diff --git a/test/test_InfoExtractor.py b/test/test_InfoExtractor.py
index f18a823fcf..686c63efac 100644
--- a/test/test_InfoExtractor.py
+++ b/test/test_InfoExtractor.py
@@ -574,6 +574,32 @@ def test_parse_mpd_formats(self):
                 self.ie._sort_formats(formats)
                 expect_value(self, formats, expected_formats, None)
 
+    def test_parse_f4m_formats(self):
+        _TEST_CASES = [
+            (
+                # https://github.com/rg3/youtube-dl/issues/14660
+                'custom_base_url',
+                'http://api.new.livestream.com/accounts/6115179/events/6764928/videos/144884262.f4m',
+                [{
+                    'manifest_url': 'http://api.new.livestream.com/accounts/6115179/events/6764928/videos/144884262.f4m',
+                    'ext': 'flv',
+                    'format_id': '2148',
+                    'protocol': 'f4m',
+                    'tbr': 2148,
+                    'width': 1280,
+                    'height': 720,
+                }]
+            ),
+        ]
+
+        for f4m_file, f4m_url, expected_formats in _TEST_CASES:
+            with io.open('./test/testdata/f4m/%s.f4m' % f4m_file,
+                         mode='r', encoding='utf-8') as f:
+                formats = self.ie._parse_f4m_formats(
+                    compat_etree_fromstring(f.read().encode('utf-8')),
+                    f4m_url, None)
+                self.ie._sort_formats(formats)
+                expect_value(self, formats, expected_formats, None)
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/test/testdata/f4m/custom_base_url.f4m b/test/testdata/f4m/custom_base_url.f4m
new file mode 100644
index 0000000000..74e1539e88
--- /dev/null
+++ b/test/testdata/f4m/custom_base_url.f4m
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<manifest xmlns="http://ns.adobe.com/f4m/1.0">
+    <streamType>recorded</streamType>
+    <baseURL>http://vod.livestream.com/events/0000000000673980/</baseURL>
+    <duration>269.293</duration>
+    <bootstrapInfo profile="named" id="bootstrap_1">AAAAm2Fic3QAAAAAAAAAAQAAAAPoAAAAAAAEG+0AAAAAAAAAAAAAAAAAAQAAABlhc3J0AAAAAAAAAAABAAAAAQAAAC4BAAAAVmFmcnQAAAAAAAAD6AAAAAAEAAAAAQAAAAAAAAAAAAAXcAAAAC0AAAAAAAQHQAAAE5UAAAAuAAAAAAAEGtUAAAEYAAAAAAAAAAAAAAAAAAAAAAA=</bootstrapInfo>
+    <media url="b90f532f-b0f6-4f4e-8289-706d490b2fd8_2292" bootstrapInfoId="bootstrap_1" bitrate="2148" width="1280" height="720" videoCodec="avc1.4d401f" audioCodec="mp4a.40.2">
+        <metadata>AgAKb25NZXRhRGF0YQgAAAAIAAhkdXJhdGlvbgBAcNSwIMSbpgAFd2lkdGgAQJQAAAAAAAAABmhlaWdodABAhoAAAAAAAAAJZnJhbWVyYXRlAEA4/7DoLwW3AA12aWRlb2RhdGFyYXRlAECe1DLgjcobAAx2aWRlb2NvZGVjaWQAQBwAAAAAAAAADWF1ZGlvZGF0YXJhdGUAQGSimlvaPKQADGF1ZGlvY29kZWNpZABAJAAAAAAAAAAACQ==</metadata>
+    </media>
+</manifest>