RMS Waveform Analyser

[mixxxbot]

Reported by: esbrandt
Date: 2010-03-04T18:43:02Z
Status: Fix Released
Importance: Wishlist
Launchpad Issue: lp532090
Tags: waveform
Attachments: rms.patch

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Mik made this very useful patch back in January, i put it here on the Wishlist for reference.
Especially for very dynamic songs the RMS is way better then what we use today.

<snip>
Hello.

Waveform view on mixxx looks very spiky. This results from peak detection
algorithm that extract waveform envelop. Since in my eyes rms averaging is the
better, if programmed it into mixxx. On the links below one can compare peak
detection and rms averaging on a techno track and a rock song. It doesn't look
that much better like I had expected but when playing sound files even the
small spikes are very helpful by getting a feeling of the beats and rhythm
hidden behind the waveform.

http://img641.imageshack.us/i/mixxxpeak.png/
http://img52.imageshack.us/i/mixxxrms.png/

Since rms averaging requiers a lot cpu time performance is a critical issue. A
tricky alogrithm can reduce calculation afford with minor loss results. In
fact my variant is as fast as peak detection.

The attachment contains a patch made from revision 2293 with the changes I've
applied to implement rms averaging. The code is made with limit checking thus
at least critical bugs which make mixxx instable are very unlikely.

Also there is an open issue. I'm not a daily C++ programmer but if 
WaveformAnalyser object is destroy QVector<float> is freed as well.

In hope I could help

mik
</snip>

[mixxxbot]

Commented by: esbrandt
Date: 2010-03-04T18:43:02Z
Attachments: rms.patch

[mixxxbot]

Commented by: 4chons
Date: 2010-03-06T11:48:32Z

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Sorry for the silly question, but how do I apply this patch? :)

[mixxxbot]

Commented by: esbrandt
Date: 2010-03-06T12:23:12Z

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Copy rms.patch to mixxx` trunk root directory on your hd. Navigate in terminal to that directory using cd.

Type in terminal

patch -p0 <rms.patch

Message about patched analyzerwaveform.cpp & analyzerwaveform.h should be displayed.

Good HOWTO on applying patches can be found at
http://drupal.org/patch/apply

[mixxxbot]

Commented by: rryan
Date: 2012-04-03T20:49:19Z

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waveform-2.0 branch uses RMS energy for the waveforms

[mixxxbot]

Issue closed with status Fix Released.