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Home Software (Windows & Mac OSX) Four Channel Ambiophonic Transcoder

Four Channel Ambiophonic Transcoder

Download the JAVA-Application (version 1.0 - 11/02/2010) AmbiophonicTranscoder4Ch.zip (20kByte) which works for Windows, Mac and Linux.

If you don't have the JRE (JAVA Runtime Environment) installed then you'll get it here: http://www.java.com/download/manual.jsp


The Principles of Ambiophonics*:

1.) Ambiophonics uses RACE* (Recursive Ambiophonic Crosstalk Elimination) to enable binaural listening
2.) The Speakers are positioned with a separation angle smaller than 20° (called Ambiodipol) instead of 60° used in stereo. No worries, in contrast to stereo, the sound stage goes far beyond the boundaries set by the speakers (up to 120°).

Reference:
- RACE is a free algorithm made available by the Ambiophonics Institute (http://www.ambiophonics.org)
- Ambiophonics has been invented by the Ambiophonics Institute


Key advantages in comparison to stereo by playing the same material from CD, LPs or your computer:

1.) Elimination of Comb filtering effects and pinna direction finding errors
2.) By having the speakers close together reflections by walls and the bass mode response of the room are much easier to control
3.) The center presence is very stable and therefore always easy to locate


Listening Experience:

The sound stage gets a strong deepness, height and wideness which creates a real three dimensional listening experience.
Locating a single sound source within the original stereo image is much easier with Ambiophonics. You're able to pinpoint each instrument in all three dimensions!
To achieve optimal cross talk cancellation Ambiophonics has a sweet spot (similar to stereo) along the median line where the sound stage has its best representation.


Which records sound best?

In contrast to the standard stereo setup where spatially rich recordings that contain binaural cues with inter-aural time differences (ITD) loose their deepness, Ambiophonic plays back a much richer sound stage.
Many productions mix monaural microphones or direct sources between channels to create phantom images limited to inter-aural level differences (ILD), but even those recordings do get a wider and more precise sound stage with Ambiophonics.


The Four Channel Ambiophonic Transcoder


What does the program do?
In comparison to the Ambiophonic Transcoder which uses two input channels to apply the Recursive Ambiophonic Crosstalk Elimination (RACE), the Four Channel Ambiophonic Transcoder offers 3 different operationg modes:
1.) 2 Input- and 2 Output-Channels to apply standard RACE on stereo material
2.) 2 Input- and 4 Output-Channels to expand 2 channel stereo to 4 channel Ambiophonics
3.) 4 Input- and 4 Output-Channels to convert multi channel source material (e.g. Dolby 5.1) into 4 channel Ambiophonics


Installation:

The Four Channel Ambiophonic Transcoder has been developed in JAVA to assure maximum cross platform compatibility for Windows, Mac and Linux. There is no need for any installation, just unzip and launch the JAR-File. As a pre-condition you need to have the JRE (Java Runtime Environment) installed which you can download here: http://java.com/download/manual.jsp


Setting up your listening environment:

1.) Place your speakers in a separation angle of around 20°. The speakers do need a good phase response, but even simple single driver PC-Speaker work well.
2.) Your listening position needs to be equidistant to the front and rear speakers
3.) Make sure that you activate the audio input and output devices you want to use by applying the appropriate operating system configuration. Furthermore, it is essential to adjust the input-level to avoid overmodulation of the input signal.
4.) Launch the Ambiophonic Transcoder without changing the attenuation and delay
5.) Select the Input- and Output-Mixer
6.) Click activate to start the sampling and play back process
7.) Feed in some music, like vocal/instrumental recordings where you know that those contain inter-aural time differences (ITD)
8.) Move along the median of the speakers until you find the best sound stage experience

GUI Elements

File Menu:
It is possible to save all configuration parameters.

Activate/Deactivate:
Activates the audio sampling and playback process. The application needs a couple of seconds until the buffers are filled to play distortion free.

Sample Frequency:
The transcoder supports 16Bit samples with a sample frequency of 44.1kHz, 48kHz and 96kHz.

Standard / Buffer Size:
The right buffer size assures distortion free play back. A bigger buffer implies a longer latency which can be a problem in combination with video playback (lip sync). If "Standard" is selcted then the program uses the operating system's standard buffer length.

Latency:
The latency is directly related to the selected buffer length.

 

Channel Mapping:
There are three operationg modes:
1.) 2 > 2: 2 Input- and 2 Output-Channels to apply standard RACE on stereo material
2.) 2 > 4: 2 Input- and 4 Output-Channels to expand 2 channels stereo to 4 channel Ambiophonics
3.) 4 > 4: 4 Input- and 4 Output-Channels to convert multi channel source material (e.g. Dolby 5.1) into 4 channel Ambiophonics

Input- and Output-Mixer Selection:
It is possible to choose any detected input- and output-mixer. The program needs to be restarted as soon as you add or remove sound devices (e.g. USB-Audio Devices) to allow a new detection of the available mixer.

 

Recursive Ambiophonic Crosstalk Elimination Attenuation:
Increasing the attenuation value reduces the cross talk elimination which results in a smaller sound stage.

Center:
A higher center value reduces the crosstalk elimination of "equiphase/similar amplitude" signals to emphasize center sounds like vocals.

Delay:
The delay defines the time offset of the cross talk cancellation wavefront to make sure that the signal arrives the ear at the right point in time. The amount depends on speaker separation and listening distance. It is a good starting point to go for a speaker separation angle of 20° and a delay of around 70μs. Please keep in mind that the delay is a discrete value which changes in steps of "1/sampling frequency" (e.g 22.7μs for 44.1kHz or 10.4μs for 96kHz). If the sampling frequency changes then the program adapts the delay accordingly.

Frequency Limitation:
As default RACE works on a limited frequency range of 0Hz-4.5kHz by keeping all other frequencies untouched. Deselection of the checkbox activates Recursive Ambiophonic Crosstalk Elimination for all frequencies between 0Hz and 20kHz.

Bypass:
Selecting the checkbox activates transparent playback without applying RACE to allow comparison between Stereo and Ambiophonics.

 


Leveling:
The implementation of the RACE algorithm works with 64Bit values to keep the highest accuracy. Because of the 16Bit nature of audio samples there is a need for attenuation to correctly map the values, which works through automatic leveling allowing the use of the full 16Bit dynamic range.
Any 16Bit clipping triggers the auto leveling to reduce the amplitude by 0.1dB. Even in automatic mode your're able to decrease the attenuation up to 0dB, but the automatic will try to bring it back as soon as it sees overflows.
Finally, you can switch of the auto mechanism to adjust leveling manually to keep the overflows in an acceptable range.

Volume & Balance:
The volume and balance sliders change the main outputs.

 

Disclaimer and License:
This Software is provided "as-is", without any express or implied warranty.
In no event will the author be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software except for commercial use.
Please contact me (Stephan Hotto) if there is a wish for a commercial implementation.