[Kdenlive-devel] Questions about audio effects

[Dan Dennedy]

2010/9/2 Hugh Tebby <hugh.tebby at gmail.com>:
> I was wrong, it wasn't the 1197 plugin that was used ;)
> I tested adding a new equalizer and it seems to work fine. I should send a
> patch this week-end if I have an internet connection. I'll try to also add
> more detailed or precise descriptions of audio effects.

We are beyond the string freeze date, and I will let JB decide how
that is handled. IMO, it is not that important for this release.
(Getting mlt-sox fixed is another matter.)

> By the way I had to make some code modifications in initEffects.cpp, and it
> seems a bit "hackish", having to activate the effect manually in the code,
> along with the parameters that were already specified in the xml file. There
> are also 4 ladspa effects that aren't treated the same way (nearly but not
> quite...), like the current equalizer effect for instance.
>
> I suppose there is a reason for this (maybe something to do with jack ?),
> but it looks like this bit of code could be cleaned up and automated.

Not jack directly, but ladspa in mlt currently requires jackrack xml
as a specification of the plugins and their parameter values. This
means that multiple plugins can be chained in one MLT filter instance.
There are other advantages and use cases to justify this largely
outside of Kdenlive. When I add support for LV2 to MLT, I may make it
work without xml. Maybe we should reserve extensive rework of
initEffects.cpp for when we add LV2.

> 2010/9/2 Hugh Tebby <hugh.tebby at gmail.com>
>>
>> Hi Dan,
>>
>> I've just moved in a new flat, and have no internet access at home for a
>> few days. I'll hopefully have it back by this week-end.
>>
>> Just one thing : you said to use the mbeq 1197 ladspa plugin for the
>> equalizer in order to get more frequencies, but from what I remember it's
>> already that plugin that is used. I quickly tried to add new sliders in the
>> xml file (and modified a related piece of code) with no success, only the
>> three first sliders had an effect. I'll check again, maybe I got the plugin
>> name wrong or something.
>>
>>
>> Cheers,
>> Hugh
>>
>> 2010/9/1 Dan Dennedy <dan at dennedy.org>
>>>
>>> On Wed, Sep 1, 2010 at 12:31 AM, Dan Dennedy <dan at dennedy.org> wrote:
>>> >>>> - Gain: expecting dB instead of %, should be under "audio
>>> >>>> correction"
>>> >>>> folder
>>> >
>>> > The underlying mlt filter does accept a dB value, but I just had to
>>> > commit a change to let it accept negative values for db. However, if
>>> > we change it, then existing projects will have insane dB values
>>> > without doing some document conversion stuff, for which I think we are
>>> > out-of-time (I do not know anything about that).
>>>
>>> I was just editing normalise to use dB when I realized MLT requires
>>> that you suffix the value with "dB" otherwise it is interpreted as
>>> float (%), but Kdenlive effects XML system has no way to add that
>>> suffix. (It has a suffix it can display as a label in UI, but that is
>>> not added to the value passed to MLT.)
>>>
>>> --
>>> +-DRD-+
>>>
>>>
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>
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