ChannelInterpretation

The ChannelInterpretation type specifies how the input channels are mapped to the output channels when the channel counts differ.

Acceptable values:

• speakers

  Uses a set of standard mapping rules for all combinations of common input and output setups.

• discrete

  Covers all other cases. Mapping depends on the relationship between the number of input channels and the number of output channels.

Channels mapping table

speakers

Number of input channels	Number of output channels	Mixing rules
1 (Mono)	2 (Stereo)	output.L = input.M output.R = input.M
1 (Mono)	4 (Quad)	output.L = input.M output.R = input.M output.SL = 0 output.SR = 0
1 (Mono)	6 (5.1)	output.L = 0 output.R = 0 output.C = input.M output.LFE = 0 output.SL = 0 output.SR = 0
2 (Stereo)	1 (Mono)	output.M = 0.5 * (input.L + input.R)
2 (Stereo)	4 (Quad)	output.L = input.L output.R = input.R output.SL = 0 output.SR = 0
2 (Stereo)	6 (5.1)	output.L = input.L output.R = input.R output.C = 0 output.LFE = 0 output.SL = 0 output.SR = 0
4 (Quad)	1 (Mono)	output.M = 0.25 * (input.L + input.R + input.SL + input.SR)
4 (Quad)	2 (Stereo)	output.L = 0.5 * (input.L + input.SL) output.R = 0.5 * (input.R + input.SR)
4 (Quad)	6 (5.1)	output.L = input.L output.R = input.R output.C = 0 output.LFE = 0 output.SL = input.SL output.SR = input.SR
6 (5.1)	1 (Mono)	output.M = 0.7071 * (input.L + input.R) + input.C + 0.5 * (input.SL + input.SR)
6 (5.1)	2 (Stereo)	output.L = input.L + 0.7071 * (input.C + input.SL) output.R = input.R + 0.7071 * (input.C + input.SR)
6 (5.1)	4 (Quad)	output.L = input.L + 0.7071 * input.C output.R = input.R + 0.7071 * input.C output.SL = input.SL output.SR = input.SR

discrete

Number of input channels	Number of output channels	Mixing rules
x	y where y > x	Fill each output channel with its counterpart (channel with same number) the rest of output channels are silent channels
x	y where y < x	Fill each output channel with its counterpart (channel with same number) the rest of input channels are skipped