Beamforming and dereverbaration

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Suf
Posts: 2
Joined: Thu Feb 20, 2020 1:30 pm

Beamforming and dereverbaration

Post by Suf » Thu Feb 20, 2020 1:37 pm

Hi!

Thank you for this brilliant, open-source, piece of software.

I have a few questions which I'm hoping to get some help and understand.

1. Following your live Gain example, I'm trying to connect to JACK, apply some gain, but instead of playing this through the speakers, I'd like to record this on a file. Is it possible to use to iolibs at once? Any tips or pointers to do so?

2. Using your binaural beamforming example, I'm trying to tweak it to work for 8 mics instead of just 4. What would I need to do in that case? Would I need to generate vectors and place them on a text file as the example does?

3. I'm trying to apply some dereverberation on a music file recorded from a microphone. Would the coherence example help in this case?

Thank you in advance!

hendrikkayser
Posts: 20
Joined: Fri May 10, 2019 7:58 am

Re: Beamforming and dereverbaration

Post by hendrikkayser » Thu Feb 20, 2020 3:27 pm

Hello!

re 1.: It is not possible to use two iolibs, but you can add the plugin 'wavrec' to your mhachain to record audio.

re 2.: You'll find a description of the structure required for the file containing the filter coefficients in the documentation of the acSteer plugin in the plugin manual (www.openmha.org/docs/openMHA_plugins.pdf).

re3.: The coherence filter computes coherence values between two audio input channels. If two mics were used for the recording, give it a try! An play a little with the parameters...

I hope this helps!

Suf
Posts: 2
Joined: Thu Feb 20, 2020 1:30 pm

Re: Beamforming and dereverbaration

Post by Suf » Thu Feb 20, 2020 5:16 pm

Brilliant, thank you!

Is there a plugin for openMHA or some kind of python script that can help me create this file needed by acSteer?

hendrikkayser
Posts: 20
Joined: Fri May 10, 2019 7:58 am

Re: Beamforming and dereverbaration

Post by hendrikkayser » Thu Feb 27, 2020 12:57 pm

Unfortunately, we don't have a proper script at hand at the moment and I'm aware that we need to provide one in the future. The computation of the MVDR beamformer from head-related transfer functions is described in this contribution presented at the ITG Conference on Speech Communication 2016:

www.sigproc.uni-oldenburg.de/download/p ... 016_17.pdf

fam
Posts: 15
Joined: Wed Apr 14, 2021 1:24 am

Re: Beamforming and dereverbaration

Post by fam » Tue Apr 20, 2021 10:51 am

I'm wondering if there is an available plugin to create the file needed by acSteer?

hendrikkayser
Posts: 20
Joined: Fri May 10, 2019 7:58 am

Re: Beamforming and dereverbaration

Post by hendrikkayser » Tue Apr 20, 2021 7:01 pm

Sorry, no tool is available, yet.

fam
Posts: 15
Joined: Wed Apr 14, 2021 1:24 am

Re: Beamforming and dereverbaration

Post by fam » Wed Apr 21, 2021 6:23 am

Thank you for your reply.

fam
Posts: 15
Joined: Wed Apr 14, 2021 1:24 am

Re: Beamforming and dereverbaration

Post by fam » Thu Apr 22, 2021 9:37 am

I'm trying to apply the "steerbf" plugin to my data.
I know the steering angle. I find out that I can fix the steering angle by the "angle_ind" variable. In the "Documentation of openMHA plugins", section "9.5.4 Configuration variables", page 85, the angle_ind is defined as "Sets the steering angle in filtering. Range: [0,1000]". The range says it is an index, not an angle!

So, for example, if the steering vector is set in the range of -180:5:180, if I want to fix the "steering angle=0" the angle_ind should be set to 36 (index) or 0 (angle)?

hendrikkayser
Posts: 20
Joined: Fri May 10, 2019 7:58 am

Re: Beamforming and dereverbaration

Post by hendrikkayser » Thu Apr 22, 2021 2:17 pm

You're right - it's an index, not an angle. It points to the corresponding entry in the filter coefficient matrix.
In your example 36 is the correct choice.

fam
Posts: 15
Joined: Wed Apr 14, 2021 1:24 am

Re: Beamforming and dereverbaration

Post by fam » Fri Apr 30, 2021 10:27 am

Sorry for my delay to thank you for your reply.

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