Tweaks (#24067)

* improve keyframes messages

* don't pad the labelmap with unknown

`load_labels()` prefilled 91 `unknown` entries before reading the label file, so any model with fewer than 91 classes kept that padding in `merged_labelmap` and `unknown` showed up as a selectable object type in the objects settings UI. The padding only existed so `RemoteObjectDetector.detect` could index the labelmap without a KeyError, and it didn't even cover the empty-file case or Frigate+, which never had a prefill. Both lookups now skip class ids the labelmap doesn't name and warn once per id.

frigate/util/builtin.py

@@ -152,12 +152,19 @@ def get_record_segment_time(config: "CameraConfig") -> int:
 
 
 def load_labels(
-    path: str | None, encoding="utf-8", prefill=91, indexed: bool | None = None
+    path: str | None, encoding="utf-8", prefill=0, indexed: bool | None = None
 ):
     """Loads labels from file (with or without index numbers).
+
+    Only the indices the file defines are returned, so the result describes
+    exactly the classes a model can name. Callers must treat a missing index
+    as an unnamed class rather than assuming a contiguous range.
+
     Args:
       path: path to label file.
       encoding: label file encoding.
+      prefill: pad indices below this with "unknown" before reading the file.
+      indexed: whether lines start with an index; auto-detected when None.
     Returns:
       Dictionary mapping indices to labels.
     """

frigate/util/services.py

@@ -1061,6 +1061,7 @@ def ffprobe_stream(ffmpeg, path: str, detailed: bool = False) -> sp.CompletedPro
 
 KEYFRAME_PROBE_WINDOW_SECONDS = 20
 KEYFRAME_GAP_WARNING_SECONDS = 4.0
+KEYFRAME_GAP_JITTER_SECONDS = 0.5
 
 
 def parse_keyframe_packets(output: str) -> tuple[list[float], float | None]:
@@ -1100,6 +1101,10 @@ def classify_keyframe_gaps(
       - "error" when the longest gap exceeds the record segment length
       - "warning" when the longest gap exceeds the warning threshold
       - "ok" otherwise
+
+    The "pattern" key separates the two causes so callers can give accurate
+    advice: "fixed" is a regular GOP that is simply too long, "variable" is
+    the irregular spacing a smart/+ codec produces.
     """
     thresholds = {
         "warning": KEYFRAME_GAP_WARNING_SECONDS,
@@ -1112,6 +1117,7 @@ def classify_keyframe_gaps(
             "max_gap": None,
             "mean_gap": None,
             "min_gap": None,
+            "pattern": None,
             "segment_time": segment_time,
             "severity": "unknown",
             "thresholds": thresholds,
@@ -1119,6 +1125,7 @@ def classify_keyframe_gaps(
 
     gaps = [b - a for a, b in zip(keyframe_pts, keyframe_pts[1:])]
     max_gap = max(gaps)
+    min_gap = min(gaps)
 
     if max_gap > segment_time:
         severity = "error"
@@ -1127,11 +1134,16 @@ def classify_keyframe_gaps(
     else:
         severity = "ok"
 
+    # allow for encoder jitter and probe rounding before calling a GOP variable
+    tolerance = max(KEYFRAME_GAP_JITTER_SECONDS, min_gap * 0.25)
+    pattern = "variable" if (max_gap - min_gap) > tolerance else "fixed"
+
     return {
         "keyframe_count": len(keyframe_pts),
         "max_gap": round(max_gap, 2),
         "mean_gap": round(sum(gaps) / len(gaps), 2),
-        "min_gap": round(min(gaps), 2),
+        "min_gap": round(min_gap, 2),
+        "pattern": pattern,
         "segment_time": segment_time,
         "severity": severity,
         "thresholds": thresholds,