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Sampling rates, input domain and sonification

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justin:

--- Quote from: cannam on July 12, 2012, 14:27:41 ---
--- Quote from: justin on July 12, 2012, 14:10:55 ---Extra question 1: from the programmer's guide I take it the first block is not centred on time zero but rather starts at the first sample of the audio right? (double checking, as this could cause alignment issues when checking against ground-truths centred on time 0).

--- End quote ---

Depends on the host, but you can tell from the timestamp provided.

The docs (http://code.soundsoftware.ac.uk/embedded/vamp-plugin-sdk/classVamp_1_1Plugin.html#ae4aed3bebfe80a2e2fccd3d37af26996) say that "[t]he timestamp will be the real time in seconds of the centre of the FFT input window". Therefore, if the first timestamp is zero, that should mean you are being passed a window centred on the start of the audio rather than starting with the first sample.

--- End quote ---

Just in case anyone is following this thread - I just realised this is not the case if you use the time domain input - in that case the timestamp will be of the beginning of the block! Sorry Chris, I realise that's stated quite clearly in the link you posted, I should've read it more carefully.

Anyway, for those of us working with time-domain input, if you want "correct" timestamps you should add windowduration/2 to your timestamps (where windowduration is expressed in seconds, i.e. m_blockSize / inputSampleRate).

Cheers

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