[FFmpeg-devel] [PATCH 4/4] Make the crop filter accept parametric expressions.

[Stefano Sabatini]

On date Friday 2010-09-17 12:09:04 +0200, Michael Niedermayer encoded:
> On Wed, Sep 15, 2010 at 12:28:06AM +0200, Stefano Sabatini wrote:
> [...]
> > +static inline int normalize_double(int *n, double d)
> > +{
> > +    int ret = 0;
> > +
> > +    if (isnan(d)) {
> > +        ret = AVERROR(EINVAL);
> > +    } else if (d > INT_MAX || d < INT_MIN) {
> > +        *n = d > INT_MAX ? INT_MAX : INT_MIN;
> > +        ret = AVERROR(EINVAL);
> > +    } else
> 
> > +        *n = d;
> 
> something that rounds to nearest should be used

round()

> > +
> > +    return ret;
> > +}
> > +
> >  static int config_input(AVFilterLink *link)
> >  {
> >      AVFilterContext *ctx = link->dst;
> >      CropContext *crop = ctx->priv;
> >      const AVPixFmtDescriptor *pix_desc = &av_pix_fmt_descriptors[link->format];
> > +    int ret;
> > +    const char *expr;
> > +    double res;
> > +
> > +    crop->var_values[E]     = M_E;
> > +    crop->var_values[PHI]   = M_PHI;
> > +    crop->var_values[PI]    = M_PI;
> > +    crop->var_values[IN_W]  = crop->var_values[IW] = ctx->inputs[0]->w;
> > +    crop->var_values[IN_H]  = crop->var_values[IH] = ctx->inputs[0]->h;
> > +    crop->var_values[X]     = NAN;
> > +    crop->var_values[Y]     = NAN;
> > +    crop->var_values[OUT_W] = crop->var_values[OW] = NAN;
> > +    crop->var_values[OUT_H] = crop->var_values[OH] = NAN;
> > +    crop->var_values[N]     = 0;
> 
> T/POS are random?

Fixed, set now to NAN.

> >      av_image_fill_max_pixsteps(crop->max_step, NULL, pix_desc);
> >      crop->hsub = av_pix_fmt_descriptors[link->format].log2_chroma_w;
> >      crop->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;
> >  
> > -    if (crop->w == 0)
> > -        crop->w = link->w - crop->x;
> > -    if (crop->h == 0)
> > -        crop->h = link->h - crop->y;
> > +    if ((ret = av_parse_and_eval_expr(&res, (expr = crop->ow_expr),
> > +                                      var_names, crop->var_values,
> > +                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
> > +    crop->var_values[OUT_W] = crop->var_values[OW] = res;
> > +    if ((ret = av_parse_and_eval_expr(&res, (expr = crop->oh_expr),
> > +                                      var_names, crop->var_values,
> > +                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
> > +    crop->var_values[OUT_H] = crop->var_values[OH] = res;
> > +    /* evaluate again ow as it may depend on oh */
> > +    if ((ret = av_parse_and_eval_expr(&res, (expr = crop->ow_expr),
> > +                                      var_names, crop->var_values,
> > +                                      NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
> > +    crop->var_values[OUT_W] = crop->var_values[OW] = res;
> > +    if (normalize_double(&crop->w, crop->var_values[OUT_W]) < 0 ||
> > +        normalize_double(&crop->h, crop->var_values[OUT_H]) < 0) {
> > +        av_log(ctx, AV_LOG_ERROR,
> > +               "Too big value or invalid expression for out_w/ow or out_h/oh. "
> > +               "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
> > +               crop->ow_expr, crop->oh_expr);
> > +        return AVERROR(EINVAL);
> > +    }
> > +    crop->w &= ~((1 << crop->hsub) - 1);
> > +    crop->h &= ~((1 << crop->vsub) - 1);
> > +
> > +    if ((ret = av_parse_expr(&crop->x_pexpr, crop->x_expr, var_names,
> > +                             NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||
> > +        (ret = av_parse_expr(&crop->y_pexpr, crop->y_expr, var_names,
> > +                             NULL, NULL, NULL, NULL, 0, ctx)) < 0)
> > +        return AVERROR(EINVAL);
> >  
> > +    crop->var_values[X] = av_eval_expr(crop->x_pexpr, crop->var_values, NULL);
> > +    crop->var_values[Y] = av_eval_expr(crop->y_pexpr, crop->var_values, NULL);
> > +    /* evaluate again x as it may depend on y */
> > +    crop->var_values[X] = av_eval_expr(crop->x_pexpr, crop->var_values, NULL);
> > +    if (normalize_double(&crop->x, crop->var_values[X]) < 0 ||
> > +        normalize_double(&crop->y, crop->var_values[Y]) < 0) {
> > +        av_log(ctx, AV_LOG_ERROR,
> > +               "Too big value or invalid expression for x or y. "
> > +               "Maybe the expression for x:'%s' or for y:'%s' is self-referencing.\n",
> > +               crop->x_expr, crop->y_expr);
> > +        return AVERROR(EINVAL);
> > +    }
> 
> i dont think that will work they can depend on N/T/POS which should be NAN for W/H

Changed the logic, now x/y is evaluated only in start_frame(), a
default value is set in case the first evaluated x/y is not valid.
This way the filter won't fail if the initial value of x/y is not
invalid (and the last valid value is used).

Regards.
-- 
FFmpeg = Fascinating and Fostering MultiPurpose Extroverse Gnome