Mixer & Sends

17 tools for mixing, routing, and send/return topology.

Mixing (5)

Tool	Description
get_mixer_state	Full mixer state — all AUs with volume, panning, mute, solo, type
set_track_mute	Mute or unmute an audio unit
set_track_panning	Set panning of an AU. -1.0 = full left, 0.0 = center, 1.0 = full right
set_track_solo	Solo or unsolo an audio unit
set_track_volume	Set volume of an AU in dB

Volume convention

Volume is in dB, mapped via a power curve:

• 0.0 → unity (0 dB)
• -1.0 → -∞ dB (silent)
• +1.0 → +6 dB

Use set_track_volume(unit_index, volume_db) — takes dB directly.

Sends & Buses (12)

Tool	Description
create_audio_bus	Create a new audio bus (aux bus) with its own AU and track
create_send	Create a parallel FX send bus from an audio unit
list_audio_buses	List all audio buses (primary output + FX buses)
list_sends	List all aux sends on an audio unit
remove_audio_bus	Remove an FX audio bus and its associated AU
remove_send	Remove an aux send from an audio unit
set_bus_color	Set the color (hue 0-360) of an audio bus
set_bus_enabled	Enable or mute an audio bus (FX bus A/B comparison)
set_bus_label	Set the label (name) of an audio bus
set_send_level	Set the send level for an existing aux send
set_send_pan	Set stereo pan for an aux send (-1.0 to 1.0)
set_send_routing	Set routing mode (pre-fader or post-fader)

Send topology

graph LR
    A[Source AU] -->|post-fader send| B[FX Bus]
    B --> C[FX Unit<br/>e.g. Reverb]
    C --> D[Primary Bus<br/>main output]
    A -->|direct| D

• Source AU sends a portion of its signal to an FX Bus
• FX Bus has its own AU with effects (e.g. reverb, delay)
• FX Bus output goes to the Primary Bus (main output)
• Send level controls how much signal is sent
• Pre-fader = send level independent of track volume
• Post-fader = send level follows track volume

Example: reverb send

# Create a reverb bus
bus = await server.mcp_opendaw_create_audio_bus(label="Reverb Bus")
bus_index = bus["bus_index"]

# Send from vocal AU to reverb bus
await server.mcp_opendaw_create_send(unit_index=0, bus_index=bus_index)

# Set send level
await server.mcp_opendaw_set_send_level(unit_index=0, send_index=0, level=0.4)

# Add reverb on the bus
await server.mcp_opendaw_add_effect(unit_index=bus_index, effect_type="Dattorro")
await server.mcp_opendaw_set_effect_parameter(
    unit_index=bus_index, effect_index=0, param="decay", value=0.7
)