init

lib_audio_dsp/python/audio_dsp/models/biquad.py

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+# Copyright 2025 XMOS LIMITED.
+# This Software is subject to the terms of the XMOS Public Licence: Version 1.
+"""Models for biquad filter stages."""
+
+from typing import Literal
+from pydantic import Field
+
+from audio_dsp.models.stage import StageModel, StageParameters
+from audio_dsp.models.fields import BIQUAD_TYPES, biquad_bypass
+
+
+class BiquadParameters(StageParameters):
+    """Parameters for a biquad filter.
+
+    Attributes
+    ----------
+    filter_type : audio_dsp.models.fields.BIQUAD_TYPES
+        The parameters of the type of biquad filter to use (e.g., biquad_lowpass, biquad_highpass, etc.)
+
+    """
+
+    filter_type: BIQUAD_TYPES = Field(
+        default=biquad_bypass(),
+        description="Type of biquad filter to implement and it's parameters.",
+    )
+
+
+class Biquad(StageModel):
+    """A single biquad filter stage.
+
+    A biquad filter is a second-order recursive filter that can implement various
+    filter types like lowpass, highpass, bandpass, etc. This stage implements a
+    single biquad section with slew rate limiting to prevent audio artifacts
+    when parameters are changed.
+    """
+
+    op_type: Literal["Biquad"] = "Biquad"
+    parameters: BiquadParameters = Field(
+        default_factory=lambda: BiquadParameters(filter_type=biquad_bypass())
+    )
+
+
+class BiquadSlewParameters(BiquadParameters):
+    """Parameters for a slewing biquad filter."""
+
+    slew_shift: int = Field(
+        default=6, ge=0, lt=31, description="The shift value used in the exponential slew."
+    )
+
+
+class BiquadSlew(StageModel):
+    """A single biquad filter stage.
+
+    A biquad filter is a second-order recursive filter that can implement various
+    filter types like lowpass, highpass, bandpass, etc. This stage implements a
+    single biquad section with slew rate limiting to prevent audio artifacts
+    when parameters are changed.
+    """
+
+    op_type: Literal["BiquadSlew"] = "BiquadSlew"
+    parameters: BiquadSlewParameters = Field(
+        default_factory=lambda: BiquadSlewParameters(filter_type=biquad_bypass())
+    )