[Bugfix] Handle libsndfile sf_error(NULL) race condition in audio fallback (#37782)

Signed-off-by: Andreas Karatzas <akaratza@amd.com>

vllm/multimodal/media/audio.py

@@ -34,10 +34,14 @@ except ImportError:
 # Public libsndfile error codes exposed via `soundfile.LibsndfileError.code`, soundfile
 # being librosa's main backend. Used to validate if an audio loading error is due to a
 # server error vs a client error (invalid audio file).
+# 0 = sf_error(NULL) race condition: when multiple threads fail sf_open_virtual
+#     concurrently, one thread may clear the global error before another reads it,
+#     producing code=0 ("Garbled error message from libsndfile" in soundfile).
+#     See: https://github.com/bastibe/python-soundfile/issues/479
 # 1 = unrecognised format      (file is not a supported audio container)
 # 3 = malformed file           (corrupt or structurally invalid audio)
 # 4 = unsupported encoding     (codec not supported by this libsndfile build)
-_BAD_SF_CODES = {1, 3, 4}
+_BAD_SF_CODES = {0, 1, 3, 4}
 
 
 def load_audio_pyav(