[FFmpeg-devel] [PATCH v2 4/8] avfilter/overlay_subs: Add overlay_subs filter

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Paul B Mahol
> Sent: Monday, 30 August 2021 20:10
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH v2 4/8] avfilter/overlay_subs: Add
> overlay_subs filter
> 
> NACK, code duplicated.

Thanks for looking at my patch. While the code is based on the overlay
filter's code, there are substantial differences:

The overlay functions are taking AVSubtitleRect images for overlay,
which are PAL8 images and those need quite a bit different treatment.
For example, I'm only converting the 256 palette entries from RGBA to  
YUVA for effective blending.
With those differences, it doesn't make sense to merge this 
into the existing functions in vf_overlay as it would result in ugly
code which would be hard to maintain.


There's unnecessary duplication though, between the new sub2video
filter and the overlay_subs filter. I am planning to merge these
into a single file as a next step.

I'm planning to rename like this:

- overlay_graphicsubs (this filter)
- graphicsubs2video (in the same file)


Analog to these I will submit the following two filters:

- overlay_textsubs
- textsubs2video (in the same file)

=> the current subtitles filter can be deprecated then
   (with overlay_textsubs, it won't be required anymore
    to open the input separately)


Finally, I'm planning to add a modified eia608 filter variant:

- eia608_split (video-in, video-out, subtitles-out)

=> it won't be required anymore to use the movie protocol
   for getting closed captions


Please let me know whether it makes sense to you.

Thanks,
softworkz