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Re: Audio Time and/or Level Alignment Algorithm



Hi Dan and All,

Thanks for Dan's suggestion. Actually, I have also tried to use mutual information, however, I found these methods are not available for all audio signals, for example, one method is effective for to speech, but it maybe disabled for music. In addition, the delay maybe time-varying, so I didn't find a reliable estimation method to compute the time delay.

Thanks a lot.

BR, Junyong

----- Original Message ----- From: "Dan Stowell" <dan.stowell@xxxxxxxxxxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx>
Sent: Thursday, July 03, 2008 1:52 PM
Subject: Re: [AUDITORY] Audio Time and/or Level Alignment Algorithm



Hi -

You might like to consider using mutual information as an alternative to cross-correlation. The advantage is that cross-correlation is always about the linear dependencies between the signals, whereas the mutual information can also highlight nonlinear dependencies (for example, in your case, the codec may have added compression).

Dan



Junyong You wrote:
Hi John and all,

In fact, I am also looking for the time alignment of two samples, one is the original, and another is decoded. My problem is to estimate the time delay caused by audio coding.

I try a classifical estimation method, which makes use of envelope based cross-correlation function. That means, the envelopes of two samples are computed firstly, and then calculate the cross correlation function of these two envelopes, and then select the time length corresponding to the maximal correlation as the delay.

I hope this method will help you, and if anyone has better approaches, please let me know, thank you very much.

BR,  Junyong You

TUT, Finland
----- Original Message ----- From: John Spencer To: AUDITORY@xxxxxxxxxxxxxxx Sent: Wednesday, July 02, 2008 2:11 PM
Subject: [AUDITORY] Audio Time and/or Level Alignment Algorithm




  Hello List,



  I am looking for advice and help with a problem.



I have 2 audio signals each recorded in different environments but both are the same length. I need to align them the best I can or align at leats one of them to match the other. They need to be aligned time wise and level wise if possible. Any advice appreciated, thanks.



John Spencer ------------------------------------------------------------------------------

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--
Dan Stowell
Centre for Digital Music
Queen Mary, University of London
Mile End Road, London E1 4NS
http://www.elec.qmul.ac.uk/department/staff/research/dans.htm
http://www.mcld.co.uk/