diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index a927dcb..e04aa25 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -104,7 +104,7 @@
       <workItem from="1602850978698" duration="7902000" />
       <workItem from="1602908398925" duration="34104000" />
       <workItem from="1603714609431" duration="5637000" />
-      <workItem from="1603720261881" duration="4847000" />
+      <workItem from="1603720261881" duration="6236000" />
     </task>
     <task id="LOCAL-00001" summary="mp3 support! more helpful interface! better code! yahoo!!">
       <created>1602927759343</created>
@@ -176,7 +176,14 @@
       <option name="project" value="LOCAL" />
       <updated>1603723480563</updated>
     </task>
-    <option name="localTasksCounter" value="11" />
+    <task id="LOCAL-00011" summary="remove unneeded file extension">
+      <created>1603814270091</created>
+      <option name="number" value="00011" />
+      <option name="presentableId" value="LOCAL-00011" />
+      <option name="project" value="LOCAL" />
+      <updated>1603814270092</updated>
+    </task>
+    <option name="localTasksCounter" value="12" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -205,7 +212,8 @@
     <MESSAGE value="my py dot ini" />
     <MESSAGE value="added project files, aiff support" />
     <MESSAGE value="turns out i didn't need to do anything to add alac support - they work the same as aac m4a files do. although i did find and fix a bug in the m4a handling so that's good at least 0uo" />
-    <option name="LAST_COMMIT_MESSAGE" value="turns out i didn't need to do anything to add alac support - they work the same as aac m4a files do. although i did find and fix a bug in the m4a handling so that's good at least 0uo" />
+    <MESSAGE value="remove unneeded file extension" />
+    <option name="LAST_COMMIT_MESSAGE" value="remove unneeded file extension" />
   </component>
   <component name="WindowStateProjectService">
     <state x="555" y="188" width="800" height="672" key="#Deployment" timestamp="1602927147820">
diff --git a/bcao.py b/bcao.py
index cb9e471..e93c725 100755
--- a/bcao.py
+++ b/bcao.py
@@ -39,6 +39,15 @@ MutagenTags = Union[mutagen.id3.ID3Tags, mutagen.mp4.Tags, mutagen.oggvorbis.Ogg
 args: argparse.Namespace
 tmp_dir: tempfile.TemporaryDirectory # type: ignore
 
+format_lookup: Dict[str, str] = {
+	"mp3":  "id3",
+	"m4a":  "m4a",
+	"ogg":  "vorbis",
+	"flac": "vorbis",
+	"wav":  "id3",
+	"aiff": "id3"
+}
+
 class SongInfo:
 	tag_lookup: Dict[str, Dict[str, str]] = {
 		"track":        {"id3": "TRCK", "m4a": "trkn", "vorbis": "tracknumber"},
@@ -48,15 +57,6 @@ class SongInfo:
 		"album_artist": {"id3": "TPE2", "m4a": "aART", "vorbis": "albumartist"}
 	}
 
-	format_lookup: Dict[str, str] = {
-		"mp3":  "id3",
-		"m4a":  "m4a",
-		"ogg":  "vorbis",
-		"flac": "vorbis",
-		"wav":  "id3",
-		"aiff": "id3"
-	}
-
 	def __init__(self, file_name: Path):
 		self.m_file: MutagenFile = mutagen.File(file_name)
 		self.m_tags: MutagenTags = self.m_file.tags
@@ -65,6 +65,9 @@ class SongInfo:
 		self.format = path.splitext(file_name)[1][1:]
 		self.fallback = False
 
+		if self.format not in format_lookup:
+			raise ValueError(f"Unsupported file type: {self.format}")
+
 		fallbacks = re.match(
 			r"^(?P<artist>.+) - (?P<album>.+) - (?P<track>\d{2,}) (?P<title>.+)\.(?:ogg|flac|aiff|wav|mp3|m4a)$",
 			self.file_name
@@ -95,14 +98,14 @@ class SongInfo:
 
 			# write fallback tags to file
 			for standard_name, tag_set in self.tag_lookup.items():
-				tag = tag_set[self.format_lookup[self.format]]
+				tag = tag_set[format_lookup[self.format]]
 				self.m_tags[tag] = self.new_id3_tag(standard_name, self.tags[standard_name])
 
 			self.m_file.save()
 
 		else:
 			for standard_name, tag_set in self.tag_lookup.items():
-				tag = tag_set[self.format_lookup[self.format]]
+				tag = tag_set[format_lookup[self.format]]
 
 				if tag not in self.m_tags:
 					print(f"{tag} not in self.m_tags")
@@ -150,34 +153,35 @@ class SongInfo:
 		return f"{self.tags['track'].zfill(zeroes)} {self.tags['title']}.{self.format}"
 
 	def has_cover(self) -> bool:
-		if self.format == "ogg":
-			return "metadata_block_picture" in self.m_tags and len(self.m_tags["metadata_block_picture"]) != 0
-
 		if self.format == "flac":
+			# needs to be handled separately from ogg, as it doesn't use the vorbis tags for cover art for whatever reason
 			return len(self.m_file.pictures) != 0
 
-		if self.format in ["mp3", "wav", "aiff"]:
+		if format_lookup[self.format] == "vorbis":
+			return "metadata_block_picture" in self.m_tags and len(self.m_tags["metadata_block_picture"]) != 0
+
+		if format_lookup[self.format] == "id3":
 			apics: List[APIC] = self.m_tags.getall("APIC")
 			for apic in apics:
 				if apic.type == PictureType.COVER_FRONT:
 					return True
 			return False
 
-		if self.format == "m4a":
+		if format_lookup[self.format] == "m4a":
 			return 'covr' in self.m_tags and len(self.m_tags['covr']) != 0
 
 		raise NotImplementedError("Song format not yet implemented.")
 
 	def set_cover(self, to_embed: Union[Picture, APIC, MP4Cover]) -> None:
 		# embed cover art
-		if self.format == "ogg":
-			self.m_tags["metadata_block_picture"] = [b64encode(to_embed.write()).decode("ascii")]
-		elif self.format == "flac":
+		if self.format == "flac":
 			self.m_file.clear_pictures()
 			self.m_file.add_picture(to_embed)
-		elif self.format in ["mp3", "wav", "aiff"]:
+		elif format_lookup[self.format] == "vorbis":
+			self.m_tags["metadata_block_picture"] = [b64encode(to_embed.write()).decode("ascii")]
+		elif format_lookup[self.format] == "id3":
 			self.m_tags.add(to_embed)
-		elif self.format == "m4a":
+		elif format_lookup[self.format] == "m4a":
 			self.m_tags['covr'] = [to_embed]
 
 		self.m_file.save()
@@ -295,17 +299,17 @@ def main() -> None:
 
 		# it's really strange that the more annoying the file's metadata is, the *less* annoying it is to create cover art
 		#  for it in mutagen.
-		# vorbis: open standard, so easy to use that mutagen supplies a bunch of "easy" wrappers around other formats to
-		#  make them work more like mutagen.
+		# vorbis: open standard, so easy to use that mutagen supplies a bunch of "easy" wrappers around other tag formats to
+		#  make them work more like vorbis comments.
 		#  cover-annoy-o-meter: high. mutagen requires you to specify the width, height, colour depth, etc etc
-		# id3: well documented, but rather cryptic (which is more understandable, "album_artist" or "TPE2").
+		# id3: well documented, but rather cryptic (which is more understandable, "album_artist" or "TPE2"?).
 		#  cover-annoy-o-meter: not bad at all - at least you get a constructor this time - although it is kinda annoying
 		#  that you have to specify the file encoding, and how you need both a type and a desc.
 		# m4a: scarce documentation, closed format, half reverse engineered from whatever itunes is doing, exists pretty
 		#  much exclusively in the realm of apple stuff.
 		#  cover-annoy-o-meter: all you need is the file data and the format type.
 
-		if song_format in ["ogg", "flac"]:
+		if format_lookup[song_format] == "vorbis":
 			# i hate this
 			with Image.open(io.BytesIO(data)) as image:
 				embed_cover = Picture()
@@ -316,7 +320,7 @@ def main() -> None:
 				embed_cover.height = image.size[1]
 				embed_cover.depth = image.bits
 
-		elif song_format in ["mp3", "wav", "aiff"]:
+		elif format_lookup[song_format] == "id3":
 			# apparently APIC files get compressed on save if they are "large":
 			# https://mutagen.readthedocs.io/en/latest/api/id3_frames.html#mutagen.id3.APIC
 			# i don't know what that means (lossless text compression? automatic JPEG conversion?) and i don't know if or how
@@ -341,7 +345,7 @@ def main() -> None:
 				data=data
 			)
 
-		elif song_format == "m4a":
+		elif format_lookup[song_format] == "m4a":
 			embed_cover = MP4Cover(
 				data=data,
 				imageformat=MP4Cover.FORMAT_JPEG