[FFmpeg-devel] [PATCH] avfilter: merge loudnorm filter functionality into f_ebur128.c

[Kyle Swanson]

Hi,

On Sun, Nov 19, 2023 at 3:48 AM Paul B Mahol <onemda at gmail.com> wrote:
>
> On Fri, Nov 17, 2023 at 7:38 AM Kyle Swanson <k at ylo.ph> wrote:
>
> > Hi,
> >
> > On Wed, Nov 15, 2023 at 12:39 PM Paul B Mahol <onemda at gmail.com> wrote:
> > >
> > > Attached.
> >
> > Only had a few minutes to look at this. Seems like more than just
> > merging two filters, I see a bunch of new filter options for example.
> > Can you explain?
> >
>
> The linear mode and scanning, both input to filter and filter output itself
> should give similar results.
> The dynamic mode now actually can be configured how aggressively it will
> expand / compress audio.
> Because current state of filter have numerous issues:
>
>  - using unmaintained old libebur128 module, when same functionality is
> already available in existing filter.
>  - code duplication and functionality duplication due the above
>  - buggy limiter - causing clipped samples randomly
>  - buggy first and final frame filtering
>  - over-complicated flow path for dynamic code in filter
>  - excessive compressing of audio dynamic range, causing extreme smaller
> LRU from output audio
>  - and probably more that I forgot
>
> Some options from this patch can be probably removed, like attack/release
> options, and just use defaults as currently in patch.
>
>
> > Thanks,
> > Kyle

OK. Give me some time to review this. Unfortunately, I can't be quick
since it is a Holiday week here and the diff is pretty hard to read.
I'm hoping this still gives exact/equivalent loudnorm output, since
this is a pretty widely used filter. My first reaction is combining
the filters like this might make things more complicated, but I will
keep an open mind while reviewing.

Thanks,
Kyle