int ff_scale_eval_dimensions(void *log_ctx, const char *w_expr, const char *h_expr, AVFilterLink *inlink, AVFilterLink *outlink, int *ret_w, int *ret_h) { const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format); const AVPixFmtDescriptor *out_desc = av_pix_fmt_desc_get(outlink->format); const char *expr; int w, h; int factor_w, factor_h; int eval_w, eval_h; int ret; double var_values[VARS_NB], res; var_values[VAR_PI] = M_PI; var_values[VAR_PHI] = M_PHI; var_values[VAR_E] = M_E; var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w; var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h; var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN; var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN; var_values[VAR_A] = (double) inlink->w / inlink->h; var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ? (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1; var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR]; var_values[VAR_HSUB] = 1 << desc->log2_chroma_w; var_values[VAR_VSUB] = 1 << desc->log2_chroma_h; var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w; var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h; /* evaluate width and height */ av_expr_parse_and_eval(&res, (expr = w_expr), var_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, 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, NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0) goto fail; eval_w = res; w = eval_w; h = eval_h; /* Check if it is requested that the result has to be divisible by a some * factor (w or h = -n with n being the factor). */ factor_w = 1; factor_h = 1; if (w < -1) { factor_w = -w; } if (h < -1) { factor_h = -h; } if (w < 0 && h < 0) eval_w = eval_h = 0; if (!(w = eval_w)) w = inlink->w; if (!(h = eval_h)) h = inlink->h; /* Make sure that the result is divisible by the factor we determined * earlier. If no factor was set, it is nothing will happen as the default * factor is 1 */ if (w < 0) w = av_rescale(h, inlink->w, inlink->h * factor_w) * factor_w; if (h < 0) h = av_rescale(w, inlink->h, inlink->w * factor_h) * factor_h; *ret_w = w; *ret_h = h; return 0; fail: av_log(log_ctx, AV_LOG_ERROR, "Error when evaluating the expression '%s'.\n" "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n", expr, w_expr, h_expr); return ret; }