[arcalive] extend 'gifs' option

use fallback URLs by default

docs/configuration.rst

@@ -1408,12 +1408,22 @@ Description
 extractor.arcalive.gifs
 -----------------------
 Type
-    ``bool``
+    * ``bool``
+    * ``string``
 Default
     ``true``
 Description
-    Check if ``.mp4`` videos have a ``.gif`` version
-    and download those instead.
+    Try to download ``.gif`` versions of ``.mp4`` videos.
+
+    ``true`` | ``"fallback``
+        Use the ``.gif`` version as primary URL
+        and provide the ``.mp4`` one as
+        `fallback <extractor.*.fallback_>`__.
+    ``"check"``
+        Check whether a ``.gif`` version is available
+        by sending an extra HEAD request.
+    ``false``
+        Always download the ``.mp4`` version.
 
 
 extractor.artstation.external

gallery_dl/extractor/arcalive.py

@@ -41,7 +41,9 @@ class ArcalivePostExtractor(ArcaliveExtractor):
 
     def items(self):
         self.emoticons = self.config("emoticons", False)
-        self.gifs = self.config("gifs", True)
+        self.gifs = gifs = self.config("gifs", True)
+        if gifs:
+            self.gifs_fallback = (gifs != "check")
 
         post = self.api.post(self.groups[0])
         files = self._extract_files(post)
@@ -90,11 +92,15 @@ class ArcalivePostExtractor(ArcaliveExtractor):
                     url = path + "." + orig
             elif video and self.gifs:
                 url_gif = url.rpartition(".")[0] + ".gif"
-                response = self.request(
-                    url_gif + "?type=orig", method="HEAD", fatal=False)
-                if response.status_code < 400:
+                if self.gifs_fallback:
                     fallback = (url + "?type=orig",)
                     url = url_gif
+                else:
+                    response = self.request(
+                        url_gif + "?type=orig", method="HEAD", fatal=False)
+                    if response.status_code < 400:
+                        fallback = (url + "?type=orig",)
+                        url = url_gif
 
             files.append({
                 "url"   : url + "?type=orig",

test/results/arcalive.py

@@ -88,6 +88,7 @@ __tests__ = (
     "#url"    : "https://arca.live/b/bluearchive/117240135",
     "#comment": ".mp4 video",
     "#class"  : arcalive.ArcalivePostExtractor,
+    "#options": {"gifs": "check"},
     "#urls"   : "https://ac.namu.la/20240926sac/16f07778a97f91b935c8a3394ead01a223d96b2a619fdb25c4628ddba88b5fad.mp4?type=orig",
 },
 
@@ -95,7 +96,18 @@ __tests__ = (
     "#url"    : "https://arca.live/b/bluearchive/111191955",
     "#comment": "fake .mp4 GIF",
     "#class"  : arcalive.ArcalivePostExtractor,
+    "#options": {"gifs": True},
     "#urls"   : "https://ac.namu.la/20240714sac/c8fcadeb0b578e5121eb7a7e8fb05984cb87c68e7a6e0481a1c8869bf0ecfd2b.gif?type=orig",
+
+    "_fallback": ("https://ac.namu.la/20240714sac/c8fcadeb0b578e5121eb7a7e8fb05984cb87c68e7a6e0481a1c8869bf0ecfd2b.mp4?type=orig",),
+},
+
+{
+    "#url"    : "https://arca.live/b/bluearchive/111191955",
+    "#comment": "fake .mp4 GIF",
+    "#class"  : arcalive.ArcalivePostExtractor,
+    "#options": {"gifs": False},
+    "#urls"   : "https://ac.namu.la/20240714sac/c8fcadeb0b578e5121eb7a7e8fb05984cb87c68e7a6e0481a1c8869bf0ecfd2b.mp4?type=orig",
 },
 
 {