[FFmpeg-devel] Filters

[Clément Bœsch]

On Fri, Jul 18, 2014 at 12:56:17PM +0100, JULIAN GARDNER wrote:
> >________________________________
> > From: Clément Bœsch <u at pkh.me>
> >To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org> 
> >Sent: Friday, 18 July 2014, 13:38
> >Subject: Re: [FFmpeg-devel] Filters
> > 
> >
> >On Fri, Jul 18, 2014 at 12:08:41PM +0100, JULIAN GARDNER wrote:
> >> How do I fix a filter so that it takes in 1 input but has no output, this is part of a project and this part is a detection filter, it does nothing else.
> >> 
> >> The problem at the moment is that with the current filter, based on drawbox, is that it produces an output which i need to the use overlay to dump.
> >> 
> >> Is there a video filter which has 1 input but 0 outputs
> >
> >Just make a passthrough filtering (ff_filter_frame(in)), and do not map
> >its output
> >
> 
> 
> Can you elaborate a bit more as I have this code as my base code
> 
> 
> static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
> {
>     DrawBoxContext *s = inlink->dst->priv;
>     int plane, x, y, xb = s->x, yb = s->y;
>     unsigned char *row[4];
> 
>     // Detect Stationary Object
>     ....
> 
>     // Here I would like to dump the frame as it is no longer needed
> 
>     return ff_filter_frame(inlink->dst->outputs[0], frame);
> }
> 

You do exactly that and that's all. Then ffmpeg -i foo -vf bar -f null -

There are a lot of detection only filters. volumedetect, signalstats,
blackdetect, ... just copy their behaviour

[...]

-- 
Clément B.
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