[FFmpeg-devel] [PATCH] avfilter: add loudnorm

[Kyle Swanson]

On Wed, Apr 6, 2016 at 5:31 PM, Paul B Mahol <onemda at gmail.com> wrote:
> On 4/6/16, Kyle Swanson <k at ylo.ph> wrote:
>> On Wed, Apr 6, 2016 at 10:02 AM, Clement Boesch <u at pkh.me> wrote:
>>> On Wed, Apr 06, 2016 at 09:52:51AM -0500, Kyle Swanson wrote:
>>>> On Wed, Apr 6, 2016 at 12:45 AM, Clement Boesch <u at pkh.me> wrote:
>>>> > On Tue, Apr 05, 2016 at 07:01:14PM -0500, Kyle Swanson wrote:
>>>> >> Here's another audio filter. I hinted at this a few months ago, but I
>>>> >> found out that
>>>> >> finishing the last 5% took almost as long as the first 95%. This is an
>>>> >> EBU R128
>>>> >> dynamic loudness normalization filter. This filter uses libebur128
>>>> >> v1.1.0[1] and must be
>>>> >> configured with `--enable-libebur128'. Please also see the
>>>> >> accompanying blog post[2]
>>>> >> which has an algorithm description, as well as some usage
>>>> >> instructions.
>>>> >>
>>>> >> [1] https://github.com/jiixyj/libebur128
>>>> >> [2] http://k.ylo.ph/2016/04/04/loudnorm.html
>>>> >>
>>>> >> Thanks!
>>>> >> Kyle
>>>> >>
>>>> >> Signed-off-by: Kyle Swanson <k at ylo.ph>
>>>> >> ---
>>>> >>  Changelog                 |   1 +
>>>> >>  MAINTAINERS               |   1 +
>>>> >>  configure                 |   5 +
>>>> >>  doc/filters.texi          |  42 +++
>>>> >>  libavfilter/Makefile      |   1 +
>>>> >>  libavfilter/af_loudnorm.c | 905
>>>> >> ++++++++++++++++++++++++++++++++++++++++++++++
>>>> >>  libavfilter/allfilters.c  |   1 +
>>>> >>  libavfilter/version.h     |   4 +-
>>>> >>  8 files changed, 958 insertions(+), 2 deletions(-)
>>>> >>  create mode 100644 libavfilter/af_loudnorm.c
>>>> >>
>>>> >
>>>> > Mmh. That's nice and all but... why not use/adjust the native ebur128
>>>> > filter we have instead of relying on an external library?
>>>> >
>>>> > [...]
>>>> >
>>>> > --
>>>> > Clement B.
>>>>
>>>> This could be an option for the future. We'll need to break all the
>>>> EBU R128 logic out into utility functions
>>>
>>> why? what do you need exactly from the filter? The meta are exported in
>>> each audio frame.
>>
>> That could work, but in this filter there is a second internal
>> loudness measurement. Frame meta would only work for the input stream.
>
> Couldn't code from ebur128 filter be refactored in such way so it
> could be used by loudnorm?
>

Yeah, that's what I was saying. It could be done, but might take a
little while. I figure libebur128 could work fine in the meantime.
Would probably also be useful for filters like astats.

>>
>>>
>>>> and update it to use the newest version BS.1770 so it can be used by
>>>> both filters. Using libebur128 is a
>>>> good option because it is widely used, actively developed, and updated
>>>> whenever the spec changes.
>>>
>>> except it's an external dependency and we have code builtin available,
>>> doing the same thing, and with no open issue (afaik).
>>>
>>> --
>>> Clement B.
>>>
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>>>
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