Friday, January 22, 2016

Record Binaural 3D Audio using Android devices

After i heard some Binaural audios i wanted to build some myself. I made some Binaural sounds using 2 recorders but that was not comfortable and precise. So i started building my own Android app to record Binaural audios. Here i demonstrate my app how to use it and following it i will describe how to make Binaural recordings without using my app. In case you don't have 2 devices or Android.

My app Binaural-3DAudio-Recorder is available at PlayStore. Below are images from help presentation of the app.


PlayStore link:
play.google.com/store/apps/details?id=org.greh.binaural_3daudio_recorder


My apps website:
www.gamesgreh.in


















































Build Binaural Audio Using Audacity from app's exported audio.


Audacity its an OpenSource multi-platform (Linux, Mac, Windows etc) freeware.
  • In Android App, After recording was done. Go to export tab and press export. Ignore rest of things.  
  • Transfer Exported ogg file from Android device to PC. 
  • Install & start Audacity in PC. Drag and drop the copied ogg file over Audacity app. 
  • After the file is imported it will look like below pic with a green eclipse. The eclipse shows the Shift Tool ↔ 
  • The audio must be split into 2 mono files. i.e. Left and Right audio must be separated. Pictures below illustrate these all steps described here. 
  • Use shift tool to move any of these audio tracks to match the waveforms. Use zoom tool to see waveforms closely before shifting. 
  • After shifting the track(s) merge them back into stereo and export.  

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Click on Track Drop Down button and split Stereo to Mono.
Select Shift Tool and move any track so that both
matches as shown in both pics below. Below image shows waveforms are not in SYNC.

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Below image shows waveform on both tracks are close enough for sync.

[image]



Important note:
Matching & placing both waveforms doesn't always means best binaural audio. Suppose mics are separated far and audio comes at nearer mic first. This means there is a real difference in waveform which we are destroying by perfect waveform match. Therefore you should listen audio before finalizing it. This is the main reason i Or any other developer will not engage into perfect matching. Manual mixing is always the best!


Now merge both split tracks back to stereo.
[image]



Export Audio

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While exporting add your meta data
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Exported to file:


[image]




Now you are done with the final output :). I personally enjoy binaural audios. They are useful in many-many ways be it health sector or entertainment.



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