Scale (resize) the input video, based on a reference video.
See the scale filter for available options, scale2ref supports the same but
-uses the reference video instead of the main input as basis.
+uses the reference video instead of the main input as basis. scale2ref also
+supports the following additional constants for the @option{w} and
+@option{h} options:
+
+@table @var
+@item main_w
+@item main_h
+The main input video's width and height
+
+@item main_a
+The same as @var{main_w} / @var{main_h}
+
+@item main_sar
+The main input video's sample aspect ratio
+
+@item main_dar, mdar
+The main input video's display aspect ratio. Calculated from
+@code{(main_w / main_h) * main_sar}.
+
+@item main_hsub
+@item main_vsub
+The main input video's horizontal and vertical chroma subsample values.
+For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub}
+is 1.
+@end table
@subsection Examples
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[] = {
+ "PI",
+ "PHI",
+ "E",
+ "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,
+ VAR_S2R_MAIN_SAR,
+ VAR_S2R_MAIN_DAR, VAR_S2R_MDAR,
+ VAR_S2R_MAIN_HSUB,
+ VAR_S2R_MAIN_VSUB,
+ VARS_S2R_NB
+};
+
int ff_scale_eval_dimensions(void *log_ctx,
const char *w_expr, const char *h_expr,
AVFilterLink *inlink, AVFilterLink *outlink,
int factor_w, factor_h;
int eval_w, eval_h;
int ret;
- double var_values[VARS_NB], res;
+ const char scale2ref = outlink->src->inputs[1] == inlink;
+ double var_values[VARS_NB + VARS_S2R_NB], res;
+ const AVPixFmtDescriptor *main_desc;
+ const AVFilterLink *main_link;
+ const char *const *names = scale2ref ? var_names_scale2ref : var_names;
+
+ if (scale2ref) {
+ main_link = outlink->src->inputs[0];
+ main_desc = av_pix_fmt_desc_get(main_link->format);
+ }
var_values[VAR_PI] = M_PI;
var_values[VAR_PHI] = M_PHI;
var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w;
var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
+ if (scale2ref) {
+ var_values[VARS_NB + VAR_S2R_MAIN_W] = main_link->w;
+ var_values[VARS_NB + VAR_S2R_MAIN_H] = main_link->h;
+ var_values[VARS_NB + VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
+ var_values[VARS_NB + VAR_S2R_MAIN_SAR] = main_link->sample_aspect_ratio.num ?
+ (double) main_link->sample_aspect_ratio.num / main_link->sample_aspect_ratio.den : 1;
+ var_values[VARS_NB + VAR_S2R_MAIN_DAR] = var_values[VARS_NB + VAR_S2R_MDAR] =
+ var_values[VARS_NB + VAR_S2R_MAIN_A] * var_values[VARS_NB + VAR_S2R_MAIN_SAR];
+ var_values[VARS_NB + VAR_S2R_MAIN_HSUB] = 1 << main_desc->log2_chroma_w;
+ var_values[VARS_NB + VAR_S2R_MAIN_VSUB] = 1 << main_desc->log2_chroma_h;
+ }
+
/* evaluate width and height */
av_expr_parse_and_eval(&res, (expr = w_expr),
- var_names, var_values,
+ names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, log_ctx);
eval_w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
if ((ret = av_expr_parse_and_eval(&res, (expr = h_expr),
- var_names, var_values,
+ names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
goto fail;
eval_h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
/* evaluate again the width, as it may depend on the output height */
if ((ret = av_expr_parse_and_eval(&res, (expr = w_expr),
- var_names, var_values,
+ names, var_values,
NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
goto fail;
eval_w = res;