[FFmpeg-devel] Plans for libavfilter

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Nicolas George
> Sent: Thursday, 16 September 2021 13:55
> To: ffmpeg-devel at ffmpeg.org
> Subject: [FFmpeg-devel] Plans for libavfilter
> 


> 
> 
> - Media type negotiation.
> 
>   That means that filters that do not care about the contents of what
>   they are filtering, filters that only act on the frame information
>   fields, can also not care if they are filtering audio or video or
>   other. There are a lot of these filters: pts manipulation, concat,
>   split, selection, etc.
> 
>   We cannot afford to have to update every one of them if we want to
> add
>   a new media type, so this is a prerequisite. And it is an aspect of
>   multi-stage negotiation, since pixel format or sample format can
> only
>   be negotiated once we know the media type.

I don't see any benefit in having filters that are handling variable 
media types. 
Even when the filter names are the same, the semantic of what these 
are doing often varies significantly.
They would often need to have options where some only apply to a certain
media type only.
Further, this increases error and confusion for command line use, as
this would lead to filters connecting in ways that aren't intended
at all, while making it hard for users to understand what's happening
and why it's failing.
It's already hard or impossible to see which formats are actually
negotiated between filters. Having filters that can do multiple 
media types on a single pad would cause ultimate confusion for users
and make things happen that are undesired, unexpected and intransparent.

Kind regards,
softworkz