Router

Overview

Channel routing without smoothing

Discussion

The router_module.m is an intelligent copier and combines several channels from different wires into a new multichannel wire.  The module can have multiple input pins but only a single output pin.  At instantiation time, you specify the number of input pins and number of output channels.

M = router_module(NAME, NUMINPIN, NUMOUTCHANNEL)

The module has an internal array channelIndex[] of integer values.  The array has length NUMOUTCHANNEL values and value N specifies the mapping from input pin and channel to output channel N.  Keep in mind that all indexes (both for pins and channels) are zero based.

The channelIndex integer is a packed 32-bit value

channelIndex = (pinIndex << 16) + (channelIndex)

or alternatively

channelIndex = 65536 * pinIndex + channelIndex.

If channelIndex is incorrectly set and the encoded pinIndex or channelIndex are out of range then the module will mute the corresponding channel.  The Router module performs a straight copy of data and supports all 32-bit data types.  The Router module is ideal for fixed routing configurations.  If you want to make changes to the routing table at run-time, you should use the smoothly varying RouterSmoothed and RouterSmoothedFract32 modules.

The module’s use will become clear through several examples.

Example #1 — Selecting a single channel

This is wasteful because it requires 3 modules to do what a single router module can do.  Create a Router with 1 input pin and 1 output channel.

The desired left output channel is on pin 0 and channel 0 so set .channelIndex to 65536 * 0 + 0 = 0.

The system only requires a single Router module now:

If instead you want to pass the right channel, set channelIndex to 65536*0 + 1 = 1. The string shown on the canvas will update showing you the specified channel ordering:

Example #2 — Selecting 2 channels

Suppose you have a 5.1 signal with channels ordered:  L, C, R, Ls, Rs, LFE.  If you want to form a new stereo signal with just the L and R channels, use a router with a single input pin and 2 output channels.  Then set the channelIndex values to:

channelIndex[0] = 65536 * 0 + 0 = 0

channelIndex[1] = 65536 * 0 + 2 = 2

If instead you want to extract the Ls and Rs signals, use:

channelIndex[0] = 65536 * 0 + 3 = 3

channelIndex[1] = 65536 * 0 + 4 = 4

Example #3 — Swapping left and right channels

The output channels do now have to be in the same order as the inputs.  For example, suppose you had a stereo signal and you want to swap the order of the left and right channels.  Create the Router module with 1 input pin and 2 output channels.  Then set:

channelIndex[0] = 65536 * 0 + 1 = 1

channelIndex[1] = 65536 * 0 + 0 = 0

Example #4 — Deleting a channel

Suppose you have a 5.1 signal with channels ordered:  L, R, C, LFE, Ls, Rs.  If you want to form a new 5 channel signal that excludes the LFE channel you would use a Router module with 1 input pin and 5 output channels.  Then set the channelIndex array to:

channelIndex[0] = 65536 * 0 + 0 = 0             // L

channelIndex[1] = 65536 * 0 + 1 = 1             // R

channelIndex[2] = 65536 * 0 + 2 = 2             // C

channelIndex[3] = 65536 * 0 + 4 = 4             // Ls

channelIndex[4] = 65536 * 0 + 5 = 5             // Rs

Example #5 — Inserting a channel

Let’s continue the previous example.  Suppose that you processed the LFE channel separately and now want to combine the 5 channel signal (L, R, C, Ls, Rs) with a separate LFE and form the signal (L, R, C, LFE, Ls, Rs).  You could do this with a Router module.  Configure the Router so that it has 2 input pins and 6 output channels.  The first input pin attaches to the 5 channel signal and the 2^nd output pin attaches to the LFE.  The channelIndex array is then configured as:

channelIndex[0] = 65536 * 0 + 0 = 0             // L

channelIndex[1] = 65536 * 0 + 1 = 1             // R

channelIndex[2] = 65536 * 0 + 2 = 2             // C

channelIndex[3] = 65536 * 1 + 0 = 65536     // LFE

channelIndex[4] = 65536 * 0 + 4 = 4             // Ls

channelIndex[5] = 65536 * 0 + 5 = 5             // Rs

Type Definition

typedef struct _ModuleRouter
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32* channelIndex;                          // Specifies input to output channel routing. Each item in the array corresponds to an output channel and contains two packed values: input pin number in the high 16 bits; input channel number in the low 16 bits.
} ModuleRouterClass;

Variables

Properties

Pins

Input Pins

Name: in1

Description: Input signal

Data type: {float, int, fract32}

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real and Complex

Output Pins

Name: out

Description: Output signal

Data type: {float, int, fract32}

MATLAB Usage

File Name: router_module.m

 M=router_module(NAME, NUMINPIN, NUMOUTCHANNEL)
 Creates a router module for use in the Audio Weaver environment, which
 selects channels from multiple input pins and combines them into a single
 multichannel output.  
 
 Arguments:
    NAME - name of the module.
    NUMINPIN - number of input pins.
    NUMOUTCHANNEL - number of interleaved outputs. There is a single
         output pin.