This directory contains the Crossover filter component.

The Crossover splits an audio signal into multiple frequency bands (e.g., Low, Mid, High) so they can be processed or routed independently (like to a woofer and a tweeter).

graph LR
  In[Wideband Audio In] --> Cross[Crossover Split]
  Cross --> OutLow[Low Frequency Out]
  Cross --> OutHigh[High Frequency Out]

• Kconfig: Selects the Crossover Filter (COMP_CROSSOVER), which splits signals into driver-specific frequencies. Also automatically selects COMP_BLOB and MATH_IIR_DF2T math functions for its internal filters.
• CMakeLists.txt: Handles modular builds (llext). Selects crossover.c and generic implementations, and chooses the correct IPC file (crossover_ipc3.c or crossover_ipc4.c) based on the active IPC major version.
• crossover.toml: Topology parameters for the Crossover module. For IPC4, it sets init_config = 1 so that base_cfg_ext is appended to the IPC payload, which is required up-front to identify output pin indices. Defines UUID, pins, and memory requirements.
• Topology (.conf): tools/topology/topology2/include/components/crossover.conf defines the crossover widget object. It sets basic widget requirements and defaults to type effect with UUID d1:9a:8c:94:6a:80:31:41:ad:6c:b2:bd:a9:e3:5a:9f.
• MATLAB Tuning (tune/): The tune directory holds MATLAB/Octave scripts (like sof_example_crossover.m) that convert mathematical frequency split parameters (e.g., 200 Hz, 1000 Hz, 3000 Hz cutoffs) into binary, ALSA, and .conf payloads suitable for 2-way, 3-way, or 4-way driver crossover configurations.