[extractor/youtube] Construct fragment list lazily

Ref: yt-dlp/yt-dlp/commit/e389d17
See: yt-dlp/yt-dlp#6517

1 files changed, 12 insertions, 6 deletions

diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index 89711c84e..6b153193c 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -31,6 +31,7 @@ from ..utils import (
     get_element_by_attribute,
     int_or_none,
     js_to_json,
+    LazyList,
     merge_dicts,
     mimetype2ext,
     parse_codecs,
@@ -1986,9 +1987,19 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         itags = []
         itag_qualities = {}
         q = qualities(['tiny', 'small', 'medium', 'large', 'hd720', 'hd1080', 'hd1440', 'hd2160', 'hd2880', 'highres'])
+        CHUNK_SIZE = 10 << 20
+
         streaming_data = player_response.get('streamingData') or {}
         streaming_formats = streaming_data.get('formats') or []
         streaming_formats.extend(streaming_data.get('adaptiveFormats') or [])
+
+        def build_fragments(f):
+            return LazyList({
+                'url': update_url_query(f['url'], {
+                    'range': '{0}-{1}'.format(range_start, min(range_start + CHUNK_SIZE - 1, f['filesize']))
+                })
+            } for range_start in range(0, f['filesize'], CHUNK_SIZE))
+
         for fmt in streaming_formats:
             if fmt.get('targetDurationSec') or fmt.get('drmFamilies'):
                 continue
@@ -2048,15 +2059,10 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
             if no_video:
                 dct['abr'] = tbr
             if no_audio or no_video:
-                CHUNK_SIZE = 10 << 20
                 # avoid Youtube throttling
                 dct.update({
                     'protocol': 'http_dash_segments',
-                    'fragments': [{
-                        'url': update_url_query(dct['url'], {
-                            'range': '{0}-{1}'.format(range_start, min(range_start + CHUNK_SIZE - 1, dct['filesize']))
-                        })
-                    } for range_start in range(0, dct['filesize'], CHUNK_SIZE)]
+                    'fragments': build_fragments(dct),
                 } if dct['filesize'] else {
                     'downloader_options': {'http_chunk_size': CHUNK_SIZE}  # No longer useful?
                 })