static inline int set_options(AVFilterContext *ctx, const char *args)
{
    HueContext *hue = ctx->priv;
    int n, ret;
    char c1 = 0, c2 = 0;
    char   *old_hue_expr,  *old_hue_deg_expr,  *old_saturation_expr;
    AVExpr *old_hue_pexpr, *old_hue_deg_pexpr, *old_saturation_pexpr;

    if (args) {
        /* named options syntax */
        if (strchr(args, '=')) {
            old_hue_expr        = hue->hue_expr;
            old_hue_deg_expr    = hue->hue_deg_expr;
            old_saturation_expr = hue->saturation_expr;

            old_hue_pexpr        = hue->hue_pexpr;
            old_hue_deg_pexpr    = hue->hue_deg_pexpr;
            old_saturation_pexpr = hue->saturation_pexpr;

            hue->hue_expr     = NULL;
            hue->hue_deg_expr = NULL;
            hue->saturation_expr = NULL;

            if ((ret = av_set_options_string(hue, args, "=", ":")) < 0)
                return ret;
            if (hue->hue_expr && hue->hue_deg_expr) {
                av_log(ctx, AV_LOG_ERROR,
                       "H and h options are incompatible and cannot be specified "
                       "at the same time\n");
                hue->hue_expr     = old_hue_expr;
                hue->hue_deg_expr = old_hue_deg_expr;

                return AVERROR(EINVAL);
            }

            SET_EXPRESSION(hue_deg, h);
            SET_EXPRESSION(hue, H);
            SET_EXPRESSION(saturation, s);

            hue->flat_syntax = 0;

            av_log(ctx, AV_LOG_VERBOSE,
                   "H_expr:%s h_deg_expr:%s s_expr:%s\n",
                   hue->hue_expr, hue->hue_deg_expr, hue->saturation_expr);

        /* compatibility h:s syntax */
        } else {
            n = sscanf(args, "%f%c%f%c", &hue->hue_deg, &c1, &hue->saturation, &c2);
            if (n != 1 && (n != 3 || c1 != ':')) {
                av_log(ctx, AV_LOG_ERROR,
                       "Invalid syntax for argument '%s': "
                       "must be in the form 'hue[:saturation]'\n", args);
                return AVERROR(EINVAL);
            }

            if (hue->saturation < SAT_MIN_VAL || hue->saturation > SAT_MAX_VAL) {
                av_log(ctx, AV_LOG_ERROR,
                       "Invalid value for saturation %0.1f: "
                       "must be included between range %d and +%d\n",
                       hue->saturation, SAT_MIN_VAL, SAT_MAX_VAL);
                return AVERROR(EINVAL);
            }

            hue->hue = hue->hue_deg * M_PI / 180;
            hue->flat_syntax = 1;

            av_log(ctx, AV_LOG_VERBOSE,
                   "H:%0.1f h:%0.1f s:%0.1f\n",
                   hue->hue, hue->hue_deg, hue->saturation);
        }
    }

    compute_sin_and_cos(hue);

    return 0;
}