new structure for transcription engine

- found problems with mps
- integrated jinja2 templates for rendering (.tex?)
- raw ui & bad structure

transcription/preprocessing/audio_preprocessor.py

@@ -0,0 +1,35 @@
+from transcription.audio import Audio
+import torchaudio
+
+class AudioPreprocessor:
+    TARGET_SAMPLING_RATE: int = 16000
+
+    # for different models in future
+    # def __init__(self, model):
+    #     pass
+
+    def _resample(
+        self,
+        audio: Audio
+    ) -> None:
+        if audio.sr != self.TARGET_SAMPLING_RATE:
+            audio.waveform = torchaudio.functional.resample(
+                audio.waveform, 
+                audio.sr, 
+                self.TARGET_SAMPLING_RATE
+            )
+    
+    def _to_mono(
+        self,
+        audio: Audio
+    ) -> None:
+        if audio.waveform.shape[0] > 1:
+            audio.waveform = audio.waveform.mean(dim=0, keepdim=True)
+        audio.waveform = audio.waveform.squeeze(0)
+    
+    def prepare(
+        self, 
+        audio: Audio
+    ):
+        self._resample(audio)
+        self._to_mono(audio)