HOA Tutorial Exercise 08

Extension

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Next: HOA Tutorial Exercise 09

The example below shows how to record the b-format within the proxy space.

In case you have not done so yet: let's start the sound server, which we configure first to get more audio buses and to have 36 output channels.s.quit; // quit the server first if it is still running with another configuration. ( ServerOptions.devices; s = Server.local; Server.local = Server.default; o = Server.local.options; // Get the local server's options o.numInputBusChannels = 2; // Set Input to number of Inputs o.numOutputBusChannels = 36; // lets start after chan 36 so as not to see the mic input o.numAudioBusChannels = 2048; o.blockSize = 512; o.numWireBufs = 1024 * 16; o.memSize = 2.pow(18); o.sampleRate = 48000; s.makeWindow; s.boot; )

Start the oscilloscope showing all the channels for the selected order of the b-format.( ~order = 3; ~hoaNumChannels = (~order+1).pow(2); s.scope(2); // let's use only two channels as we will monitor it with headphones )

Let's make a node that picks up the SoundIn (microphone) and spatializes it in a HOA signal we spatialize it a spherical wave and we have it move vertically and change the distance with oscillators( ~hoaSignal = NodeProxy.new(s, \audio, ~hoaNumChannels); ~hoaSignal.source = {HOAEncoder.ar(~order, SoundIn.ar(0), // this picks up the Microphone 0, // no azimuth movement SinOsc.ar(0.3, 0, 90 ), // changing elevation plane_spherical:1, // we want it to be a spherical wave radius:SinOsc.ar(0.4, 0, 2, 2 ) // and change the radius )}; ~hoaSignal.fadeTime = 1; ) Then we make a node that rotates this signal in the x/y plane. This is the node that we want to record from, that's why we use a RecNodeProxy: code:: ( ~hoaTransformer = RecNodeProxy.new(s, \audio, ~hoaNumChannels); ~hoaTransformer.source = {var in; in = \in.ar(0!~hoaNumChannels); HOATransRotateAz.ar(~order, in, SinOsc.ar(0.5, 0, pi ) ) }; ~hoaTransformer.fadeTime = 1; )

Then we make the usual decoding and listening node and we connect themHOADecLebedev26.loadHrirFilters(s); ( ~decoderOrder = 2; // let's reduce the order ~decoderNumChannels = (~decoderOrder+1).pow(2); ~decoder = NodeProxy.new(s, \audio, 2); ~decoder.source = {var in; in = \in.ar(0!~decoderNumChannels); HOADecLebedev26.ar(~decoderOrder, in, hrir_Filters:1) }; ~decoder.fadeTime = 1; ~decoder.play(0, 2); ~hoaSignal <>> ~hoaTransformer <>> ~decoder; )

Open the recording file, start recording, unpause, pause and, when finished, close the file:~hoaTransformer.open( thisProcess.platform.userHomeDir++"/HOArecordingTest.wav", "wav", "float" ); // lets record it in float ~hoaTransformer.record // start recording (paused) ~hoaTransformer.unpause // unpause ~hoaTransformer.pause // pause again ~hoaTransformer.close // close the file

Normalize the resulting sound file, evaluate line by line:~buffer2Normalize = Buffer.read(s, thisProcess.platform.userHomeDir++"/HOArecordingTest.wav"); ~buffer2Normalize.normalize.write(thisProcess.platform.userHomeDir++"/HOArecordingTestN.wav", "wav", "int16"); // and safe it as "int16" to safe space

Now let's listen to the recorded sound file by opening it first:~hoaSoundFile = Buffer.read(s, thisProcess.platform.userHomeDir++"/HOArecordingTestN.wav");

Then we change the ~hoaSignal.source to play back the sound file, and we want to just pass the signal through the transformer without additional rotation:( ~hoaSignal.source = { HPF.ar(PlayBuf.ar( ~hoaSoundFile.numChannels, ~hoaSoundFile, loop:1 ), 100) }; ~hoaTransformer.source = {var in; in = \in.ar(0!~hoaNumChannels); in }; )

Finally we delete the files:File.delete(thisProcess.platform.userHomeDir++"/HOArecordingTest.wav"); File.delete(thisProcess.platform.userHomeDir++"/HOArecordingTestN.wav");

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Next: Exercise_09_HOA_decoding_for_speaker_arrays