The SOPA technology allows you to create media art with the immersive sound and share it with the world.
On this site, we provide a Java program 'wav2sopa' that can be used to generate a panoramic sound stream from stereo .wav files so that you can make your own panoramic sound clips and save them to the local disk.
To generate a SOPA file, you have to provide a pair of stereo WAV files that were obtained by a 4-track recording with a tetrahedral microphone system.
Download the Java program -> 'wav2sopa.jar.'
What you need is to develop your own tetrahedral microphone system that consists of 4 omnidirectional microphones. Four microphones have to be placed at the vertices of a tetrahedron as illustrated in Fig. 1.
Each side of the tetrahedron (microphone distance) should have length between 10 mm and 30 mm (the recommended value is between 10 mm and 20 mm).
Figure 2 shows an example of the tetrahedral microphone system.
You also need to have a multi-track audio interface with microphone amplifiers for the 4-track recording. You may use, for examples, ROLAND OCTA-CAPTURE, PreSonus AudioBox 44VSL, and so on.
You can also use a multi-track recorder (MTR) with microphone amplifiers (for examples, TASCAM DR-680, ZOOM H6).
Since there are 4 tracks, 2 stereo WAV files will be generated in the recording. Configure your system so that the signal flow is as illustrated in Fig. 4.
Many of the commercial DAW softwares support multitrack recording and you can use one of them.
If you use a stand-alone MTR, you have to transmit the data to your PC from the MTR.
In a recording, synchronization of the tracks is crucial. If the synchronization latency is not small enough, little effect or even no effect is expected.
The synchronization latency may depend on either the software or the audio interface. If you use Roland OCTA-CAPTURE, for example, set the 'audio buffer size' to 'Min.' in the 'Driver Settings.'
Make the peak level several dB below digital full scale to prevent clipping.
Since the panoramic sound renderer on this site is for evaluation, there are the following restrictions.
When a 4-track recording is done, you are supposed to have a pair of stereo WAV files. Let's call them 'aaa.wav' and 'bbb.wav.'
Extract the files from the Java Archive file wav2sopa.jar, read 'readme.pdf' and follow the instructions so that you can generate a SOPA file out of the 2 WAV files 'aaa.wav' and 'bbb.wav.'
The line below is the command line to extract files from the .jar file.
Once the SOPA file is generated successfully, it can be saved to the local directory and can be used for free.
The main window of 'wav2sopa' looks like Fig. 5. The main window has 3 buttons and a combo box.
Please notice that the size of the SOPA file is comparable to the stereo WAV file.
If you have SOPA files in your local disk, you can play them in https://staff.aist.go.jp/ashihara-k/SopaLoc.html.
If you send your SOPA files to your friends' PCs, friends of yours can also play them in https://staff.aist.go.jp/ashihara-k/SopaLoc.html.
By using SopaJS, you can make a Web page full of immersive panoramic sounds.
Once you created your own panoramic sound (SOPA) files and their corresponding full-spherical video (MP4) files, why don't you publish them over Internet?
You do not have to write program code by yourself. You can make the Web page with panoramic sound and full-spherical video by using QuickStart package.
See quick for detail.
SOPA files that are generated by 'wav2sopa' can be used freely. However, if you publish them on your Web site or somewhere else, please give a credit to https://staff.aist.go.jp/ashihara-k/pan_top.html.
Create the immersive virtual reality experience and share it with the world.