From 39a33f6143f4a95080e39fdf6e19dbb1d2b5e22a Mon Sep 17 00:00:00 2001
From: JP Verdejo <jpverdejo@gmail.com>
Date: Mon, 26 Jun 2023 19:33:11 +0000
Subject: [PATCH] Expose dBFS when doing audio analysis

---
 frigate/app.py          |  1 +
 frigate/events/audio.py | 15 ++++++++++++++-
 frigate/http.py         | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/frigate/app.py b/frigate/app.py
index 15fb2ff69..ff948b2e6 100644
--- a/frigate/app.py
+++ b/frigate/app.py
@@ -259,6 +259,7 @@ class FrigateApp:
             self.onvif_controller,
             self.external_event_processor,
             self.plus_api,
+            self.dispatcher,
         )
 
     def init_onvif(self) -> None:
diff --git a/frigate/events/audio.py b/frigate/events/audio.py
index 68491b8a6..8df0e4209 100644
--- a/frigate/events/audio.py
+++ b/frigate/events/audio.py
@@ -167,9 +167,22 @@ class AudioEventMaintainer(threading.Thread):
         if not self.feature_metrics[self.config.name]["audio_enabled"].value:
             return
 
-        waveform = (audio / AUDIO_MAX_BIT_RANGE).astype(np.float32)
+        audio_as_float = audio.astype(np.float32)
+        waveform = audio_as_float / AUDIO_MAX_BIT_RANGE
         model_detections = self.detector.detect(waveform)
 
+        # Calculate RMS (Root-Mean-Square) which represents the average signal amplitude
+        # Note: np.float32 isn't serializable, we must use np.float64 to publish the message
+        rms = np.sqrt(np.mean(np.absolute(audio_as_float**2))).astype(np.float64)
+
+        # Transform RMS to dBFS (decibels relative to full scale)
+        dBFS = 20 * np.log10(np.abs(rms) / AUDIO_MAX_BIT_RANGE)
+
+        requests.post(
+            f"http://127.0.0.1:5000/api/{self.config.name}/metadata",
+            json={"dBFS": dBFS, "rms": rms},
+        )
+
         for label, score, _ in model_detections:
             if label not in self.config.audio.listen:
                 continue
diff --git a/frigate/http.py b/frigate/http.py
index 127b5defe..570d9bf13 100644
--- a/frigate/http.py
+++ b/frigate/http.py
@@ -28,6 +28,7 @@ from peewee import DoesNotExist, SqliteDatabase, fn, operator
 from playhouse.shortcuts import model_to_dict
 from tzlocal import get_localzone_name
 
+from frigate.comms.dispatcher import Dispatcher
 from frigate.config import FrigateConfig
 from frigate.const import CLIPS_DIR, MAX_SEGMENT_DURATION, RECORD_DIR
 from frigate.events.external import ExternalEventProcessor
@@ -61,6 +62,7 @@ def create_app(
     onvif: OnvifController,
     external_processor: ExternalEventProcessor,
     plus_api: PlusApi,
+    dispatcher: Dispatcher,
 ):
     app = Flask(__name__)
 
@@ -81,6 +83,7 @@ def create_app(
     app.onvif = onvif
     app.external_processor = external_processor
     app.plus_api = plus_api
+    app.dispatcher = dispatcher
     app.camera_error_image = None
     app.hwaccel_errors = []
 
@@ -1396,6 +1399,38 @@ def recording_clip(camera_name, start_ts, end_ts):
     return response
 
 
+@bp.route("/<camera_name>/metadata", methods=["POST"])
+def create_metadata_message(camera_name):
+    if not camera_name or not current_app.frigate_config.cameras.get(camera_name):
+        return jsonify(
+            {"success": False, "message": f"{camera_name} is not a valid camera."}, 404
+        )
+
+    request_json = request.get_json(silent=True)
+    if request_json == {}:
+        return jsonify(
+            {"success": False, "message": "Metadata json cannot be empty."}, 404
+        )
+
+    try:
+        current_app.dispatcher.publish(
+            "metadata", json.dumps(request_json), retain=False
+        )
+    except Exception as e:
+        logger.error(f"The error is {e}")
+        return jsonify(
+            {"success": False, "message": f"An unknown error occurred: {e}"}, 404
+        )
+
+    return jsonify(
+        {
+            "success": True,
+            "message": "Successfully published metadata message.",
+        },
+        200,
+    )
+
+
 @bp.route("/vod/<camera_name>/start/<int:start_ts>/end/<int:end_ts>")
 @bp.route("/vod/<camera_name>/start/<float:start_ts>/end/<float:end_ts>")
 def vod_ts(camera_name, start_ts, end_ts):