[FFmpeg-devel] [PATCH] lavfi/scale: accept named option, make parsing more robust

[Stefano Sabatini]

On date Sunday 2012-10-28 19:51:01 +0100, Michael Niedermayer encoded:
> On Sun, Oct 28, 2012 at 05:33:37PM +0100, Stefano Sabatini wrote:
[...]
> > Subject: [PATCH] lavfi/scale: accept named option, make parsing more robust
> > 
> > Also update documentation accordingly.
> > 
> > TODO: bump micro
> [...]
> > @@ -76,7 +77,8 @@ typedef struct {
> >       *  -1 = keep original aspect
> >       */
> >      int w, h;
> > +    const char *flags_str;      ///sws flags string
> 
> 
> > -    unsigned int flags;         ///sws flags
> > +    int         flags;          ///sws flags
> 
> this doesnt look correct

Bummer, fixed.

[...]
> >  static av_cold int init(AVFilterContext *ctx, const char *args)
> >  {
> >      ScaleContext *scale = ctx->priv;
> > -    const char *p;
> > +    static const char *shorthand[] = { "w", "h", NULL };
> > +    int ret;
> >  
> > -    av_strlcpy(scale->w_expr, "iw", sizeof(scale->w_expr));
> > -    av_strlcpy(scale->h_expr, "ih", sizeof(scale->h_expr));
> > +    scale->class = &scale_class;
> > +    av_opt_set_defaults(scale);
> > +
> > +    if ((ret = av_opt_set_from_string(scale, args, shorthand, "=", ":")) < 0)
> > +        return ret;
> > +
> > +    av_log(ctx, AV_LOG_VERBOSE, "w:%s h:%s flags:%s interl:%d\n",
> > +           scale->w_expr, scale->h_expr, scale->flags_str, scale->interlaced);
> >  
> >      scale->flags = SWS_BILINEAR;
> > -    if (args) {
> > -        sscanf(args, "%255[^:]:%255[^:]", scale->w_expr, scale->h_expr);
> > -        p = strstr(args,"flags=");
> > -        if (p) {
> > -            const AVClass *class = sws_get_class();
> > -            const AVOption    *o = av_opt_find(&class, "sws_flags", NULL, 0,
> > -                                               AV_OPT_SEARCH_FAKE_OBJ);
> > -            int ret = av_opt_eval_flags(&class, o, p + 6, &scale->flags);
> > -
> > -            if (ret < 0)
> > -                return ret;
> > -        }
> > -        if(strstr(args,"interl=1")){
> > -            scale->interlaced=1;
> > -        }else if(strstr(args,"interl=-1"))
> > -            scale->interlaced=-1;

> > +    if (scale->flags_str) {
> > +        const AVClass *class = sws_get_class();
> > +        const AVOption    *o = av_opt_find(&class, "sws_flags", NULL, 0,
> > +                                           AV_OPT_SEARCH_FAKE_OBJ);
> > +        int ret = av_opt_eval_flags(&class, o, scale->flags_str, &scale->flags);
> > +        if (ret < 0)
> > +            return ret;
> >      }
> 
> I think it would be better if all options would be sent straight to
> sws instead of being parsed into a local AVClass based context.

Uhm, do you mean also w and h? How to deal with expressions?

> later requires every option to be duplicated and be kept in sync.

> also this fails with multiple (sws_)flags options that is like
> flags=+abc:flags=-abc
 
> if w/h need special handling then they could be intercepted and
> handlded special instead of being sent to sws.

This is not supported also in current version. This could be
implemented by returning the options which could not be set (and would
be useful in other places as well - e.g. the movie source/sink), but
I'd prefer to leave this to a separate change to avoid to make this
patch even more painful than it currently already is.
-- 
FFmpeg = Fundamental and Faithful Mortal Portable Elitarian Gangster
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