Find sound effect inside an audio file

Question

I have a load of 3 hour MP3 files, and every ~15 minutes a distinct 1 second sound effect is played, which signals the beginning of a new chapter.

Is it possible to

Answer 1

Trying to directly match waveforms samples in the time domain is not a good idea. The mp3 signal will preserve the perceptual properties but it is quite likely the phases of the frequency components will be shifted so the sample values will not match.

You could try trying to match the volume envelopes of your effect and your sample. This is less likely to be affected by the mp3 process.

First, normalise your sample so the embedded effects are the same level as your reference effect. Constructing new waveforms from the effect and the sample by using the average of the peak values over time frames that are just short enough to capture the relevant features. Better still use overlapping frames. Then use cross-correlation in the time domain.

If this does not work then you could analyze each frame using an FFT this gives you a feature vector for each frame. You then try to find matches of the sequence of features in your effect with the sample. Similar to https://stackoverflow.com/users/1967571/jonnor suggestion. MFCC is used in speech recognition but since you are not detecting speech FFT is probably OK.

I am assuming the effect playing by itself (no background noise) and it is added to the recording electronically (as opposed to being recorded via a microphone). If this is not the case the problem becomes more difficult.