[orf] re-introduce separate classes for ORF radios...

...to preserve ie_keys.

youtube_dl/extractor/extractors.py

@@ -680,7 +680,8 @@ from .openload import OpenloadIE
 from .ora import OraTVIE
 from .orf import (
     ORFTVthekIE,
-    ORFRadioIE,
+    ORFFM4IE,
+    ORFOE1IE,
     ORFIPTVIE,
 )
 from .pandatv import PandaTVIE

youtube_dl/extractor/orf.py

@@ -143,9 +143,6 @@ class ORFTVthekIE(InfoExtractor):
 
 
 class ORFRadioIE(InfoExtractor):
-    IE_NAME = 'orf:radio'
-    IE_DESC = 'ORF Radio'
-
     _VALID_URL = r'https?://(?P<station>oe1|fm4)\.orf\.at/(?:7tage/?#|player/)(?P<date>[0-9]+)/(?P<show>\w+)'
 
     _TESTS = [
@@ -214,6 +211,16 @@ class ORFRadioIE(InfoExtractor):
         }
 
 
+class ORFFM4IE(ORFRadioIE):
+    IE_NAME = 'orf:fm4'
+    IE_DESC = 'radio FM4'
+
+
+class ORFOE1IE(ORFRadioIE):
+    IE_NAME = 'orf:oe1'
+    IE_DESC = 'Radio Österreich 1'
+
+
 class ORFIPTVIE(InfoExtractor):
     IE_NAME = 'orf:iptv'
     IE_DESC = 'iptv.ORF.at'