scale->w_pexpr)
av_expr_count_vars(scale->w_pexpr, vars_w, VARS_NB);
if (scale->h_pexpr)
av_expr_count_vars(scale->h_pexpr, vars_h, VARS_NB);
if (vars_w[VAR_OUT_W] || vars_w[VAR_OW]) {
av_log(ctx, AV_LOG_ERROR, "Width expression cannot be self-referencing: '%s'.\n", scale->w_expr);
return AVERROR(EINVAL);
}
if (vars_h[VAR_OUT_H] || vars_h[VAR_OH]) {
av_log(ctx, AV_LOG_ERROR, "Height expression cannot be self-referencing: '%s'.\n", scale->h_expr);
return AVERROR(EINVAL);
}
if ((vars_w[VAR_OUT_H] || vars_w[VAR_OH]) &&
(vars_h[VAR_OUT_W] || vars_h[VAR_OW])) {
av_log(ctx, AV_LOG_ERROR, "Circular expressions invalid for width '%s' and height '%s'.\n", scale->w_expr, scale->h_expr);
return AVERROR(EINVAL);
}
if (ctx->filter != &ff_vf_scale2ref &&
(vars_w[VAR_S2R_MAIN_W] || vars_h[VAR_S2R_MAIN_W] ||
vars_w[VAR_S2R_MAIN_H] || vars_h[VAR_S2R_MAIN_H] ||
vars_w[VAR_S2R_MAIN_A] || vars_h[VAR_S2R_MAIN_A] ||
vars_w[VAR_S2R_MAIN_SAR] || vars_h[VAR_S2R_MAIN_SAR] ||
vars_w[VAR_S2R_MAIN_DAR] || vars_h[VAR_S2R_MAIN_DAR] ||
vars_w[VAR_S2R_MDAR] || vars_h[VAR_S2R_MDAR] ||
vars_w[VAR_S2R_MAIN_HSUB] || vars_h[VAR_S2R_MAIN_HSUB] ||
vars_w[VAR_S2R_MAIN_VSUB] || vars_h[VAR_S2R_MAIN_VSUB]) ) {
av_log(ctx, AV_LOG_ERROR, "Expressions with scale2ref variables are not valid in scale filter.\n");
return AVERROR(EINVAL);
}
return 0;
}
static int scale_parse_expr(AVFilterContext *ctx, char *str_expr, AVExpr **pexpr_ptr, const char *var, const char *args)
{
ScaleContext *scale = ctx->priv;
int ret, is_inited = 0;
char *old_str_expr = NULL;
AVExpr *old_pexpr = NULL;
const char scale2ref = ctx->filter == &ff_vf_scale2ref;
const char *const *names = scale2ref ? var_names_scale2ref : var_names;
if (str_expr) {
old_str_expr = av_strdup(str_expr);
@ -195,13 +212,17 @@ static int scale_parse_expr(AVFilterContext *ctx, char *str_expr, AVExpr **pexpr
is_inited = 1;
}
ret = av_expr_parse(pexpr_ptr, args, names,
ret = av_expr_parse(pexpr_ptr, args, var_names,
NULL, NULL, NULL, NULL, 0, ctx);
if (ret < 0) {
av_log(ctx, AV_LOG_ERROR, "Cannot parse expression for %s: '%s'\n", var, args);
goto revert;
}
ret = check_exprs(ctx);
if (ret < 0)
goto revert;
if (is_inited && (ret = config_props(ctx->outputs[0])) < 0)
goto revert;
@ -391,15 +412,15 @@ static int scale_eval_dimensions(AVFilterContext *ctx)
scale->var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
if (scale2ref) {
scale->var_values[VARS_NB + VAR_S2R_MAIN_W] = main_link->w;
scale->var_values[VARS_NB + VAR_S2R_MAIN_H] = main_link->h;
scale->var_values[VARS_NB + VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
scale->var_values[VARS_NB + VAR_S2R_MAIN_SAR] = main_link->sample_aspect_ratio.num ?
scale->var_values[VAR_S2R_MAIN_W] = main_link->w;
scale->var_values[VAR_S2R_MAIN_H] = main_link->h;
scale->var_values[VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
scale->var_values[VAR_S2R_MAIN_SAR] = main_link->sample_aspect_ratio.num ?
(double) main_link->sample_aspect_ratio.num / main_link->sample_aspect_ratio.den : 1;
scale->var_values[VARS_NB + VAR_S2R_MAIN_DAR] = scale->var_values[VARS_NB + VAR_S2R_MDAR] =
scale->var_values[VARS_NB + VAR_S2R_MAIN_A] * scale->var_values[VARS_NB + VAR_S2R_MAIN_SAR];
scale->var_values[VARS_NB + VAR_S2R_MAIN_HSUB] = 1 << main_desc->log2_chroma_w;
scale->var_values[VARS_NB + VAR_S2R_MAIN_VSUB] = 1 << main_desc->log2_chroma_h;
scale->var_values[VAR_S2R_MAIN_DAR] = scale->var_values[VAR_S2R_MDAR] =
scale->var_values[VAR_S2R_MAIN_A] * scale->var_values[VAR_S2R_MAIN_SAR];
scale->var_values[VAR_S2R_MAIN_HSUB] = 1 << main_desc->log2_chroma_w;
scale->var_values[VAR_S2R_MAIN_VSUB] = 1 << main_desc->log2_chroma_h;
}
res = av_expr_eval(scale->w_pexpr, scale->var_values, NULL);