Years ago I ran into the same dropout issue when switching partconv~ IR that could not be solved by multiplexing with smooth overlap. Back then I had a look into the C code and (off the top of my head) my conclusion was that it might be a CPU spike related to the underlying FFTW library making a new "plan" for optimal FFT calculation every time when partconv~ switches filter definition (even when filter length remains unaltered). If that is true, not easy to fix.
Katja
On 5/3/21, Gloria Dal Santo gloria.dalsanto@outlook.it wrote:
Hi everyone,
After playing with partconv~ in other to implement a patch for sound externalization I am asking myself whether what I am trying to do is maybe too much for pure data or not.
To sum up, I need to convolve a sound file with a BRIR that is updated whenever the listener moves his head, so that to simulate a fixed sound source. I already have a dataset of 36 impulse responses, each of size 8192 samples.
[partconv~] allows to change the impulse response by sending a [set ir_name( message. (For [convolve~] the message would be [set ir_name( ). Unfortunately, as soon as I send the [set _ ( message the audio stopes for a little while. Why is it so? I tried to dig into the code and I guess is simply because the buffers are freed when the set method is called.
I tried to define larger buffers so that I can store multiple BRIRs and have access to them without freeing the buffers (even though extra care must be taken in the perform method) but I think I don’t have enough coding skills to do that.
I then tried to use 5 [partconv~]s for each channel (thus 10 [partconv~]s) running at the same time with different BRIRs and multiplexing between them. The idea is that of switching between the outputs of the [partconv~] that are not updating their BRIRs, while one of the [partconv~] is actually updating it according to the direction of the head. To achieve this I’m using the [mux~] object. The idea seems working, but it actually doesn’t. When I switch between [mux~] inputs sometimes I get clicks. On the spectrogram these look like vertical lines of constant values (like noise). What could be the reason? Do you think that having 10 [partconv~] running at the same time is too much?
Thank you in advance for your time, With my best regard,
Gloria