Fix .m4a support in some setups (possibly for other formats not suppo…

…rted by libsndfile) (#1427)

* LibsndfileBackend: Exclude mp4/m4a/m4b files from set of files it is applicable to

* AudioreadBackend: supports_info=True

* shar export: fix exception printing

* AudioreadBackend: black formatting

lhotse/audio/backend.py

@@ -516,6 +516,10 @@ def handles_special_case(self, path_or_fd: Union[Pathlike, FileObject]) -> bool:
         return False
 
     def is_applicable(self, path_or_fd: Union[Pathlike, FileObject]) -> bool:
+        if isinstance(path_or_fd, (Path, str)) and any(
+            str(path_or_fd).endswith(ext) for ext in [".mp4", ".m4a", ".m4b"]
+        ):
+            return False
         return True
 
     def supports_save(self) -> bool:
@@ -571,6 +575,9 @@ def read_audio(
             duration=duration,
         )
 
+    def supports_info(self):
+        return True
+
     def info(
         self,
         path_or_fd: Union[Pathlike, FileObject],

lhotse/cut/set.py

@@ -3570,7 +3570,7 @@ def _export_to_shar_single(
             except Exception as e:
                 if fault_tolerant:
                     logging.warning(
-                        "Skipping: failed to load cut '{cut.id}'. Error message: {e}."
+                        f"Skipping: failed to load cut '{cut.id}'. Error message: {e}."
                     )
                 else:
                     raise