[FFmpeg-devel] [PATCH] avfilter/avfilter: Fix hardcoded input index

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Soft Works
> Sent: Sunday, 5 September 2021 16:59
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH] avfilter/avfilter: Fix hardcoded
> input index
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Paul B Mahol
> > Sent: Sunday, 5 September 2021 11:01
> > To: FFmpeg development discussions and patches <ffmpeg-
> > devel at ffmpeg.org>
> > Subject: Re: [FFmpeg-devel] [PATCH] avfilter/avfilter: Fix
> hardcoded
> > input index
> >
> > With what filters this happens?
> >
> > IIUC this is forbidden and such filters should use .activate
> instead.
> 
> The hardcoded [0] is wrong, no matter what the use case is.
> 
> But to answer your question: It's about a new overlay_textsubs filter
> where framesync cannot be used and incoming frames (video on input0,
> subs on input1) need to be processed independently: the subtitle
> events
> are fed into the ass library (you could practically feed all events
> in advance) while the overlay image generation is done based on a
> given
> time code.
> This works fine by having a separate .filter_frame function for each
> input (after applying this patch).

BTW

> > IIUC this is forbidden and such filters should use .activate

The scale2ref filter is set up in the same way (two .filter_frame
functions, no .activate, no framesync), probably because - like in 
my case - the filter must not sync frames across inputs.

softworkz