[FFmpeg-devel] [PATCH v2 7/8] avfilter/sleet: Add sleet filter

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Moritz Barsnick
> Sent: Friday, 3 September 2021 10:24
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH v2 7/8] avfilter/sleet: Add sleet
> filter
> 
> On Tue, Aug 31, 2021 at 22:49:12 +0000, Soft Works wrote:
> > As for the "sleet" filter: Yes - it is totally useless for
> practical
> > use. I had explained why I added it in the 0/8 message:
> >
> > > Why leet? Real world use is surely questionable, but it has two
> advantages
> > > that make it a great choice for testing:
> > > You can see from almost every single line whether it has been
> filtered,
> > > and the text is still readable which allows to verify that
> timings are
> > > still valid.


Hi Moritz,

thanks for looking into my patchset!

> 
> Okay, I get that case, though it seems a bit special. Isn't this just
> a
> debug feature for developers then?

Yes, correct. Or probably rather a demo and also (like you mentioned)
boilerplate code.

Finally, I'll also need to add Fate tests for this new capability and
that requires to have a simple filter as well.

> A review of this boilerplate would be great.
> 
> For the sake of review:
> - You need to add documentation to doc/filters.texi.

Yes, I'm already working on it.

> - You need to bump MINOR in libavfilter/version.h.

I think it even needs a MAJOR bump due to the change in 1/8 to 
AVFrame.

> 
> > Maybe an "sallcaps" filter makes slightly more sense than "sleet"?
> 
> For the sake of usability, I would rather have suggested something
> like
> "tr" (https://linux.die.net/man/1/tr,
> https://www.geeksforgeeks.org/perl-tr-operator/), where you can
> specify
> the replacement list. That said, tr has some funky shortcuts ("[a-z]
> [A-Z]" for uppercase, which may be harder to implement). Or actual
> regular expression support.
> 
> What I suggest is still not really useful for a user, though. Or is
> it?

I'm not sure - probably this would be ranking similarly to sleet and 
sallcaps ;-)

One kind of text filter that would be both, simple and useful would 
be something like "saddname".

With ASS subtitles, the name of the speaking person is often included
in the event data and sometimes subtitles can be confusing as to who
is actually speaking or it would be helpful to see character names
to better understand and follow.
So, what "saddname" would do is simply to change an event like:

338,0,Default,John,0000,0000,0000,,Hey, welcome!

to

338,0,Default,John,0000,0000,0000,,JOHN: Hey, welcome!


The reason why I did sleet instead is that it will always have a visible
effect while saddname would appear non-functional in case when 
character names are missing in the subtitle events.

Though, I don't have any feelings regarding sleet and I'd be totally
fine to drop it in the final version of the patchset.

Thanks,
softworkz