Filter applause from videos

Question

I asked this question before on stackoverflow ( http://stackoverflow.com/questions/5299338/filter-applause-from-videos ) and got the hint to ask it here:

I am currently watching a video from 27C3 and I would like to filter the applause, as it is very loud. Is this possible? I have heard something like this was made for Vuvuzelas.

I use Ubuntu. If this filter would work via ffmpeg / Audacity this would be great. If it is written in Python it would also be ok. I know the normalization with the VLC-Player, but thats not a very good solution

Here is an example: http://www.youtube.com/watch?v=TIViQuCX7XM#t=5m4s

Answer 1

Vuvuzelas are easily filterable because they are using is a specific frequency. Applause are basically random "clicks" which use a lot of the spectrum, and as such can't really be filterable. You could possibly detect applause and automatically lower the volume. But it's probably not trivial.

You might be able to get a good enough result by using a compressor or limiter, as that will lower the volume when it's high.

Answer 2

It sounds like you want to do this on the fly for your viewing pleasure. Unfortunately, sound engineers will recommend that you manually clean up your audio for the best result.

This can be done in various ways. It sounds as though the camera's mic was used to capture audio, as the audience is louder than the stage. Therefore you will have some trouble removing audience noise while the stage is performing. It is possible, however. I recommend you use a tracker with good envelopes or a waveform editor with a pencil tool. It's not procedure that can be taught in a paragraph. If you really want to do it, why not ask another question relating to that.

As far as automatic filtering, you've probably done the searches. Good luck.

Answer 3

You're not going to be able to filter the applause out without creating an underwater/comb filtered sound that would make the audio unintelligible at best. That is due to the very nature of applause. It's not a uniform tone like a vuvzela.

However, if your issue is that the applause is too loud you can combat the volume changes with a compressor. You would want a reasonably strong compression, so that the volume change between applause, and no applause is negligible. But it will depend heavily on the content you throw at it. So a one size fits all approach may be hard to find.