youtube-dl - download videos from youtube.com or other video platforms
- INSTALLATION
- DESCRIPTION
- OPTIONS
- CONFIGURATION
- OUTPUT TEMPLATE
- FORMAT SELECTION
- VIDEO SELECTION
- FAQ
- DEVELOPER INSTRUCTIONS
- EMBEDDING YOUTUBE-DL
- BUGS
- COPYRIGHT
To install it right away for all UNIX users (Linux, macOS, etc.), type:
sudo curl -L https://yt-dl.org/downloads/latest/youtube-dl -o /usr/local/bin/youtube-dl
sudo chmod a+rx /usr/local/bin/youtube-dl
If you do not have curl, you can alternatively use a recent wget:
sudo wget https://yt-dl.org/downloads/latest/youtube-dl -O /usr/local/bin/youtube-dl
sudo chmod a+rx /usr/local/bin/youtube-dl
Windows users can download an .exe file and place it in any location on their PATH except for %SYSTEMROOT%\System32
(e.g. do not put in C:\Windows\System32
).
You can also use pip:
sudo -H pip install --upgrade youtube-dl
This command will update youtube-dl if you have already installed it. See the pypi page for more information.
macOS users can install youtube-dl with Homebrew:
brew install youtube-dl
Or with MacPorts:
sudo port install youtube-dl
Alternatively, refer to the developer instructions for how to check out and work with the git repository. For further options, including PGP signatures, see the youtube-dl Download Page.
youtube-dl is a command-line program to download videos from YouTube.com and a few more sites. It requires the Python interpreter, version 2.6, 2.7, or 3.2+, and it is not platform specific. It should work on your Unix box, on Windows or on macOS. It is released to the public domain, which means you can modify it, redistribute it or use it however you like.
youtube-dl [OPTIONS] URL [URL...]
-h, --help Print this help text and exit
--version Print program version and exit
-U, --update Update this program to latest version. Make sure that you have sufficient permissions (run with sudo if needed)
-i, --ignore-errors Continue on download errors, for example to skip unavailable videos in a playlist
--abort-on-error Abort downloading of further videos (in the playlist or the command line) if an error occurs
--dump-user-agent Display the current browser identification
--list-extractors List all supported extractors
--extractor-descriptions Output descriptions of all supported extractors
--force-generic-extractor Force extraction to use the generic extractor
--default-search PREFIX Use this prefix for unqualified URLs. For example "gvsearch2:" downloads two videos from google videos for youtube-dl "large apple". Use the value "auto" to let youtube-dl guess ("auto_warning" to emit a warning when guessing). "error" just throws an error. The default value "fixup_error" repairs broken URLs, but emits an error if this is not possible instead of searching.
--ignore-config Do not read configuration files. When given in the global configuration file /etc/youtube-dl.conf: Do not read the user configuration in ~/.config/youtube- dl/config (%APPDATA%/youtube-dl/config.txt on Windows)
--config-location PATH Location of the configuration file; either the path to the config or its containing directory.
--flat-playlist Do not extract the videos of a playlist, only list them.
--mark-watched Mark videos watched (YouTube only)
--no-mark-watched Do not mark videos watched (YouTube only)
--no-color Do not emit color codes in output
--proxy URL Use the specified HTTP/HTTPS/SOCKS proxy. To enable SOCKS proxy, specify a proper scheme. For example socks5://127.0.0.1:1080/. Pass in an empty string (--proxy "") for direct connection
--socket-timeout SECONDS Time to wait before giving up, in seconds
--source-address IP Client-side IP address to bind to
-4, --force-ipv4 Make all connections via IPv4
-6, --force-ipv6 Make all connections via IPv6
--geo-verification-proxy URL Use this proxy to verify the IP address for some geo-restricted sites. The default proxy specified by --proxy (or none, if the option is not present) is used for the actual downloading.
--geo-bypass Bypass geographic restriction via faking X-Forwarded-For HTTP header
--no-geo-bypass Do not bypass geographic restriction via faking X-Forwarded-For HTTP header
--geo-bypass-country CODE Force bypass geographic restriction with explicitly provided two-letter ISO 3166-2 country code
--geo-bypass-ip-block IP_BLOCK Force bypass geographic restriction with explicitly provided IP block in CIDR notation
--playlist-start NUMBER Playlist video to start at (default is 1)
--playlist-end NUMBER Playlist video to end at (default is last)
--playlist-items ITEM_SPEC Playlist video items to download. Specify indices of the videos in the playlist separated by commas like: "--playlist-items 1,2,5,8" if you want to download videos indexed 1, 2, 5, 8 in the playlist. You can specify range: "--playlist-items 1-3,7,10-13", it will download the videos at index 1, 2, 3, 7, 10, 11, 12 and 13.
--match-title REGEX Download only matching titles (regex or caseless sub-string)
--reject-title REGEX Skip download for matching titles (regex or caseless sub-string)
--max-downloads NUMBER Abort after downloading NUMBER files
--min-filesize SIZE Do not download any videos smaller than SIZE (e.g. 50k or 44.6m)
--max-filesize SIZE Do not download any videos larger than SIZE (e.g. 50k or 44.6m)
--date DATE Download only videos uploaded in this date
--datebefore DATE Download only videos uploaded on or before this date (i.e. inclusive)
--dateafter DATE Download only videos uploaded on or after this date (i.e. inclusive)
--min-views COUNT Do not download any videos with less than COUNT views
--max-views COUNT Do not download any videos with more than COUNT views
--match-filter FILTER Generic video filter. Specify any key (see the "OUTPUT TEMPLATE" for a list of available keys) to match if the key is present, !key to check if the key is not present, key > NUMBER (like "comment_count > 12", also works with >=, <, <=, !=, =) to compare against a number, key = 'LITERAL' (like "uploader = 'Mike Smith'", also works with !=) to match against a string literal and & to require multiple matches. Values which are not known are excluded unless you put a question mark (?) after the operator. For example, to only match videos that have been liked more than 100 times and disliked less than 50 times (or the dislike functionality is not available at the given service), but who also have a description, use --match-filter "like_count > 100 & dislike_count <? 50 & description" .
--no-playlist Download only the video, if the URL refers to a video and a playlist.
--yes-playlist Download the playlist, if the URL refers to a video and a playlist.
--age-limit YEARS Download only videos suitable for the given age
--download-archive FILE Download only videos not listed in the archive file. Record the IDs of all downloaded videos in it.
--include-ads Download advertisements as well (experimental)
-r, --limit-rate RATE Maximum download rate in bytes per second (e.g. 50K or 4.2M)
-R, --retries RETRIES Number of retries (default is 10), or "infinite".
--fragment-retries RETRIES Number of retries for a fragment (default is 10), or "infinite" (DASH, hlsnative and ISM)
--skip-unavailable-fragments Skip unavailable fragments (DASH, hlsnative and ISM)
--abort-on-unavailable-fragment Abort downloading when some fragment is not available
--keep-fragments Keep downloaded fragments on disk after downloading is finished; fragments are erased by default
--buffer-size SIZE Size of download buffer (e.g. 1024 or 16K) (default is 1024)
--no-resize-buffer Do not automatically adjust the buffer size. By default, the buffer size is automatically resized from an initial value of SIZE.
--http-chunk-size SIZE Size of a chunk for chunk-based HTTP downloading (e.g. 10485760 or 10M) (default is disabled). May be useful for bypassing bandwidth throttling imposed by a webserver (experimental)
--playlist-reverse Download playlist videos in reverse order
--playlist-random Download playlist videos in random order
--xattr-set-filesize Set file xattribute ytdl.filesize with expected file size
--hls-prefer-native Use the native HLS downloader instead of ffmpeg
--hls-prefer-ffmpeg Use ffmpeg instead of the native HLS downloader
--hls-use-mpegts Use the mpegts container for HLS videos, allowing to play the video while downloading (some players may not be able to play it)
--external-downloader COMMAND Use the specified external downloader. Currently supports aria2c,avconv,axel,curl,ffmpeg,httpie,wget
--external-downloader-args ARGS Give these arguments to the external downloader
-a, --batch-file FILE File containing URLs to download ('-' for stdin), one URL per line. Lines starting with '#', ';' or ']' are considered as comments and ignored.
--id Use only video ID in file name
-o, --output TEMPLATE Output filename template, see the "OUTPUT TEMPLATE" for all the info
--autonumber-start NUMBER Specify the start value for %(autonumber)s (default is 1)
--restrict-filenames Restrict filenames to only ASCII characters, and avoid "&" and spaces in filenames
-w, --no-overwrites Do not overwrite files
-c, --continue Force resume of partially downloaded files. By default, youtube-dl will resume downloads if possible.
--no-continue Do not resume partially downloaded files (restart from beginning)
--no-part Do not use .part files - write directly into output file
--no-mtime Do not use the Last-modified header to set the file modification time
--write-description Write video description to a .description file
--write-info-json Write video metadata to a .info.json file
--write-annotations Write video annotations to a .annotations.xml file
--load-info-json FILE JSON file containing the video information (created with the "--write-info-json" option)
--cookies FILE File to read cookies from and dump cookie jar in
--cache-dir DIR Location in the filesystem where youtube-dl can store some downloaded information permanently. By default $XDG_CACHE_HOME/youtube-dl or ~/.cache/youtube-dl . At the moment, only YouTube player files (for videos with obfuscated signatures) are cached, but that may change.
--no-cache-dir Disable filesystem caching
--rm-cache-dir Delete all filesystem cache files
--write-thumbnail Write thumbnail image to disk
--write-all-thumbnails Write all thumbnail image formats to disk
--list-thumbnails Simulate and list all available thumbnail formats
-q, --quiet Activate quiet mode
--no-warnings Ignore warnings
-s, --simulate Do not download the video and do not write anything to disk
--skip-download Do not download the video
-g, --get-url Simulate, quiet but print URL
-e, --get-title Simulate, quiet but print title
--get-id Simulate, quiet but print id
--get-thumbnail Simulate, quiet but print thumbnail URL
--get-description Simulate, quiet but print video description
--get-duration Simulate, quiet but print video length
--get-filename Simulate, quiet but print output filename
--get-format Simulate, quiet but print output format
-j, --dump-json Simulate, quiet but print JSON information. See the "OUTPUT TEMPLATE" for a description of available keys.
-J, --dump-single-json Simulate, quiet but print JSON information for each command-line argument. If the URL refers to a playlist, dump the whole playlist information in a single line.
--print-json Be quiet and print the video information as JSON (video is still being downloaded).
--newline Output progress bar as new lines
--no-progress Do not print progress bar
--console-title Display progress in console titlebar
-v, --verbose Print various debugging information
--dump-pages Print downloaded pages encoded using base64 to debug problems (very verbose)
--write-pages Write downloaded intermediary pages to files in the current directory to debug problems
--print-traffic Display sent and read HTTP traffic
-C, --call-home Contact the youtube-dl server for debugging
--no-call-home Do NOT contact the youtube-dl server for debugging
--encoding ENCODING Force the specified encoding (experimental)
--no-check-certificate Suppress HTTPS certificate validation
--prefer-insecure Use an unencrypted connection to retrieve information about the video. (Currently supported only for YouTube)
--user-agent UA Specify a custom user agent
--referer URL Specify a custom referer, use if the video access is restricted to one domain
--add-header FIELD:VALUE Specify a custom HTTP header and its value, separated by a colon ':'. You can use this option multiple times
--bidi-workaround Work around terminals that lack bidirectional text support. Requires bidiv or fribidi executable in PATH
--sleep-interval SECONDS Number of seconds to sleep before each download when used alone or a lower bound of a range for randomized sleep before each download (minimum possible number of seconds to sleep) when used along with --max-sleep-interval.
--max-sleep-interval SECONDS Upper bound of a range for randomized sleep before each download (maximum possible number of seconds to sleep). Must only be used along with --min-sleep-interval.
-f, --format FORMAT Video format code, see the "FORMAT SELECTION" for all the info
--all-formats Download all available video formats
--prefer-free-formats Prefer free video formats unless a specific one is requested
-F, --list-formats List all available formats of requested videos
--youtube-skip-dash-manifest Do not download the DASH manifests and related data on YouTube videos
--merge-output-format FORMAT If a merge is required (e.g. bestvideo+bestaudio), output to given container format. One of mkv, mp4, ogg, webm, flv. Ignored if no merge is required
--write-sub Write subtitle file
--write-auto-sub Write automatically generated subtitle file (YouTube only)
--all-subs Download all the available subtitles of the video
--list-subs List all available subtitles for the video
--sub-format FORMAT Subtitle format, accepts formats preference, for example: "srt" or "ass/srt/best"
--sub-lang LANGS Languages of the subtitles to download (optional) separated by commas, use --list- subs for available language tags
-u, --username USERNAME Login with this account ID
-p, --password PASSWORD Account password. If this option is left out, youtube-dl will ask interactively.
-2, --twofactor TWOFACTOR Two-factor authentication code
-n, --netrc Use .netrc authentication data
--video-password PASSWORD Video password (vimeo, smotri, youku)
--ap-mso MSO Adobe Pass multiple-system operator (TV provider) identifier, use --ap-list-mso for a list of available MSOs
--ap-username USERNAME Multiple-system operator account login
--ap-password PASSWORD Multiple-system operator account password. If this option is left out, youtube-dl will ask interactively.
--ap-list-mso List all supported multiple-system operators
-x, --extract-audio Convert video files to audio-only files (requires ffmpeg or avconv and ffprobe or avprobe)
--audio-format FORMAT Specify audio format: "best", "aac", "flac", "mp3", "m4a", "opus", "vorbis", or "wav"; "best" by default; No effect without -x
--audio-quality QUALITY Specify ffmpeg/avconv audio quality, insert a value between 0 (better) and 9 (worse) for VBR or a specific bitrate like 128K (default 5)
--recode-video FORMAT Encode the video to another format if necessary (currently supported: mp4|flv|ogg|webm|mkv|avi)
--postprocessor-args ARGS Give these arguments to the postprocessor
-k, --keep-video Keep the video file on disk after the post- processing; the video is erased by default
--no-post-overwrites Do not overwrite post-processed files; the post-processed files are overwritten by default
--embed-subs Embed subtitles in the video (only for mp4, webm and mkv videos)
--embed-thumbnail Embed thumbnail in the audio as cover art
--add-metadata Write metadata to the video file
--metadata-from-title FORMAT Parse additional metadata like song title / artist from the video title. The format syntax is the same as --output. Regular expression with named capture groups may also be used. The parsed parameters replace existing values. Example: --metadata-from- title "%(artist)s - %(title)s" matches a title like "Coldplay - Paradise". Example (regex): --metadata-from-title "(?P<artist>.+?) - (?P<title>.+)"
--xattrs Write metadata to the video file's xattrs (using dublin core and xdg standards)
--fixup POLICY Automatically correct known faults of the file. One of never (do nothing), warn (only emit a warning), detect_or_warn (the default; fix file if we can, warn otherwise)
--prefer-avconv Prefer avconv over ffmpeg for running the postprocessors
--prefer-ffmpeg Prefer ffmpeg over avconv for running the postprocessors (default)
--ffmpeg-location PATH Location of the ffmpeg/avconv binary; either the path to the binary or its containing directory.
--exec CMD Execute a command on the file after downloading and post-processing, similar to find's -exec syntax. Example: --exec 'adb push {} /sdcard/Music/ && rm {}'
--convert-subs FORMAT Convert the subtitles to other format (currently supported: srt|ass|vtt|lrc)
You can configure youtube-dl by placing any supported command line option to a configuration file. On Linux and macOS, the system wide configuration file is located at /etc/youtube-dl.conf
and the user wide configuration file at ~/.config/youtube-dl/config
. On Windows, the user wide configuration file locations are %APPDATA%\youtube-dl\config.txt
or C:\Users\<user name>\youtube-dl.conf
. Note that by default configuration file may not exist so you may need to create it yourself.
For example, with the following configuration file youtube-dl will always extract the audio, not copy the mtime, use a proxy and save all videos under Movies
directory in your home directory:
# Lines starting with # are comments
# Always extract audio
-x
# Do not copy the mtime
--no-mtime
# Use this proxy
--proxy 127.0.0.1:3128
# Save all videos under Movies directory in your home directory
-o ~/Movies/%(title)s.%(ext)s
Note that options in configuration file are just the same options aka switches used in regular command line calls thus there must be no whitespace after -
or --
, e.g. -o
or --proxy
but not - o
or -- proxy
.
You can use --ignore-config
if you want to disable the configuration file for a particular youtube-dl run.
You can also use --config-location
if you want to use custom configuration file for a particular youtube-dl run.
You may also want to configure automatic credentials storage for extractors that support authentication (by providing login and password with --username
and --password
) in order not to pass credentials as command line arguments on every youtube-dl execution and prevent tracking plain text passwords in the shell command history. You can achieve this using a .netrc
file on a per extractor basis. For that you will need to create a .netrc
file in your $HOME
and restrict permissions to read/write by only you:
touch $HOME/.netrc
chmod a-rwx,u+rw $HOME/.netrc
After that you can add credentials for an extractor in the following format, where extractor is the name of the extractor in lowercase:
machine <extractor> login <login> password <password>
For example:
machine youtube login [email protected] password my_youtube_password
machine twitch login my_twitch_account_name password my_twitch_password
To activate authentication with the .netrc
file you should pass --netrc
to youtube-dl or place it in the configuration file.
On Windows you may also need to setup the %HOME%
environment variable manually. For example:
set HOME=%USERPROFILE%
The -o
option allows users to indicate a template for the output file names.
tl;dr: navigate me to examples.
The basic usage is not to set any template arguments when downloading a single file, like in youtube-dl -o funny_video.flv "https://some/video"
. However, it may contain special sequences that will be replaced when downloading each video. The special sequences may be formatted according to python string formatting operations. For example, %(NAME)s
or %(NAME)05d
. To clarify, that is a percent symbol followed by a name in parentheses, followed by formatting operations. Allowed names along with sequence type are:
id
(string): Video identifiertitle
(string): Video titleurl
(string): Video URLext
(string): Video filename extensionalt_title
(string): A secondary title of the videodisplay_id
(string): An alternative identifier for the videouploader
(string): Full name of the video uploaderlicense
(string): License name the video is licensed undercreator
(string): The creator of the videorelease_date
(string): The date (YYYYMMDD) when the video was releasedtimestamp
(numeric): UNIX timestamp of the moment the video became availableupload_date
(string): Video upload date (YYYYMMDD)uploader_id
(string): Nickname or id of the video uploaderchannel
(string): Full name of the channel the video is uploaded onchannel_id
(string): Id of the channellocation
(string): Physical location where the video was filmedduration
(numeric): Length of the video in secondsview_count
(numeric): How many users have watched the video on the platformlike_count
(numeric): Number of positive ratings of the videodislike_count
(numeric): Number of negative ratings of the videorepost_count
(numeric): Number of reposts of the videoaverage_rating
(numeric): Average rating give by users, the scale used depends on the webpagecomment_count
(numeric): Number of comments on the videoage_limit
(numeric): Age restriction for the video (years)is_live
(boolean): Whether this video is a live stream or a fixed-length videostart_time
(numeric): Time in seconds where the reproduction should start, as specified in the URLend_time
(numeric): Time in seconds where the reproduction should end, as specified in the URLformat
(string): A human-readable description of the formatformat_id
(string): Format code specified by--format
format_note
(string): Additional info about the formatwidth
(numeric): Width of the videoheight
(numeric): Height of the videoresolution
(string): Textual description of width and heighttbr
(numeric): Average bitrate of audio and video in KBit/sabr
(numeric): Average audio bitrate in KBit/sacodec
(string): Name of the audio codec in useasr
(numeric): Audio sampling rate in Hertzvbr
(numeric): Average video bitrate in KBit/sfps
(numeric): Frame ratevcodec
(string): Name of the video codec in usecontainer
(string): Name of the container formatfilesize
(numeric): The number of bytes, if known in advancefilesize_approx
(numeric): An estimate for the number of bytesprotocol
(string): The protocol that will be used for the actual downloadextractor
(string): Name of the extractorextractor_key
(string): Key name of the extractorepoch
(numeric): Unix epoch when creating the fileautonumber
(numeric): Number that will be increased with each download, starting at--autonumber-start
playlist
(string): Name or id of the playlist that contains the videoplaylist_index
(numeric): Index of the video in the playlist padded with leading zeros according to the total length of the playlistplaylist_id
(string): Playlist identifierplaylist_title
(string): Playlist titleplaylist_uploader
(string): Full name of the playlist uploaderplaylist_uploader_id
(string): Nickname or id of the playlist uploader
Available for the video that belongs to some logical chapter or section:
chapter
(string): Name or title of the chapter the video belongs tochapter_number
(numeric): Number of the chapter the video belongs tochapter_id
(string): Id of the chapter the video belongs to
Available for the video that is an episode of some series or programme:
series
(string): Title of the series or programme the video episode belongs toseason
(string): Title of the season the video episode belongs toseason_number
(numeric): Number of the season the video episode belongs toseason_id
(string): Id of the season the video episode belongs toepisode
(string): Title of the video episodeepisode_number
(numeric): Number of the video episode within a seasonepisode_id
(string): Id of the video episode
Available for the media that is a track or a part of a music album:
track
(string): Title of the tracktrack_number
(numeric): Number of the track within an album or a disctrack_id
(string): Id of the trackartist
(string): Artist(s) of the trackgenre
(string): Genre(s) of the trackalbum
(string): Title of the album the track belongs toalbum_type
(string): Type of the albumalbum_artist
(string): List of all artists appeared on the albumdisc_number
(numeric): Number of the disc or other physical medium the track belongs torelease_year
(numeric): Year (YYYY) when the album was released
Each aforementioned sequence when referenced in an output template will be replaced by the actual value corresponding to the sequence name. Note that some of the sequences are not guaranteed to be present since they depend on the metadata obtained by a particular extractor. Such sequences will be replaced with NA
.
For example for -o %(title)s-%(id)s.%(ext)s
and an mp4 video with title youtube-dl test video
and id BaW_jenozKcj
, this will result in a youtube-dl test video-BaW_jenozKcj.mp4
file created in the current directory.
For numeric sequences you can use numeric related formatting, for example, %(view_count)05d
will result in a string with view count padded with zeros up to 5 characters, like in 00042
.
Output templates can also contain arbitrary hierarchical path, e.g. -o '%(playlist)s/%(playlist_index)s - %(title)s.%(ext)s'
which will result in downloading each video in a directory corresponding to this path template. Any missing directory will be automatically created for you.
To use percent literals in an output template use %%
. To output to stdout use -o -
.
The current default template is %(title)s-%(id)s.%(ext)s
.
In some cases, you don't want special characters such as ไธญ, spaces, or &, such as when transferring the downloaded filename to a Windows system or the filename through an 8bit-unsafe channel. In these cases, add the --restrict-filenames
flag to get a shorter title:
If you are using an output template inside a Windows batch file then you must escape plain percent characters (%
) by doubling, so that -o "%(title)s-%(id)s.%(ext)s"
should become -o "%%(title)s-%%(id)s.%%(ext)s"
. However you should not touch %
's that are not plain characters, e.g. environment variables for expansion should stay intact: -o "C:\%HOMEPATH%\Desktop\%%(title)s.%%(ext)s"
.
Note that on Windows you may need to use double quotes instead of single.
$ youtube-dl --get-filename -o '%(title)s.%(ext)s' BaW_jenozKc
youtube-dl test video ''_รคโญ๐.mp4 # All kinds of weird characters
$ youtube-dl --get-filename -o '%(title)s.%(ext)s' BaW_jenozKc --restrict-filenames
youtube-dl_test_video_.mp4 # A simple file name
# Download YouTube playlist videos in separate directory indexed by video order in a playlist
$ youtube-dl -o '%(playlist)s/%(playlist_index)s - %(title)s.%(ext)s' https://www.youtube.com/playlist?list=PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re
# Download all playlists of YouTube channel/user keeping each playlist in separate directory:
$ youtube-dl -o '%(uploader)s/%(playlist)s/%(playlist_index)s - %(title)s.%(ext)s' https://www.youtube.com/user/TheLinuxFoundation/playlists
# Download Udemy course keeping each chapter in separate directory under MyVideos directory in your home
$ youtube-dl -u user -p password -o '~/MyVideos/%(playlist)s/%(chapter_number)s - %(chapter)s/%(title)s.%(ext)s' https://www.udemy.com/java-tutorial/
# Download entire series season keeping each series and each season in separate directory under C:/MyVideos
$ youtube-dl -o "C:/MyVideos/%(series)s/%(season_number)s - %(season)s/%(episode_number)s - %(episode)s.%(ext)s" https://videomore.ru/kino_v_detalayah/5_sezon/367617
# Stream the video being downloaded to stdout
$ youtube-dl -o - BaW_jenozKc
By default youtube-dl tries to download the best available quality, i.e. if you want the best quality you don't need to pass any special options, youtube-dl will guess it for you by default.
But sometimes you may want to download in a different format, for example when you are on a slow or intermittent connection. The key mechanism for achieving this is so-called format selection based on which you can explicitly specify desired format, select formats based on some criterion or criteria, setup precedence and much more.
The general syntax for format selection is --format FORMAT
or shorter -f FORMAT
where FORMAT
is a selector expression, i.e. an expression that describes format or formats you would like to download.
tl;dr: navigate me to examples.
The simplest case is requesting a specific format, for example with -f 22
you can download the format with format code equal to 22. You can get the list of available format codes for particular video using --list-formats
or -F
. Note that these format codes are extractor specific.
You can also use a file extension (currently 3gp
, aac
, flv
, m4a
, mp3
, mp4
, ogg
, wav
, webm
are supported) to download the best quality format of a particular file extension served as a single file, e.g. -f webm
will download the best quality format with the webm
extension served as a single file.
You can also use special names to select particular edge case formats:
best
: Select the best quality format represented by a single file with video and audio.worst
: Select the worst quality format represented by a single file with video and audio.bestvideo
: Select the best quality video-only format (e.g. DASH video). May not be available.worstvideo
: Select the worst quality video-only format. May not be available.bestaudio
: Select the best quality audio only-format. May not be available.worstaudio
: Select the worst quality audio only-format. May not be available.
For example, to download the worst quality video-only format you can use -f worstvideo
.
If you want to download multiple videos and they don't have the same formats available, you can specify the order of preference using slashes. Note that slash is left-associative, i.e. formats on the left hand side are preferred, for example -f 22/17/18
will download format 22 if it's available, otherwise it will download format 17 if it's available, otherwise it will download format 18 if it's available, otherwise it will complain that no suitable formats are available for download.
If you want to download several formats of the same video use a comma as a separator, e.g. -f 22,17,18
will download all these three formats, of course if they are available. Or a more sophisticated example combined with the precedence feature: -f 136/137/mp4/bestvideo,140/m4a/bestaudio
.
You can also filter the video formats by putting a condition in brackets, as in -f "best[height=720]"
(or -f "[filesize>10M]"
).
The following numeric meta fields can be used with comparisons <
, <=
, >
, >=
, =
(equals), !=
(not equals):
filesize
: The number of bytes, if known in advancewidth
: Width of the video, if knownheight
: Height of the video, if knowntbr
: Average bitrate of audio and video in KBit/sabr
: Average audio bitrate in KBit/svbr
: Average video bitrate in KBit/sasr
: Audio sampling rate in Hertzfps
: Frame rate
Also filtering work for comparisons =
(equals), ^=
(starts with), $=
(ends with), *=
(contains) and following string meta fields:
ext
: File extensionacodec
: Name of the audio codec in usevcodec
: Name of the video codec in usecontainer
: Name of the container formatprotocol
: The protocol that will be used for the actual download, lower-case (http
,https
,rtsp
,rtmp
,rtmpe
,mms
,f4m
,ism
,http_dash_segments
,m3u8
, orm3u8_native
)format_id
: A short description of the format
Any string comparison may be prefixed with negation !
in order to produce an opposite comparison, e.g. !*=
(does not contain).
Note that none of the aforementioned meta fields are guaranteed to be present since this solely depends on the metadata obtained by particular extractor, i.e. the metadata offered by the video hoster.
Formats for which the value is not known are excluded unless you put a question mark (?
) after the operator. You can combine format filters, so -f "[height <=? 720][tbr>500]"
selects up to 720p videos (or videos where the height is not known) with a bitrate of at least 500 KBit/s.
You can merge the video and audio of two formats into a single file using -f <video-format>+<audio-format>
(requires ffmpeg or avconv installed), for example -f bestvideo+bestaudio
will download the best video-only format, the best audio-only format and mux them together with ffmpeg/avconv.
Format selectors can also be grouped using parentheses, for example if you want to download the best mp4 and webm formats with a height lower than 480 you can use -f '(mp4,webm)[height<480]'
.
Since the end of April 2015 and version 2015.04.26, youtube-dl uses -f bestvideo+bestaudio/best
as the default format selection (see #5447, #5456). If ffmpeg or avconv are installed this results in downloading bestvideo
and bestaudio
separately and muxing them together into a single file giving the best overall quality available. Otherwise it falls back to best
and results in downloading the best available quality served as a single file. best
is also needed for videos that don't come from YouTube because they don't provide the audio and video in two different files. If you want to only download some DASH formats (for example if you are not interested in getting videos with a resolution higher than 1080p), you can add -f bestvideo[height<=?1080]+bestaudio/best
to your configuration file. Note that if you use youtube-dl to stream to stdout
(and most likely to pipe it to your media player then), i.e. you explicitly specify output template as -o -
, youtube-dl still uses -f best
format selection in order to start content delivery immediately to your player and not to wait until bestvideo
and bestaudio
are downloaded and muxed.
If you want to preserve the old format selection behavior (prior to youtube-dl 2015.04.26), i.e. you want to download the best available quality media served as a single file, you should explicitly specify your choice with -f best
. You may want to add it to the configuration file in order not to type it every time you run youtube-dl.
Note that on Windows you may need to use double quotes instead of single.
# Download best mp4 format available or any other best if no mp4 available
$ youtube-dl -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best'
# Download best format available but no better than 480p
$ youtube-dl -f 'bestvideo[height<=480]+bestaudio/best[height<=480]'
# Download best video only format but no bigger than 50 MB
$ youtube-dl -f 'best[filesize<50M]'
# Download best format available via direct link over HTTP/HTTPS protocol
$ youtube-dl -f '(bestvideo+bestaudio/best)[protocol^=http]'
# Download the best video format and the best audio format without merging them
$ youtube-dl -f 'bestvideo,bestaudio' -o '%(title)s.f%(format_id)s.%(ext)s'
Note that in the last example, an output template is recommended as bestvideo and bestaudio may have the same file name.
Videos can be filtered by their upload date using the options --date
, --datebefore
or --dateafter
. They accept dates in two formats:
- Absolute dates: Dates in the format
YYYYMMDD
. - Relative dates: Dates in the format
(now|today)[+-][0-9](day|week|month|year)(s)?
Examples:
# Download only the videos uploaded in the last 6 months
$ youtube-dl --dateafter now-6months
# Download only the videos uploaded on January 1, 1970
$ youtube-dl --date 19700101
$ # Download only the videos uploaded in the 200x decade
$ youtube-dl --dateafter 20000101 --datebefore 20091231
If you've followed our manual installation instructions, you can simply run youtube-dl -U
(or, on Linux, sudo youtube-dl -U
).
If you have used pip, a simple sudo pip install -U youtube-dl
is sufficient to update.
If you have installed youtube-dl using a package manager like apt-get or yum, use the standard system update mechanism to update. Note that distribution packages are often outdated. As a rule of thumb, youtube-dl releases at least once a month, and often weekly or even daily. Simply go to https://yt-dl.org to find out the current version. Unfortunately, there is nothing we youtube-dl developers can do if your distribution serves a really outdated version. You can (and should) complain to your distribution in their bugtracker or support forum.
As a last resort, you can also uninstall the version installed by your package manager and follow our manual installation instructions. For that, remove the distribution's package, with a line like
sudo apt-get remove -y youtube-dl
Afterwards, simply follow our manual installation instructions:
sudo wget https://yt-dl.org/downloads/latest/youtube-dl -O /usr/local/bin/youtube-dl
sudo chmod a+rx /usr/local/bin/youtube-dl
hash -r
Again, from then on you'll be able to update with sudo youtube-dl -U
.
Add a file exclusion for youtube-dl.exe
in Windows Defender settings.
YouTube changed their playlist format in March 2014 and later on, so you'll need at least youtube-dl 2014.07.25 to download all YouTube videos.
If you have installed youtube-dl with a package manager, pip, setup.py or a tarball, please use that to update. Note that Ubuntu packages do not seem to get updated anymore. Since we are not affiliated with Ubuntu, there is little we can do. Feel free to report bugs to the Ubuntu packaging people - all they have to do is update the package to a somewhat recent version. See above for a way to update.
I'm getting an error when trying to use output template: error: using output template conflicts with using title, video ID or auto number
Make sure you are not using -o
with any of these options -t
, --title
, --id
, -A
or --auto-number
set in command line or in a configuration file. Remove the latter if any.
By default, youtube-dl intends to have the best options (incidentally, if you have a convincing case that these should be different, please file an issue where you explain that). Therefore, it is unnecessary and sometimes harmful to copy long option strings from webpages. In particular, the only option out of -citw
that is regularly useful is -i
.
Most people asking this question are not aware that youtube-dl now defaults to downloading the highest available quality as reported by YouTube, which will be 1080p or 720p in some cases, so you no longer need the -b
option. For some specific videos, maybe YouTube does not report them to be available in a specific high quality format you're interested in. In that case, simply request it with the -f
option and youtube-dl will try to download it.
Apparently YouTube requires you to pass a CAPTCHA test if you download too much. We're considering to provide a way to let you solve the CAPTCHA, but at the moment, your best course of action is pointing a web browser to the youtube URL, solving the CAPTCHA, and restart youtube-dl.
youtube-dl works fine on its own on most sites. However, if you want to convert video/audio, you'll need avconv or ffmpeg. On some sites - most notably YouTube - videos can be retrieved in a higher quality format without sound. youtube-dl will detect whether avconv/ffmpeg is present and automatically pick the best option.
Videos or video formats streamed via RTMP protocol can only be downloaded when rtmpdump is installed. Downloading MMS and RTSP videos requires either mplayer or mpv to be installed.
Once the video is fully downloaded, use any video player, such as mpv, vlc or mplayer.
It depends a lot on the service. In many cases, requests for the video (to download/play it) must come from the same IP address and with the same cookies and/or HTTP headers. Use the --cookies
option to write the required cookies into a file, and advise your downloader to read cookies from that file. Some sites also require a common user agent to be used, use --dump-user-agent
to see the one in use by youtube-dl. You can also get necessary cookies and HTTP headers from JSON output obtained with --dump-json
.
It may be beneficial to use IPv6; in some cases, the restrictions are only applied to IPv4. Some services (sometimes only for a subset of videos) do not restrict the video URL by IP address, cookie, or user-agent, but these are the exception rather than the rule.
Please bear in mind that some URL protocols are not supported by browsers out of the box, including RTMP. If you are using -g
, your own downloader must support these as well.
If you want to play the video on a machine that is not running youtube-dl, you can relay the video content from the machine that runs youtube-dl. You can use -o -
to let youtube-dl stream a video to stdout, or simply allow the player to download the files written by youtube-dl in turn.
YouTube has switched to a new video info format in July 2011 which is not supported by old versions of youtube-dl. See above for how to update youtube-dl.
YouTube requires an additional signature since September 2012 which is not supported by old versions of youtube-dl. See above for how to update youtube-dl.
Video URL contains an ampersand and I'm getting some strange output [1] 2839
or 'v' is not recognized as an internal or external command
That's actually the output from your shell. Since ampersand is one of the special shell characters it's interpreted by the shell preventing you from passing the whole URL to youtube-dl. To disable your shell from interpreting the ampersands (or any other special characters) you have to either put the whole URL in quotes or escape them with a backslash (which approach will work depends on your shell).
For example if your URL is https://www.youtube.com/watch?t=4&v=BaW_jenozKc you should end up with following command:
youtube-dl 'https://www.youtube.com/watch?t=4&v=BaW_jenozKc'
or
youtube-dl https://www.youtube.com/watch?t=4\&v=BaW_jenozKc
For Windows you have to use the double quotes:
youtube-dl "https://www.youtube.com/watch?t=4&v=BaW_jenozKc"
In February 2015, the new YouTube player contained a character sequence in a string that was misinterpreted by old versions of youtube-dl. See above for how to update youtube-dl.
These two error codes indicate that the service is blocking your IP address because of overuse. Usually this is a soft block meaning that you can gain access again after solving CAPTCHA. Just open a browser and solve a CAPTCHA the service suggests you and after that pass cookies to youtube-dl. Note that if your machine has multiple external IPs then you should also pass exactly the same IP you've used for solving CAPTCHA with --source-address
. Also you may need to pass a User-Agent
HTTP header of your browser with --user-agent
.
If this is not the case (no CAPTCHA suggested to solve by the service) then you can contact the service and ask them to unblock your IP address, or - if you have acquired a whitelisted IP address already - use the --proxy
or --source-address
options to select another IP address.
The error
File "youtube-dl", line 2
SyntaxError: Non-ASCII character '\x93' ...
means you're using an outdated version of Python. Please update to Python 2.6 or 2.7.
Since June 2012 (#342) youtube-dl is packed as an executable zipfile, simply unzip it (might need renaming to youtube-dl.zip
first on some systems) or clone the git repository, as laid out above. If you modify the code, you can run it by executing the __main__.py
file. To recompile the executable, run make youtube-dl
.
To run the exe you need to install first the Microsoft Visual C++ 2010 Redistributable Package (x86).
If you put youtube-dl and ffmpeg in the same directory that you're running the command from, it will work, but that's rather cumbersome.
To make a different directory work - either for ffmpeg, or for youtube-dl, or for both - simply create the directory (say, C:\bin
, or C:\Users\<User name>\bin
), put all the executables directly in there, and then set your PATH environment variable to include that directory.
From then on, after restarting your shell, you will be able to access both youtube-dl and ffmpeg (and youtube-dl will be able to find ffmpeg) by simply typing youtube-dl
or ffmpeg
, no matter what directory you're in.
Use the -o
to specify an output template, for example -o "/home/user/videos/%(title)s-%(id)s.%(ext)s"
. If you want this for all of your downloads, put the option into your configuration file.
Either prepend https://www.youtube.com/watch?v=
or separate the ID from the options with --
:
youtube-dl -- -wNyEUrxzFU
youtube-dl "https://www.youtube.com/watch?v=-wNyEUrxzFU"
Use the --cookies
option, for example --cookies /path/to/cookies/file.txt
.
In order to extract cookies from browser use any conforming browser extension for exporting cookies. For example, cookies.txt (for Chrome) or cookies.txt (for Firefox).
Note that the cookies file must be in Mozilla/Netscape format and the first line of the cookies file must be either # HTTP Cookie File
or # Netscape HTTP Cookie File
. Make sure you have correct newline format in the cookies file and convert newlines if necessary to correspond with your OS, namely CRLF
(\r\n
) for Windows and LF
(\n
) for Unix and Unix-like systems (Linux, macOS, etc.). HTTP Error 400: Bad Request
when using --cookies
is a good sign of invalid newline format.
Passing cookies to youtube-dl is a good way to workaround login when a particular extractor does not implement it explicitly. Another use case is working around CAPTCHA some websites require you to solve in particular cases in order to get access (e.g. YouTube, CloudFlare).
You will first need to tell youtube-dl to stream media to stdout with -o -
, and also tell your media player to read from stdin (it must be capable of this for streaming) and then pipe former to latter. For example, streaming to vlc can be achieved with:
youtube-dl -o - "https://www.youtube.com/watch?v=BaW_jenozKcj" | vlc -
Use download-archive feature. With this feature you should initially download the complete playlist with --download-archive /path/to/download/archive/file.txt
that will record identifiers of all the videos in a special file. Each subsequent run with the same --download-archive
will download only new videos and skip all videos that have been downloaded before. Note that only successful downloads are recorded in the file.
For example, at first,
youtube-dl --download-archive archive.txt "https://www.youtube.com/playlist?list=PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re"
will download the complete PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re
playlist and create a file archive.txt
. Each subsequent run will only download new videos if any:
youtube-dl --download-archive archive.txt "https://www.youtube.com/playlist?list=PLwiyx1dc3P2JR9N8gQaQN_BCvlSlap7re"
When youtube-dl detects an HLS video, it can download it either with the built-in downloader or ffmpeg. Since many HLS streams are slightly invalid and ffmpeg/youtube-dl each handle some invalid cases better than the other, there is an option to switch the downloader if needed.
When youtube-dl knows that one particular downloader works better for a given website, that downloader will be picked. Otherwise, youtube-dl will pick the best downloader for general compatibility, which at the moment happens to be ffmpeg. This choice may change in future versions of youtube-dl, with improvements of the built-in downloader and/or ffmpeg.
In particular, the generic extractor (used when your website is not in the list of supported sites by youtube-dl cannot mandate one specific downloader.
If you put either --hls-prefer-native
or --hls-prefer-ffmpeg
into your configuration, a different subset of videos will fail to download correctly. Instead, it is much better to file an issue or a pull request which details why the native or the ffmpeg HLS downloader is a better choice for your use case.
As a matter of policy (as well as legality), youtube-dl does not include support for services that specialize in infringing copyright. As a rule of thumb, if you cannot easily find a video that the service is quite obviously allowed to distribute (i.e. that has been uploaded by the creator, the creator's distributor, or is published under a free license), the service is probably unfit for inclusion to youtube-dl.
A note on the service that they don't host the infringing content, but just link to those who do, is evidence that the service should not be included into youtube-dl. The same goes for any DMCA note when the whole front page of the service is filled with videos they are not allowed to distribute. A "fair use" note is equally unconvincing if the service shows copyright-protected videos in full without authorization.
Support requests for services that do purchase the rights to distribute their content are perfectly fine though. If in doubt, you can simply include a source that mentions the legitimate purchase of content.
(Also known as: Help, my important issue not being solved!) The youtube-dl core developer team is quite small. While we do our best to solve as many issues as possible, sometimes that can take quite a while. To speed up your issue, here's what you can do:
First of all, please do report the issue at our issue tracker. That allows us to coordinate all efforts by users and developers, and serves as a unified point. Unfortunately, the youtube-dl project has grown too large to use personal email as an effective communication channel.
Please read the bug reporting instructions below. A lot of bugs lack all the necessary information. If you can, offer proxy, VPN, or shell access to the youtube-dl developers. If you are able to, test the issue from multiple computers in multiple countries to exclude local censorship or misconfiguration issues.
If nobody is interested in solving your issue, you are welcome to take matters into your own hands and submit a pull request (or coerce/pay somebody else to do so).
Feel free to bump the issue from time to time by writing a small comment ("Issue is still present in youtube-dl version ...from France, but fixed from Belgium"), but please not more than once a month. Please do not declare your issue as important
or urgent
.
For one, have a look at the list of supported sites. Note that it can sometimes happen that the site changes its URL scheme (say, from https://example.com/video/1234567 to https://example.com/v/1234567 ) and youtube-dl reports an URL of a service in that list as unsupported. In that case, simply report a bug.
It is not possible to detect whether a URL is supported or not. That's because youtube-dl contains a generic extractor which matches all URLs. You may be tempted to disable, exclude, or remove the generic extractor, but the generic extractor not only allows users to extract videos from lots of websites that embed a video from another service, but may also be used to extract video from a service that it's hosting itself. Therefore, we neither recommend nor support disabling, excluding, or removing the generic extractor.
If you want to find out whether a given URL is supported, simply call youtube-dl with it. If you get no videos back, chances are the URL is either not referring to a video or unsupported. You can find out which by examining the output (if you run youtube-dl on the console) or catching an UnsupportedError
exception if you run it from a Python program.
Before we had the issue template, despite our extensive bug reporting instructions, about 80% of the issue reports we got were useless, for instance because people used ancient versions hundreds of releases old, because of simple syntactic errors (not in youtube-dl but in general shell usage), because the problem was already reported multiple times before, because people did not actually read an error message, even if it said "please install ffmpeg", because people did not mention the URL they were trying to download and many more simple, easy-to-avoid problems, many of whom were totally unrelated to youtube-dl.
youtube-dl is an open-source project manned by too few volunteers, so we'd rather spend time fixing bugs where we are certain none of those simple problems apply, and where we can be reasonably confident to be able to reproduce the issue without asking the reporter repeatedly. As such, the output of youtube-dl -v YOUR_URL_HERE
is really all that's required to file an issue. The issue template also guides you through some basic steps you can do, such as checking that your version of youtube-dl is current.
Most users do not need to build youtube-dl and can download the builds or get them from their distribution.
To run youtube-dl as a developer, you don't need to build anything either. Simply execute
python -m youtube_dl
To run the test, simply invoke your favorite test runner, or execute a test file directly; any of the following work:
python -m unittest discover
python test/test_download.py
nosetests
See item 6 of new extractor tutorial for how to run extractor specific test cases.
If you want to create a build of youtube-dl yourself, you'll need
- python
- make (only GNU make is supported)
- pandoc
- zip
- nosetests
If you want to add support for a new site, first of all make sure this site is not dedicated to copyright infringement. youtube-dl does not support such sites thus pull requests adding support for them will be rejected.
After you have ensured this site is distributing its content legally, you can follow this quick list (assuming your service is called yourextractor
):
-
Check out the source code with:
git clone [email protected]:YOUR_GITHUB_USERNAME/youtube-dl.git
-
Start a new git branch with
cd youtube-dl git checkout -b yourextractor
-
Start with this simple template and save it to
youtube_dl/extractor/yourextractor.py
:# coding: utf-8 from __future__ import unicode_literals from .common import InfoExtractor class YourExtractorIE(InfoExtractor): _VALID_URL = r'https?://(?:www\.)?yourextractor\.com/watch/(?P<id>[0-9]+)' _TEST = { 'url': 'https://yourextractor.com/watch/42', 'md5': 'TODO: md5 sum of the first 10241 bytes of the video file (use --test)', 'info_dict': { 'id': '42', 'ext': 'mp4', 'title': 'Video title goes here', 'thumbnail': r're:^https?://.*\.jpg$', # TODO more properties, either as: # * A value # * MD5 checksum; start the string with md5: # * A regular expression; start the string with re: # * Any Python type (for example int or float) } } def _real_extract(self, url): video_id = self._match_id(url) webpage = self._download_webpage(url, video_id) # TODO more code goes here, for example ... title = self._html_search_regex(r'<h1>(.+?)</h1>', webpage, 'title') return { 'id': video_id, 'title': title, 'description': self._og_search_description(webpage), 'uploader': self._search_regex(r'<div[^>]+id="uploader"[^>]*>([^<]+)<', webpage, 'uploader', fatal=False), # TODO more properties (see youtube_dl/extractor/common.py) }
-
Add an import in
youtube_dl/extractor/extractors.py
. -
Run
python test/test_download.py TestDownload.test_YourExtractor
. This should fail at first, but you can continually re-run it until you're done. If you decide to add more than one test, then rename_TEST
to_TESTS
and make it into a list of dictionaries. The tests will then be namedTestDownload.test_YourExtractor
,TestDownload.test_YourExtractor_1
,TestDownload.test_YourExtractor_2
, etc. Note that tests withonly_matching
key in test's dict are not counted in. -
Have a look at
youtube_dl/extractor/common.py
for possible helper methods and a detailed description of what your extractor should and may return. Add tests and code for as many as you want. -
Make sure your code follows youtube-dl coding conventions and check the code with flake8:
$ flake8 youtube_dl/extractor/yourextractor.py
-
Make sure your code works under all Python versions claimed supported by youtube-dl, namely 2.6, 2.7, and 3.2+.
-
When the tests pass, add the new files and commit them and push the result, like this:
$ git add youtube_dl/extractor/extractors.py $ git add youtube_dl/extractor/yourextractor.py $ git commit -m '[yourextractor] Add new extractor' $ git push origin yourextractor
-
Finally, create a pull request. We'll then review and merge it.
In any case, thank you very much for your contributions!
This section introduces a guide lines for writing idiomatic, robust and future-proof extractor code.
Extractors are very fragile by nature since they depend on the layout of the source data provided by 3rd party media hosters out of your control and this layout tends to change. As an extractor implementer your task is not only to write code that will extract media links and metadata correctly but also to minimize dependency on the source's layout and even to make the code foresee potential future changes and be ready for that. This is important because it will allow the extractor not to break on minor layout changes thus keeping old youtube-dl versions working. Even though this breakage issue is easily fixed by emitting a new version of youtube-dl with a fix incorporated, all the previous versions become broken in all repositories and distros' packages that may not be so prompt in fetching the update from us. Needless to say, some non rolling release distros may never receive an update at all.
For extraction to work youtube-dl relies on metadata your extractor extracts and provides to youtube-dl expressed by an information dictionary or simply info dict. Only the following meta fields in the info dict are considered mandatory for a successful extraction process by youtube-dl:
id
(media identifier)title
(media title)url
(media download URL) orformats
In fact only the last option is technically mandatory (i.e. if you can't figure out the download location of the media the extraction does not make any sense). But by convention youtube-dl also treats id
and title
as mandatory. Thus the aforementioned metafields are the critical data that the extraction does not make any sense without and if any of them fail to be extracted then the extractor is considered completely broken.
Any field apart from the aforementioned ones are considered optional. That means that extraction should be tolerant to situations when sources for these fields can potentially be unavailable (even if they are always available at the moment) and future-proof in order not to break the extraction of general purpose mandatory fields.
Say you have some source dictionary meta
that you've fetched as JSON with HTTP request and it has a key summary
:
meta = self._download_json(url, video_id)
Assume at this point meta
's layout is:
{
...
"summary": "some fancy summary text",
...
}
Assume you want to extract summary
and put it into the resulting info dict as description
. Since description
is an optional meta field you should be ready that this key may be missing from the meta
dict, so that you should extract it like:
description = meta.get('summary') # correct
and not like:
description = meta['summary'] # incorrect
The latter will break extraction process with KeyError
if summary
disappears from meta
at some later time but with the former approach extraction will just go ahead with description
set to None
which is perfectly fine (remember None
is equivalent to the absence of data).
Similarly, you should pass fatal=False
when extracting optional data from a webpage with _search_regex
, _html_search_regex
or similar methods, for instance:
description = self._search_regex(
r'<span[^>]+id="title"[^>]*>([^<]+)<',
webpage, 'description', fatal=False)
With fatal
set to False
if _search_regex
fails to extract description
it will emit a warning and continue extraction.
You can also pass default=<some fallback value>
, for example:
description = self._search_regex(
r'<span[^>]+id="title"[^>]*>([^<]+)<',
webpage, 'description', default=None)
On failure this code will silently continue the extraction with description
set to None
. That is useful for metafields that may or may not be present.
When extracting metadata try to do so from multiple sources. For example if title
is present in several places, try extracting from at least some of them. This makes it more future-proof in case some of the sources become unavailable.
Say meta
from the previous example has a title
and you are about to extract it. Since title
is a mandatory meta field you should end up with something like:
title = meta['title']
If title
disappears from meta
in future due to some changes on the hoster's side the extraction would fail since title
is mandatory. That's expected.
Assume that you have some another source you can extract title
from, for example og:title
HTML meta of a webpage
. In this case you can provide a fallback scenario:
title = meta.get('title') or self._og_search_title(webpage)
This code will try to extract from meta
first and if it fails it will try extracting og:title
from a webpage
.
Capturing group must be an indication that it's used somewhere in the code. Any group that is not used must be non capturing.
Don't capture id attribute name here since you can't use it for anything anyway.
Correct:
r'(?:id|ID)=(?P<id>\d+)'
Incorrect:
r'(id|ID)=(?P<id>\d+)'
When using regular expressions try to write them fuzzy, relaxed and flexible, skipping insignificant parts that are more likely to change, allowing both single and double quotes for quoted values and so on.
Say you need to extract title
from the following HTML code:
<span style="position: absolute; left: 910px; width: 90px; float: right; z-index: 9999;" class="title">some fancy title</span>
The code for that task should look similar to:
title = self._search_regex(
r'<span[^>]+class="title"[^>]*>([^<]+)', webpage, 'title')
Or even better:
title = self._search_regex(
r'<span[^>]+class=(["\'])title\1[^>]*>(?P<title>[^<]+)',
webpage, 'title', group='title')
Note how you tolerate potential changes in the style
attribute's value or switch from using double quotes to single for class
attribute:
The code definitely should not look like:
title = self._search_regex(
r'<span style="position: absolute; left: 910px; width: 90px; float: right; z-index: 9999;" class="title">(.*?)</span>',
webpage, 'title', group='title')
There is a soft limit to keep lines of code under 80 characters long. This means it should be respected if possible and if it does not make readability and code maintenance worse.
For example, you should never split long string literals like URLs or some other often copied entities over multiple lines to fit this limit:
Correct:
'https://www.youtube.com/watch?v=FqZTN594JQw&list=PLMYEtVRpaqY00V9W81Cwmzp6N6vZqfUKD4'
Incorrect:
'https://www.youtube.com/watch?v=FqZTN594JQw&list='
'PLMYEtVRpaqY00V9W81Cwmzp6N6vZqfUKD4'
Extracting variables is acceptable for reducing code duplication and improving readability of complex expressions. However, you should avoid extracting variables used only once and moving them to opposite parts of the extractor file, which makes reading the linear flow difficult.
Correct:
title = self._html_search_regex(r'<title>([^<]+)</title>', webpage, 'title')
Incorrect:
TITLE_RE = r'<title>([^<]+)</title>'
# ...some lines of code...
title = self._html_search_regex(TITLE_RE, webpage, 'title')
Multiple fallback values can quickly become unwieldy. Collapse multiple fallback values into a single expression via a list of patterns.
Good:
description = self._html_search_meta(
['og:description', 'description', 'twitter:description'],
webpage, 'description', default=None)
Unwieldy:
description = (
self._og_search_description(webpage, default=None)
or self._html_search_meta('description', webpage, default=None)
or self._html_search_meta('twitter:description', webpage, default=None))
Methods supporting list of patterns are: _search_regex
, _html_search_regex
, _og_search_property
, _html_search_meta
.
Always move trailing parentheses after the last argument.
Correct:
lambda x: x['ResultSet']['Result'][0]['VideoUrlSet']['VideoUrl'],
list)
Incorrect:
lambda x: x['ResultSet']['Result'][0]['VideoUrlSet']['VideoUrl'],
list,
)
Wrap all extracted numeric data into safe functions from youtube_dl/utils.py
: int_or_none
, float_or_none
. Use them for string to number conversions as well.
Use url_or_none
for safe URL processing.
Use try_get
for safe metadata extraction from parsed JSON.
Use unified_strdate
for uniform upload_date
or any YYYYMMDD
meta field extraction, unified_timestamp
for uniform timestamp
extraction, parse_filesize
for filesize
extraction, parse_count
for count meta fields extraction, parse_resolution
, parse_duration
for duration
extraction, parse_age_limit
for age_limit
extraction.
Explore youtube_dl/utils.py
for more useful convenience functions.
description = try_get(