# Behavior traces — yt-dlp/yt-dlp

> Canonical page: https://codevetter.com/unpack/yt-dlp/behavior-traces

# Behavior traces — yt-dlp/yt-dlp

Scanned commit c7fb478d21e9e59524befbe23f7801bb267fb880 (2026-09-16). Generated by codevetter codevetter 1.12.0 on 2026-09-22.

Three end-to-end flows were traced in code. Startup: `__main__` -> `main` -> `_real_main` (options, plugins, updater, YoutubeDL init). Primary action: `download` -> `extract_info` -> IE regex match -> `ie.extract` -> `process_ie_result` -> `process_video_result` -> `process_info` -> `dl` -> FileDownloader -> post_process -> archive write. Persistence/self-update: `Updater.query_update` fetches `_update_spec` + `SHA2-256SUMS`, verifies sha256, atomically swaps the executable, and `restart()` re-invokes the original argv.
- Startup trace: `__main__.py` -> `yt_dlp.main()` sets `IN_CLI` -> `_real_main` calls `setproctitle('yt-dlp')` -> `parse_options` (optparse + config files) -> `print_extractor_information` handles `--list-*` -> `plugin_dirs`/`_load_all_plugins` -> `YoutubeDL(ydl_opts)` -> `Updater` if `-U` -> `ydl.download` or `download_with_info_file`. — [yt_dlp/__main__.py#L14-17](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/__main__.py#L14-L17) [yt_dlp/__init__.py#L964-1074](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/__init__.py#L964-L1074)
- YoutubeDL construction order: `__init__` stores params, initializes `_ies`/`_pps`, loads plugins if not loaded (`all_plugins_loaded`), resolves color policy and `_out_files`, applies js_runtimes/remote_components/compat_opts/http_headers, then `print_debug_header` when auto_init. — [yt_dlp/YoutubeDL.py#L634-751](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L634-L751)
- Per-URL trace: `download(url_list)` wraps `extract_info` in `__download_wrapper` (per-URL error containment, dump_single_json) -> `extract_info` scans `self._ies` for `ie.suitable(url)` -> `__extract_info` applies header cookies, calls `ie.extract(url)`, adds default extra info, calls `process_ie_result`. — [yt_dlp/YoutubeDL.py#L3681-3715](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3681-L3715) [yt_dlp/YoutubeDL.py#L1675-1719](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1675-L1719) [yt_dlp/YoutubeDL.py#L1861-1888](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1861-L1888)
- Inside `ie.extract`: `initialize()` -> `_initialize_pre_login` -> optional `_perform_login(username, password)` from `_get_login_info` -> `_real_initialize` -> `_real_extract(url)`; GeoRestrictedError triggers `__maybe_fake_ip_and_retry` once. — [yt_dlp/extractor/common.py#L653-671](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/extractor/common.py#L653-L671) [yt_dlp/extractor/common.py#L756-803](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/extractor/common.py#L756-L803)
- Video persistence trace: `process_ie_result` (video) -> `process_video_result` -> `process_info` -> `pre_process` PPs -> `prepare_filename`/`_ensure_dir_exists` -> `_write_description`/`_write_subtitles`/`_write_thumbnails` -> `dl()` -> `fd.download` -> `real_download` -> `post_process` PPs -> `record_download_archive`. — [yt_dlp/YoutubeDL.py#L1908](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1908) [yt_dlp/YoutubeDL.py#L2835](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2835) [yt_dlp/YoutubeDL.py#L3334-3395](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3334-L3395) [yt_dlp/downloader/common.py#L430-486](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/downloader/common.py#L430-L486)
- Playlist trace: `process_ie_result` sees `_type` playlist -> `__process_playlist` builds `PlaylistEntries` (lazy iteration) -> `__process_iterable_entry` per entry -> recursive `extract_info` on each entry URL with `extra_info` carrying playlist metadata. — [yt_dlp/YoutubeDL.py#L2080](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2080) [yt_dlp/YoutubeDL.py#L2199-2201](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2199-L2201)
- HTTP request trace: extractor calls `_request_webpage`/`_download_webpage` -> `_create_request` builds a `Request` -> `YoutubeDL.urlopen` sanitizes URL, injects basic auth, cleans proxies/headers -> `RequestDirector.send` -> handlers sorted by preference -> `handler.validate`/`handler.send` -> `Response` returned to extractor for parsing. — [yt_dlp/extractor/common.py#L864-924](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/extractor/common.py#L864-L924) [yt_dlp/YoutubeDL.py#L4281-4302](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L4281-L4302) [yt_dlp/networking/common.py#L94-120](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/networking/common.py#L94-L120)
- Self-update trace: `Updater.update` -> `query_update` -> `_download_update_spec`/`_process_update_spec` resolve tag -> `_download_asset('SHA2-256SUMS')` yields checksum -> `_download_asset(binary)` -> sha256 compare -> write `.new`, rename current to `.old`, rename `.new` -> `restart()` re-execs `self.cmd` via `Popen.run`. — [yt_dlp/update.py#L368-500](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/update.py#L368-L500) [yt_dlp/update.py#L502-610](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/update.py#L502-L610)
- Cookie-load trace: `--cookies-from-browser`/`--cookies` -> `YoutubeDL` cookiejar property -> `load_cookies` -> `_parse_browser_specification` -> `extract_cookies_from_browser` decrypts the browser store (AES via `aes.py`, keyrings via secretstorage) -> jar shared with every RequestHandler; saved back on `__exit__` via `save_cookies`. — [yt_dlp/cookies.py#L93-100](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/cookies.py#L93-L100) [yt_dlp/cookies.py#L23-32](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/cookies.py#L23-L32) [yt_dlp/YoutubeDL.py#L1053-1062](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1053-L1062)
- Plugin-load trace: each subsystem calls `register_plugin_spec(PluginSpec(module_name, suffix, ...))` which inserts a `PluginFinder` on `sys.meta_path`; `_real_main` calls `_load_all_plugins` -> `load_plugins` iterates `yt_dlp_plugins.<module>` submodules -> classes ending in the suffix are merged (plugins first) into the subsystem's Indirect dict. — [yt_dlp/plugins.py#L116-159](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/plugins.py#L116-L159) [yt_dlp/plugins.py#L194-247](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/plugins.py#L194-L247) [yt_dlp/extractor/__init__.py#L9-14](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/extractor/__init__.py#L9-L14) [yt_dlp/__init__.py#L977-980](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/__init__.py#L977-L980)
- Live-wait trace: for upcoming streams `_wait_for_video` computes a wait from `release_timestamp` (or randomized range), sleeps in a countdown loop, then raises `ReExtractInfo`, which `_handle_extraction_exceptions` catches to re-run the whole extraction. — [yt_dlp/YoutubeDL.py#L1725-1794](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1725-L1794)

Every claim links to its cited files at the pinned commit. Citations identify source evidence; they do not establish runtime correctness. Independent CodeVetter scan — not reviewed by upstream maintainers.

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