diff --git a/iiify/resolver.py b/iiify/resolver.py
index ee2c68c..616eba5 100644
--- a/iiify/resolver.py
+++ b/iiify/resolver.py
@@ -563,7 +563,7 @@ def addRendering(manifest, identifier, files):
                  "format": rendering['format']
                  })
 
-def addThumbnails(manifest, identifier, files):
+def addThumbnails(manifest, identifier, files, mediatype):
     """Creates thumbnails based on files.
 
     If the file appears to be a thumbnail (by format or name) attempt to create a IIIF thumbnail via Cantaloupe.
@@ -571,11 +571,11 @@ def addThumbnails(manifest, identifier, files):
     """
     thumbnail_files = []
     ia_thumb_files = []
-    
+
     for file in files:
         name = file.get("name", "")
         file_format = file.get("format", "")
-        
+
         if name == "__ia_thumb.jpg":
             ia_thumb_files.append(file)
         elif file_format in {"Thumbnail", "JPEG Thumb"}:
@@ -588,19 +588,29 @@ def addThumbnails(manifest, identifier, files):
     
     elif ia_thumb_files:
         files_to_process = ia_thumb_files
-    
+    av_types = ("audio", "movies", "etree")
     for file in files_to_process:
         name = file.get("name", "")
-        encoded_name = quote(name.replace('/', '%2f'))
-        # Forward solidus before thumbnail uri must always be %2f
-        iiif_url = f"{IMG_SRV}/2/{identifier.strip()}%2f{encoded_name}"
-        try:
-            manifest.create_thumbnail_from_iiif(iiif_url)
-        except requests.HTTPError:
-            print(f"Failed to generate thumbnail from Cantaloupe: {iiif_url}")
+        if mediatype in av_types:
             mimetype = "image/png" if name.endswith(".png") else "image/jpeg"
             static_url = f"{ARCHIVE}/download/{quote(identifier)}/{quote(name)}"
-            manifest.add_thumbnail(static_url, format=mimetype)
+            manifest.add_thumbnail(
+                static_url,
+                format=mimetype,
+                **({"width": file["width"]} if "width" in file else {"width": 192}),
+                **({"height": file["height"]} if "height" in file else {"height": 108})
+            )
+        else:
+            encoded_name = quote(name.replace('/', '%2f'))
+            # Forward solidus before thumbnail uri must always be %2f
+            iiif_url = f"{IMG_SRV}/2/{identifier.strip()}%2f{encoded_name}"
+            try:
+                manifest.create_thumbnail_from_iiif(iiif_url)
+            except requests.HTTPError:
+                print(f"Failed to generate thumbnail from Cantaloupe: {iiif_url}")
+                mimetype = "image/png" if name.endswith(".png") else "image/jpeg"
+                static_url = f"{ARCHIVE}/download/{quote(identifier)}/{quote(name)}"
+                manifest.add_thumbnail(static_url, format=mimetype)
     return
 
 def addPartOfCollection(resource, collections, domain=None):
@@ -673,7 +683,7 @@ def create_manifest3(identifier, domain=None, page=None):
     addMetadata(manifest, identifier, metadata['metadata'])
     addSeeAlso(manifest, identifier, metadata['files'])
     addRendering(manifest, identifier, metadata['files'])
-    addThumbnails(manifest, identifier, metadata['files'])
+    addThumbnails(manifest, identifier, metadata['files'], mediatype)
     addPartOfCollection(manifest, metadata.get('metadata').get('collection', []), domain)
 
     if mediatype == 'texts':
diff --git a/tests/test_manifests.py b/tests/test_manifests.py
index e8f5329..d8584c8 100644
--- a/tests/test_manifests.py
+++ b/tests/test_manifests.py
@@ -149,7 +149,7 @@ def test_encoded_thumb(self):
         self.assertEqual(resp.status_code, 200)
         manifest = resp.json
         self.assertEqual(len(manifest['thumbnail']),16, f"Expected 16 thumbnails, but got {len(manifest['thumbnail'])}")
-        self.assertEqual(manifest['thumbnail'][0]['id'],"https://iiif.archive.org/image/iiif/2/steamboat-willie-16mm-film-scan-4k-lossless%2fSteamboat%20Willie%20%5B16mm%20Film%20Scan%5D_ProRes%20%283400x2550%29.01_thumb.jpg/full/192,/0/default.jpg", f"Expected URL to be encoded")
+        self.assertEqual(manifest['thumbnail'][0]['id'],"https://archive.org/download/steamboat-willie-16mm-film-scan-4k-lossless/Steamboat%20Willie%20%5B16mm%20Film%20Scan%5D_ProRes%20%283400x2550%29.01_thumb.jpg", f"Expected URL to be encoded")
 
         self.assertEqual(len(manifest['items']),1, f"Expected 1 canvas, but got {len(manifest['items'])}")