Migrate video

video/tts/mux.py

@@ -38,8 +38,20 @@ def measure_loudness(cmd_head: list[str], filter_complex: str) -> dict[str, str]
 
     Returns the measured values for the linear second pass, or None if the
     measurement failed (in which case the caller falls back to one-pass).
+
+    loudnorm prints its JSON summary at ffmpeg's `info` level, so this pass
+    cannot inherit the caller's `-loglevel warning`: that suppressed the very
+    stats parsed below, the probe returned None every single time, and every
+    render silently took the one-pass fallback the docstring treats as the
+    exception. Nothing surfaced it because the fallback sounds fine until you
+    compare it: one-pass is the dynamic mode, which pumps on speech.
     """
-    probe_cmd = cmd_head + [
+    probe_head = list(cmd_head)
+    if "-loglevel" in probe_head:
+        probe_head[probe_head.index("-loglevel") + 1] = "info"
+    else:
+        probe_head[1:1] = ["-loglevel", "info"]
+    probe_cmd = probe_head + [
         "-filter_complex",
         f"{filter_complex};[aout]loudnorm={LOUDNORM_TARGET}:print_format=json[anorm]",
         "-map",