TECHNICAL DATA
Contextualisation
Visual feedback for audio representation has been used from the early 40s with the first VU meters [1]. Later, but still on the analogue era, more colourful audio meters started to appear on the market, like the famous Dorrough 400 series [2]. Visual feedback for audio has been used not only for metering the loudness, but also to show FFT analysis, or stereo correlation such as the DK-Audio MSD600 [3] or the newest TC-Electronics Clarity-M [4].
In terms of spacial audio, most of the previously mentioned products have their own 5.1 or even 7.1 version, but at the moment, any ambisonics 3D audio hardware device has been released. There exist some software-based tools like the Ambi-head [5] or the Waves 360 tools [6], but even though they use colours and graphs, they are trying to represent 3D audio in a 2D screen. That is why AMBFEED has a market niche to explore and develop, aiming to represent 3D audio in a 3D hardware sphere. |
Technical description
The AMBFEED sphere comes with a VST/AU plug-in, ready to run on any VST/AU host. However, it needs to be plugged after an AMBIX decoder [7] plug-in using the 50-speaker Lebedev rig [8] configuration file from the SADIE database [9]. The AMBIX decoder will give 50 audio signals, which have be to routed to the AMBFEED plug-in. Inside the plug-in, a 300 milliseconds RMS of each signal is calculated and then translated to brightness for the LEDs.
The plug-in sends OSC messages, which are received in a Processing [10] application. This application works as a bridge between the software and the hardware part, translating the OSC to Serial messages, which are finally sent to the Arduino [11] via USB. The code used in Processing is a modified version of the SparkFun tutorial 152 [12]. Using the library made by Alex Leone [13], when the Arduino receives the messages, it sends the brightness of the received LED to the TLC5940 digital PWM multiplexers. The TLC5940 chips can multiplex up to 16 LEDs each, and have 4096 brightness steps resolution. In addition, they can be installed in daisy-chain mode, using only four outputs of the Arduino. |
Demo video test
In this video, a 5th order ambisonics mix, extracted from the York Test database from the AES Immersive and Interactive Audio Conference 2019, plays back a voice-over that says (and sounds at) a location in the 3D space. Using headphones, it is possible to hear the direction and see the AMBFEED in action.
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References:
[1] H. Chinn, D. Gannett and R. Morris, "A New Standard Volume Indicator and Reference Level", Proceedings of the IRE, vol. 28, no. 1, pp. 1-17, 1940.
[2] "Dorrough", Dorrough.com, 2019. [Online]. Available: https://www.dorrough.com/. [Accessed: 18- Apr- 2019].
[3] K. Hansen, "DK-Meter, Solutions in Audio and Video", Hansens.dk, 2019. [Online]. Available: http://www.hansens.dk/index.php. [Accessed: 18- Apr- 2019].
[4] Tcelectronic, Clarity M, 2019. [Online]. Available: https://www.tcelectronic.com/Categories/Tcelectronic/Signal-Processors/Meters/CLARITY-M-STEREO/p/P0DC8#googtrans(en|en). [Accessed: 18- Apr- 2019]
[5] "Ambi Head HD | Noise Makers", Noise Makers, 2019. [Online]. Available: https://www.noisemakers.fr/ambi-head-hd/. [Accessed: 18- Apr- 2019].
[6] "360° Ambisonics Mixing Tools | Waves", waves.com, 2019. [Online]. Available: https://www.waves.com/hardware/360-ambisonics-tools#tab-includes. [Accessed: 18- Apr- 2019].
[7] "ambiX v0.2.7 – Ambisonic plug-in suite | matthiaskronlachner.com", Matthiaskronlachner.com, 2019. [Online]. Available: http://www.matthiaskronlachner.com/?p=2015. [Accessed: 18- Apr- 2019].
[8] P. Lecomte, P. Gauthier, C. Langrenne, A. Berry and A. Garcia, "A Fifty-Node Lebedev Grid And Its Applications To Ambisonics", Journal of the Audio Engineering Society, vol. 64, no. 11, pp. 868-881, 2016.
[9]"SADIE | Spatial Audio For Domestic Interactive Entertainment", 2019. [Online]. Available: https://www.york.ac.uk/sadie-project/. [Accessed: 18- Apr- 2019].
[10] "Processing.org", Processing.org, 2019. [Online]. Available: https://processing.org/. [Accessed: 18- Apr- 2019].
[11] "Arduino - Home", Arduino.cc, 2019. [Online]. Available: https://www.arduino.cc/. [Accessed: 18- Apr- 2019].
[12] "Controlling an Arduino with an iPhone - SparkFun Electronics", Sparkfun.com, 2009. [Online]. Available: https://www.sparkfun.com/tutorials/152. [Accessed: 10- March- 2019].
[13] A. Leone, "TLC5940 Arduino Library", Code.google.com, 2019. [Online]. Available: https://code.google.com/archive/p/tlc5940arduino/. [Accessed: 18- Apr- 2019].
[2] "Dorrough", Dorrough.com, 2019. [Online]. Available: https://www.dorrough.com/. [Accessed: 18- Apr- 2019].
[3] K. Hansen, "DK-Meter, Solutions in Audio and Video", Hansens.dk, 2019. [Online]. Available: http://www.hansens.dk/index.php. [Accessed: 18- Apr- 2019].
[4] Tcelectronic, Clarity M, 2019. [Online]. Available: https://www.tcelectronic.com/Categories/Tcelectronic/Signal-Processors/Meters/CLARITY-M-STEREO/p/P0DC8#googtrans(en|en). [Accessed: 18- Apr- 2019]
[5] "Ambi Head HD | Noise Makers", Noise Makers, 2019. [Online]. Available: https://www.noisemakers.fr/ambi-head-hd/. [Accessed: 18- Apr- 2019].
[6] "360° Ambisonics Mixing Tools | Waves", waves.com, 2019. [Online]. Available: https://www.waves.com/hardware/360-ambisonics-tools#tab-includes. [Accessed: 18- Apr- 2019].
[7] "ambiX v0.2.7 – Ambisonic plug-in suite | matthiaskronlachner.com", Matthiaskronlachner.com, 2019. [Online]. Available: http://www.matthiaskronlachner.com/?p=2015. [Accessed: 18- Apr- 2019].
[8] P. Lecomte, P. Gauthier, C. Langrenne, A. Berry and A. Garcia, "A Fifty-Node Lebedev Grid And Its Applications To Ambisonics", Journal of the Audio Engineering Society, vol. 64, no. 11, pp. 868-881, 2016.
[9]"SADIE | Spatial Audio For Domestic Interactive Entertainment", 2019. [Online]. Available: https://www.york.ac.uk/sadie-project/. [Accessed: 18- Apr- 2019].
[10] "Processing.org", Processing.org, 2019. [Online]. Available: https://processing.org/. [Accessed: 18- Apr- 2019].
[11] "Arduino - Home", Arduino.cc, 2019. [Online]. Available: https://www.arduino.cc/. [Accessed: 18- Apr- 2019].
[12] "Controlling an Arduino with an iPhone - SparkFun Electronics", Sparkfun.com, 2009. [Online]. Available: https://www.sparkfun.com/tutorials/152. [Accessed: 10- March- 2019].
[13] A. Leone, "TLC5940 Arduino Library", Code.google.com, 2019. [Online]. Available: https://code.google.com/archive/p/tlc5940arduino/. [Accessed: 18- Apr- 2019].