[Numpy-discussion] "Dynamic convolution" in Numpy

[David Huard]

On Thu, Jun 3, 2010 at 9:52 AM, arthur de conihout <
arthurdeconihout at gmail.com> wrote:

> Hi,
> thanks for your answer
>
> *why don't you compute all possible versions beforehand*
>
>
> thats exactly what i m doing presently cause i m using a 187 filters
> database(azimuth and elevation).I would love to be able to reduce the angle
> thread under 5° which triggers around 1000 files to produce.For a 3Mb
> original sound file, it becomes huge.
>
> Indeed ! I'll be curious to see what solutions ends up working best. Keep
us posted.

David


> Thanks
>
> Arthur
>
>
> 2010/6/3 David Huard <david.huard at gmail.com>
>
> Hi Arthur,
>>
>> I've no experience whatsoever with what you are doing, but my first
>> thought was why don't you compute all possible versions beforehand and then
>> progressively switch from one version to another by interpolation between
>> the different versions. If the resolution is 15 degrees, there aren't that
>> many versions to compute beforehand.
>>
>> David
>>
>> On Thu, Jun 3, 2010 at 6:49 AM, arthur de conihout <
>> arthurdeconihout at gmail.com> wrote:
>>
>>> Hello everybody
>>>
>>> i m fighting with a dynamic binaural synthesis(can give more hints on it
>>> if necessary).
>>>
>>> i would like to modify the sound playing according to listener's head
>>> position. I got special filters(binaural ones) per head position that i
>>> convolve in real time with a monophonic sound.When the head moves i want to
>>> be able to play the next position version of the stereo generated sound but
>>> from the playing position(bit number in the unpacked datas) of the previous
>>> one.My problem is to hamper audible artefacts due to transition.
>>> At moment i m only using *short audio wav* that i play and repeat if
>>> necessary entirely because my positionning resolution is 15°
>>> degrees.Evolution of head angle position let time for the whole process to
>>> operate (getting position->choosing corresponding filter->convolution->play
>>> sound)
>>>
>>> *For long **audio wav* I could make a fade-in fade-out from the
>>> transition point but i have no idea how to implement it(i m using audiolab
>>> and numpy for convolution)
>>>
>>> An other solution could be dynamic filtering means when i change position
>>> i convolve the next position filter from the place the playing must stop for
>>> the previous one(but won't pratically stop to let the next convolution
>>> operates on enough frames) in accordance with the filter frame length(all
>>> the filters are impulse response of the same lenght 128).
>>>
>>> The "drawing" i introduce just below is my mental representation of what
>>> i m looking to implement, i already apologize for its crapitude (and one of
>>> my brain too):
>>>
>>>
>>> t0_________t1__t2__t3___________________________________________________________t=len(stimulus)
>>> monophonic sound(time and bit position in the unpacked datas)
>>>
>>> C1C1C1C1C1C1C1C1C1C1C1...
>>> running convolution with filter 1 corresponding to position 1 (ex: angle
>>> from reference=15°)
>>>
>>>    P1_______
>>>    sound playing 1
>>>
>>>                    ^
>>>                    position 2 detection(angle=30°)
>>>
>>>                    C2C2C2C2C2C2C2C2C2C2C2...
>>>                    running convolution with filter 2
>>>
>>>                    P1_____x
>>>                    keep playing 1 for convolution 2 to operate on enough
>>> frames (latency)
>>>
>>>                            FIFO
>>>                            fade in fade out
>>>
>>>                                 P2_________
>>>                                 sound playing 2
>>>
>>>
>>> I don't know if i made myself very clear.
>>>
>>> if anyone has suggestions or has already operated a dynamic filtering i
>>> would be well interested.
>>>
>>> Cheers
>>>
>>> Arthur
>>>
>>>
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>>>
>>>
>>
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