[FFmpeg-devel] [PATCH] [RFC] Add option for writing detailed filtergraph information to file or stdout

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Nicolas George
> Sent: Thursday, 26 August 2021 09:40
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH] [RFC] Add option for writing
> detailed filtergraph information to file or stdout
> 
> Soft Works (12021-08-26):
> > The purpose is to get a precise and detailed view of the
> filtergraphs
> > at runtime including all connections with their negotiated formats
> and
> > media types.
> 
> I asked the purpose, you are rephrasing what the patch does.

Okay, then let's go back a few years and I'll tell you about my
original motivation. 

I often did not understand why filters couldn't connect to each other
or when they did - how they actually connected and which format was 
actually used between them.
In many cases, this wasn't clear from the log output.

I've also seen that the format filter got inserted quite often, but 
I wanted to know exactly where it gets inserted and from which
to which format it converts in each case.

Another aspect that I needed to understand precisely was the use
of formats in case of hw acceleration (sw pixel format); there
was no way to see what was being used and negotiated.

We are covering a wide range of platforms and hardware accelerations
and the requirements are complex: deinterlacing, scaling, color 
conversion, tone mapping, overlay of graphical and textual subtitles, 
etc. and all that in arbitrary combinations with almost all
ffmpeg-supported hwas. All that needs to work as good as possible
on all older and newer hardware, which is not a trivial task.

I'm using the output that this patch is creating either for diagnosing,
either by manual review or in combination with another tool
that allows to visualize those filtergraphs like I had shown last year:

https://github.com/softworkz/ffmpegfiltergraphs/issues/1

Does that answer your question?

Kind regards,
softworkz