# Data flow — yt-dlp/yt-dlp

> Canonical page: https://codevetter.com/unpack/yt-dlp/data-flow

# Data flow — yt-dlp/yt-dlp

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

Data flows: CLI args + config files -> `ydl_opts` params dict -> URL list -> extractor selection by `_VALID_URL` regex -> `ie.extract()` performs HTTP via the shared RequestDirector and returns an info dict -> `process_ie_result` normalizes and recursively resolves playlists/URL results -> format selection computes `requested_formats` -> `process_info` writes sidecars and calls `dl()` -> a protocol FileDownloader streams bytes to `.part`/final files -> post-processors mutate files -> archive/cache/sidecar JSON are the persistence outputs. The info dict is the single mutable data structure threaded through the whole pipeline.
- Input boundary: `get_urls` merges argv URLs with batch-file/stdin lines; `parse_options` then produces the flat `ydl_opts` params dict consumed by `YoutubeDL`. — [yt_dlp/__init__.py#L83-100](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/__init__.py#L83-L100) [yt_dlp/__init__.py#L742-961](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/__init__.py#L742-L961)
- Extractor dispatch: `YoutubeDL.extract_info` iterates `self._ies` and picks the first extractor whose `suitable(url)` — a `_match_valid_url` regex match on `_VALID_URL` — returns true; no match yields 'No suitable extractor'. — [yt_dlp/YoutubeDL.py#L1699-1723](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1699-L1723) [yt_dlp/extractor/common.py#L615-631](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/extractor/common.py#L615-L631)
- `InfoExtractor.extract` runs `initialize()` (pre-login, `_perform_login`, geo-bypass setup, `_real_initialize`) then `_real_extract(url)`, and can retry once with a fake IP on GeoRestrictedError; errors are normalized into `ExtractorError`. — [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#L756-788](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/extractor/common.py#L756-L788)
- All extractor HTTP flows through `self._downloader.urlopen` -> `_request_director.send`, which applies basic-auth extraction, `sanitize_url`, proxy/header cleanup, then per-handler `validate`/`send` in preference order. — [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#L4281-4343](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L4281-L4343) [yt_dlp/networking/common.py#L94-140](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/networking/common.py#L94-L140)
- After extraction, `add_default_extra_info` stamps `webpage_url`, `original_url`, `extractor`, `extractor_key` onto the info dict; `process_ie_result` then dispatches on `_type` (video/playlist/url/compat_list) and `__process_playlist`/`__process_iterable_entry` recurse into entries via `extract_info`. — [yt_dlp/YoutubeDL.py#L1890-1908](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1890-L1908) [yt_dlp/YoutubeDL.py#L2080](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2080) [yt_dlp/YoutubeDL.py#L2199](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2199)
- Format selection: `build_format_selector` parses the `-f` spec into selector functions applied in `process_video_result`, producing `requested_formats` (split A/V) or a single format on the info dict. — [yt_dlp/YoutubeDL.py#L2341](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2341) [yt_dlp/YoutubeDL.py#L2835](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L2835)
- `process_info` computes filenames via `prepare_filename`, writes description/subtitles/thumbnails sidecars, then calls `self.dl(temp_filename, info_dict)`; multi-format downloads iterate `requested_formats` into separate files later merged. — [yt_dlp/YoutubeDL.py#L3334-3395](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3334-L3395) [yt_dlp/YoutubeDL.py#L3519-3586](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3519-L3586)
- `dl()` picks a FileDownloader via `get_suitable_downloader`, attaches progress hooks, and calls `fd.download(name, new_info)`; `FileDownloader.download` handles skip-if-present, sleep intervals, then `real_download` writes to `filename + '.part'` with resume metadata in `filename + '.ytdl'`. — [yt_dlp/YoutubeDL.py#L3286-3321](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3286-L3321) [yt_dlp/downloader/common.py#L217-230](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/downloader/common.py#L217-L230) [yt_dlp/downloader/common.py#L430-486](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/downloader/common.py#L430-L486)
- Post-processing is staged: `run_all_pps` iterates `self._pps[key]` for each `POSTPROCESS_WHEN` stage ('pre_process','after_filter','video','before_dl','post_process','after_move','after_video','playlist'), each `pp.run(infodict)` returning files to delete/move. — [yt_dlp/YoutubeDL.py#L3805-3853](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3805-L3853) [yt_dlp/utils/_utils.py#L2863](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/utils/_utils.py#L2863)
- Output boundaries: media files plus optional sidecars (`.info.json` via `_write_info_json`, `.description`, subtitle files, thumbnails), the download archive line append, and stdout JSON from `sanitize_info` (strips `__private` keys and non-serializable objects to repr). — [yt_dlp/YoutubeDL.py#L3740-3774](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3740-L3774) [yt_dlp/YoutubeDL.py#L4400-4423](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L4400-L4423) [yt_dlp/YoutubeDL.py#L3883-3894](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L3883-L3894)
- Cookies enter via `load_cookies` (browser extraction or Netscape file) into a `YoutubeDLCookieJar`, are attached to every request handler in `build_request_director`, and persisted on `YoutubeDL.__exit__`/`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/YoutubeDL.py#L4345-4378](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L4345-L4378) [yt_dlp/YoutubeDL.py#L1053-1062](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1053-L1062)
- Error flow: `_handle_extraction_exceptions` wraps extraction — `ReExtractInfo` loops, `GeoRestrictedError` reports with VPN hint, `ExtractorError` reports with optional traceback, `ignoreerrors` downgrades to report-only; the CLI exit code is `ydl._download_retcode` (e.g. 101 for DownloadCancelled). — [yt_dlp/YoutubeDL.py#L1725-1755](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/YoutubeDL.py#L1725-L1755) [yt_dlp/__init__.py#L1064-1093](https://github.com/yt-dlp/yt-dlp/blob/c7fb478d21e9e59524befbe23f7801bb267fb880/yt_dlp/__init__.py#L1064-L1093)

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