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ambisonictoolkit / atk-reaper

Ambisonic Toolkit as a set of JSFX plugins for the REAPER DAW.
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Encoding from all Reaper's supported surround formats? #49

Open joslloand opened 8 years ago

joslloand commented 8 years ago

This will require:

We'll be able to implement this feature when matrix loading has been implemented.

Related to https://github.com/ambisonictoolkit/atk-reaper/issues/48

joslloand commented 8 years ago

Just a thought... we may be interested in providing a pseudo-inverse form. That's more of a very expert user thing, so probably isn't necessary for the general user.

joslloand commented 8 years ago

ReaSurround (Cockos) - Presets

Reaper's ReaSurround surround panner is presented as a "hockey puck" style panner. While we haven't made any further investigations as to the algorithm used, it does appear to be a power (VBAP-style) intensity panner, with the addition of a "diffusion" parameter to add contribution by additional loudspeakers.

The tables below indicate output channels in the order they appear. Listed azimuth and elevation observe the Ambisonic convention.

Names given are those presented in ReaSurround. The specified values may or may not conform to any proposed or recognised standard.

stereo outputs: 2

Name [azi, ele]
left [90, 0]
right [-90, 0]

Notes: Appears to have the intention of modeling the spaced AB microphone technique. I expect the modeling is gain only, though, as there are no parameters to set the speed of sound and distance in meters.

quadrophonic outputs: 4

Name [azi, ele]
front left [45, 0]
front right [-45, 0]
back left [135, 0]
back right [-135, 0]

octophonic outputs: 8

Name [azi, ele]
front left [45, 0]
front center [0, 0]
front right [-45, 0]
side right [-90, 0]
back right [-135, 0]
back center [180, 0]
back left [135, 0]
side left [90, 0]

Note: "Stonehenge array", clockwise from front left.

octophonic box outputs: 8

Name [azi, ele]
front left [45, 0]
front right [-45, 0]
back left [135, 0]
back right [-135, 0]
front left height [45, 35]
front right height [0, 35]
back left height [-45, 35]
back right height [-90, 35]

Note: Quadrophonic array with an additional elevated quadrophonic array (+35deg). This is ~1/2 of a cube. Apparently intended to add height to the quadrophonic array.

5.1 surround outputs: 6

Name [azi, ele]
front left [45, 0]
front right [-45, 0]
front center [0, 0]
LFE [--, --]
back left [135, 0]
back right [-135, 0]

Note: The quadrophonic array, but with the addition of front center and LFE.

7.1 surround outputs: 8

Name [azi, ele]
front left [45, 0]
front right [-45, 0]
front center [0, 0]
LFE [--, --]
back left [135, 0]
back right [-135, 0]
side left [90, 0]
side right [-90, 0]

Note: The 5.1 surround array, but with the addition of side left and side right.

9.1 surround outputs: 10

Name [azi, ele]
front left [45, 0]
front right [-45, 0]
front center [0, 0]
LFE [--, --]
back left [135, 0]
back right [-135, 0]
side left [90, 0]
side right [-90, 0]
left height [63, 42]
right height [-63, 42]

Note: The 7.1 surround array, but with the addition of left height and right height.

5.1 ITU-R outputs: 6

Name [azi, ele]
front left [30, 0]
front right [-30, 0]
front center [0, 0]
LFE [--, --]
side left [110, 0]
side right [-110, 0]

Note: Recommended ITU-R 5.1 array, as found in Recommendation ITU-R BS.775.

7.1 ITU-R outputs: 8

Name [azi, ele]
front left [30, 0]
front right [-30, 0]
front center [0, 0]
LFE [--, --]
side left [110, 0]
side right [-110, 0]
back left [150, 0]
back right [-150, 0]

Note: ITU-R 5.1 array, with the addition of back left and back right. Does not conform to any of the recommended 7.1 arrays appearing in Report BS.2159: FIGURE 24: Examples of loudspeaker mapping of 7.1 channel sound. It appears that Reaper's 7.1 ITU-R is an ad hoc array created by adding two additional back speakers.

9.1 ITU-R outputs: 10

Name [azi, ele]
front left [30, 0]
front right [-30, 0]
front center [0, 0]
LFE [--, --]
side left [110, 0]
side right [-110, 0]
back left [150, 0]
back right [-150, 0]
left height [45, 45]
right height [-45, 45]

Note: Reaper's ITU-R 7.1 array, with the addition of left height and right height. Report BS.2159 does not recommend any 9.1 loudspeaker arrays. It appears that Reaper's 9.1 ITU-R is an ad hoc array created by adding two additional front elevation speakers to Reaper's 7.1 ITU-R array.

joslloand commented 8 years ago

The two ITU documents with relevant recommendations are: