[Kdenlive-devel] Questions about audio effects

Dan Dennedy dan at dennedy.org
Thu Jun 3 17:04:07 UTC 2010

2010/5/31 wille <wille.yyz at gmail.com>:
> Yes, left/right stereo balance.
> It would be very useful a feature that allow split a stereo audio clip in
> two mono clips.

Well, now you have requested two different new features when Hugh was
volunteering to do some cleanup. The lack of balance/pan is already
well known and on my todo list. I praise Hugh's interest in
volunteering for some cleanup and would be saddened to see him

One thing you can do today is to split the audio and video and add the
clip again on an audio track. Then, use the channelcopy filter on both
audio clips to isolate left vs. right. Finally, you can use the
keyframable volume effect on each to do panning. Unfortunately, today
channelcopy is exposed in Kdenlive as simply "Mono to stereo," but you
can alter the effect XML file for that to add "to" and "from" channel
parameters (0 is left, 1 is right). ("Mono to stereo" may seem like a
strange name, but it was added specifically for the case where a clip
only has a mono track and you do not want it both channels and not
just left.)

MLT and Kdenlive does not support the notion of a different number of
channels per track. So your second request is much longer term, if
ever, especially considering that I am still working on proper
multichannel (>2) support. I have been doing a lot with multichannel
in the past year for broadcast applications of MLT, but there are
still some gaps to add it in Kdenlive. One of these is surround
panning, which would also be capable of stereo.

> 2010/5/31 Hugh Tebby <hugh.tebby at gmail.com>
>> Do you mean left/right stereo balance ? I don't think there's such an
>> effect available in Sox or Ladspa... Would probably have to be done directly
>> with MLT...

That is correct.

>> 2010/5/31 wille <wille.yyz at gmail.com>
>>> By the way, I feel the need of a Balance audio effect or a similar tool.


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