[aubio-user] Offset detection

[Paul Brossier]

On 06/01/2014 05:58, Lukasz Tracewski wrote:
> Hi Paul,
>
> Thanks for the prompt answer.
>
> I am trying to make a freeware software for identification of bird
> calls in noisy conditions.

I assume you mean free and open source software, not freeware?

> One of critical points in the task is to correctly identify "audio
> feature" (e.g. a bird call). As you can imagine length of a call is
> not fixed and distance from onset to onset in not necessarily call
> length. That is why I am looking for offset detection mechanism.
>
> If I need to retrieve both onset and offset, should I then use
> aubionotes instead of aubioonset?

It would help to have an example of the kind of annotations you want.

I guess aubionotes would not be appropriate, since it quantizes
frequency to integer midi notes.

You could just use aubiopitch. by setting the confidence and silence
thresholds appropriately, you should get 0.00 when the bird is not singing.

By the way, I would be very interested to have a small sample of songs
and the 'ground-truth' annotations you are looking for.

Regards, Paul

>
>
> Cheers, Lucas
>
> On 04/01/14, *Paul Brossier * <piem at piem.org> wrote:
>> On 04/01/2014 06:00, Lukasz Tracewski wrote:
>>> Hi,
>>>
>>> Aubio has a plethora of great onset detection methods. How about
>>> offset detection? I can imagine that running algorithm on
>>> reverse-ordered data should provide me with offsets, but maybe
>>> there is a smarter approach that I am missing.
>>
>> Hi Lukasz,
>>
>> There is no offset detection method in aubio (yet). The onset
>> detection functions will sometimes peak during the transient sound
>> created by the release of a note, but these peaks are expected be
>> small compared to the ones produced by note onsets.
>>
>> So far, offsets times are assumed to be where the level of the
>> signal drops under a given threshold. aubionotes for instance uses
>> a simple silence gate to determine the end of notes.
>>
>> What kind of offsets are you looking at? Do you have a specific
>> algorithm in mind?
>>
>> There is the work of Emmanouil Benetos and Simon Dixon, who use a
>> Hidden Markov Model to determine whether a pitch track is active
>> or not:
>>
>> http://www.eecs.qmul.ac.uk/~simond/pub/2011/Benetos-Dixon-ICASSP2011.pdf
>>
>>
>>
>>
>>
>>
>>
>>
Best, Paul
>>
>>
>>>
>>> Thanks, Lucas
>>>
>>>
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