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

[Paul B Mahol]

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?

>
>>
>>> 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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