audio(koala): add new audio filter KoalaFilter

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Added `KoalaFilter` which implement on device noise reduction using Koala
+  Noise Suppression.
+  (see https://picovoice.ai/platform/koala/)
+
 - Pipecat now supports Python 3.13. We had a dependency on the `audioop` package
   which was deprecated and now removed on Python 3.13. We are now using
   `audioop-lts` (https://github.com/AbstractUmbra/audioop) to provide the same

src/pipecat/audio/filters/koala_filter.py

@@ -0,0 +1,75 @@
+#
+# Copyright (c) 2024, Daily
+#
+# SPDX-License-Identifier: BSD 2-Clause License
+#
+
+from typing import Sequence
+
+import numpy as np
+from loguru import logger
+
+from pipecat.audio.filters.base_audio_filter import BaseAudioFilter
+from pipecat.frames.frames import FilterControlFrame, FilterEnableFrame
+
+try:
+    import pvkoala
+except ModuleNotFoundError as e:
+    logger.error(f"Exception: {e}")
+    logger.error("In order to use the Koala filter, you need to `pip install pipecat-ai[koala]`.")
+    raise Exception(f"Missing module: {e}")
+
+
+class KoalaFilter(BaseAudioFilter):
+    """This is an audio filter that uses Koala Noise Suppression (from
+    PicoVoice).
+
+    """
+
+    def __init__(self, *, access_key: str) -> None:
+        self._access_key = access_key
+
+        self._filtering = True
+        self._sample_rate = 0
+        self._koala = pvkoala.create(access_key=f"{self._access_key}")
+        self._koala_ready = True
+        self._audio_buffer = bytearray()
+
+    async def start(self, sample_rate: int):
+        self._sample_rate = sample_rate
+        if self._sample_rate != self._koala.sample_rate:
+            logger.warning(
+                f"Koala filter needs sample rate {self._koala.sample_rate} (got {self._sample_rate})"
+            )
+            self._koala_ready = False
+
+    async def stop(self):
+        self._koala.reset()
+
+    async def process_frame(self, frame: FilterControlFrame):
+        if isinstance(frame, FilterEnableFrame):
+            self._filtering = frame.enable
+
+    async def filter(self, audio: bytes) -> bytes:
+        if not self._koala_ready or not self._filtering:
+            return audio
+
+        self._audio_buffer.extend(audio)
+
+        filtered_data: Sequence[int] = []
+
+        num_frames = len(self._audio_buffer) // 2
+        while num_frames >= self._koala.frame_length:
+            # Grab the number of frames required by Koala.
+            num_bytes = self._koala.frame_length * 2
+            audio = bytes(self._audio_buffer[:num_bytes])
+            # Process audio
+            data = np.frombuffer(audio, dtype=np.int16).tolist()
+            filtered_data += self._koala.process(data)
+            # Adjust audio buffer and check again
+            self._audio_buffer = self._audio_buffer[num_bytes:]
+            num_frames = len(self._audio_buffer) // 2
+
+        filtered = np.array(filtered_data, dtype=np.int16).tobytes()
+
+        return filtered