[FFmpeg-devel] [PATCH] Configure graph filters with more than one output

[Vitor Sessak]

Stefano Sabatini wrote:
> Hi all,
> 
> I'm experimenting with a graph chain of this kind:
> ffplay in.avi -vfilters "split [out] [select], [select] select='eq(mod(N, 10), 0)', snapshot"

I suppose you mean

ffplay in.avi -vfilters "split [out] [select]; [select] 
select='eq(mod(N, 10), 0)', snapshot"

(note the ';')

or

ffplay in.avi -vfilters "split [out]  select='eq(mod(N, 10), 0)', snapshot"

?

> the problem is that the config_props of the snapshot is never called,
> since the code which do the configuration:
> 
>  if(avfilter_config_links(filt_out))                      goto the_end;
> 
> only configure the part of the graph from the application output
> filers towards the beginning.
> 
> Suggested function call avfilter_config_links(filt_out) on all the
> output filters of a graph (that is filters which one input and no
> output).

> +int avfilter_graph_config_links(AVFilterGraph *graph, AVClass *log_ctx)
> +{
> +    AVFilterContext *filt;
> +    int i, ret;
> +
> +    for (i=0; i < graph->filter_count; i++) {
> +        filt = graph->filters[i];
> +
> +        if (!filt->output_count) {
> +            if ((ret = avfilter_config_links(filt)))
> +                return ret;
> +        }
> +    }

Hmmm... I'm fine with the patch, but I think this makes the 
recursiveness of avfilter_config_links() useless. Since it doesn't work 
for the example you've given, I'd say it should be removed (but it can 
be another patch).

-Vitor