[Callin] Add new extractor
diff --git a/youtube_dl/extractor/callin.py b/youtube_dl/extractor/callin.py
new file mode 100644
index 00000000000..341be479f1d
--- /dev/null
+++ b/youtube_dl/extractor/callin.py
@@ -0,0 +1,74 @@
+# coding: utf-8
+from __future__ import unicode_literals
+
+from .common import InfoExtractor
+from ..compat import compat_str
+from ..utils import (
+    ExtractorError,
+    traverse_obj,
+    try_get,
+)
+
+
+class CallinIE(InfoExtractor):
+    _VALID_URL = r'https?://(?:www\.)?callin\.com/episode/(?:[^/#?-]+-)*(?P<id>[^/#?-]+)'
+    _TESTS = [{
+        'url': 'https://www.callin.com/episode/fcc-commissioner-brendan-carr-on-elons-PrumRdSQJW',
+        'md5': '14ede27ee2c957b7e4db93140fc0745c',
+        'info_dict': {
+            'id': 'PrumRdSQJW',
+            'ext': 'mp4',
+            'title': 'FCC Commissioner Brendan Carr on Elon’s Starlink',
+            'description': 'Or, why the government doesn’t like SpaceX',
+            'channel': 'The Pull Request',
+            'channel_url': 'https://callin.com/show/the-pull-request-ucnDJmEKAa',
+        }
+    }, {
+        'url': 'https://www.callin.com/episode/episode-81-elites-melt-down-over-student-debt-lzxMidUnjA',
+        'md5': '16f704ddbf82a27e3930533b12062f07',
+        'info_dict': {
+            'id': 'lzxMidUnjA',
+            'ext': 'mp4',
+            'title': 'Episode 81- Elites MELT DOWN over Student Debt Victory? Rumble in NYC?',
+            'description': 'Let’s talk todays episode about the primary election shake up in NYC and the elites melting down over student debt cancelation.',
+            'channel': 'The DEBRIEF With Briahna Joy Gray',
+            'channel_url': 'https://callin.com/show/the-debrief-with-briahna-joy-gray-siiFDzGegm',
+        }
+    }]
+
+    def _search_nextjs_data(self, webpage, video_id, transform_source=None, fatal=True, **kw):
+        return self._parse_json(
+            self._search_regex(
+                r'(?s)<script[^>]+id=[\'"]__NEXT_DATA__[\'"][^>]*>([^<]+)</script>',
+                webpage, 'next.js data', fatal=fatal, **kw),
+            video_id, transform_source=transform_source, fatal=fatal)
+
+    def _real_extract(self, url):
+        video_id = self._match_id(url)
+        webpage = self._download_webpage(url, video_id)
+
+        next_data = self._search_nextjs_data(webpage, video_id)
+        episode = traverse_obj(next_data, ('props', 'pageProps', 'episode'), expected_type=dict)
+        if not episode:
+            raise ExtractorError('Failed to find episode data')
+
+        title = episode.get('title') or self._og_search_title(webpage)
+        description = episode.get('description') or self._og_search_description(webpage)
+
+        formats = []
+        formats.extend(self._extract_m3u8_formats(
+            episode.get('m3u8'), video_id, 'mp4',
+            entry_protocol='m3u8_native', fatal=False))
+        self._sort_formats(formats)
+
+        channel = try_get(episode, lambda x: x['show']['title'], compat_str)
+        channel_url = try_get(episode, lambda x: x['show']['linkObj']['resourceUrl'], compat_str)
+
+        return {
+            'id': video_id,
+            'title': title,
+            'description': description,
+            'formats': formats,
+            'channel': channel,
+            'channel_url': channel_url,
+        }
diff --git a/youtube_dl/extractor/extractors.py b/youtube_dl/extractor/extractors.py
index 947cbe8fdb4..f9e40d19f84 100644
--- a/youtube_dl/extractor/extractors.py
+++ b/youtube_dl/extractor/extractors.py
@@ -158,6 +158,7 @@
 from .buzzfeed import BuzzFeedIE
 from .byutv import BYUtvIE
 from .c56 import C56IE
+from .callin import CallinIE
 from .camdemy import (
     CamdemyIE,
     CamdemyFolderIE

## Please follow the guide below

- You will be asked some questions, please read them **carefully** and answer honestly
- Put an `x` into all the boxes [ ] relevant to your *pull request* (like that [x])
- Use *Preview* tab to see how your *pull request* will actually look like

---

### Before submitting a *pull request* make sure you have:
- [x] [Searched](https://github.com/ytdl-org/youtube-dl/search?q=is%3Apr&type=Issues) the bugtracker for similar pull requests
- [x] Read [adding new extractor tutorial](https://github.com/ytdl-org/youtube-dl#adding-support-for-a-new-site)
- [x] Read [youtube-dl coding conventions](https://github.com/ytdl-org/youtube-dl#youtube-dl-coding-conventions) and adjusted the code to meet them
- [x] Covered the code with tests (note that PRs without tests will be REJECTED)
- [x] Checked the code with [flake8](https://pypi.python.org/pypi/flake8)

### In order to be accepted and merged into youtube-dl each piece of code must be in public domain or released under [Unlicense](http://unlicense.org/). Check one of the following options:
- [x] I am the original author of this code and I am willing to release it under [Unlicense](http://unlicense.org/)
- [ ] I am not the original author of this code but it is in public domain or released under [Unlicense](http://unlicense.org/) (provide reliable evidence)

### What is the purpose of your *pull request*?
- [ ] Bug fix
- [ ] Improvement
- [x] New extractor
- [ ] New feature

---

### Description of your *pull request* and other information

Adds a new extractor for Callin. Works for both Python2 and Python3.
Supersedes, closes #31230.

Special thanks to @dirkf for the insights provided in the issue thread.