feat: add Mfcc skeleton

src/apollon/signal/cepstral.py

@@ -0,0 +1,29 @@
+"""
+Spectral transforms
+====================
+"""
+
+from typing import Self
+
+import numpy as np
+from pydantic import BaseModel
+
+from .filter import triang_filter_bank
+from .spectral import Dft, Stft
+
+
+class TriagFilterSpec(BaseModel):
+    low: float
+    high: float
+    n_filters: int
+
+
+class Mfcc:
+
+    @classmethod
+    def from_stft(cls, stft: Stft, spec: TriangFilterSpec) -> Self:
+        pass
+
+    @classmethod
+    def from_dft(cls, dft: Dft, spec: TriangFilterSpec) -> Self:
+        pass