[downloader/hls] Fix incorrect end byte in Range HTTP header for medi…

…a segments with EXT-X-BYTERANGE (#24512) (closes #14748)

The end of the byte range is the first byte that is NOT part of the to
be downloaded range. So don't include it into the requested HTTP
download range, as this additional byte leads to a broken TS packet and
subsequently to e.g. visible video corruption.

Fixes #14748.

youtube_dl/downloader/hls.py

@@ -141,7 +141,7 @@ def is_ad_fragment_end(s):
                     count = 0
                     headers = info_dict.get('http_headers', {})
                     if byte_range:
-                        headers['Range'] = 'bytes=%d-%d' % (byte_range['start'], byte_range['end'])
+                        headers['Range'] = 'bytes=%d-%d' % (byte_range['start'], byte_range['end'] - 1)
                     while count <= fragment_retries:
                         try:
                             success, frag_content = self._download_fragment(