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 a formatting operations. Allowed names along
-with sequence type are:
+parentheses, followed by formatting operations. Allowed names along with
+sequence type are:
- id (string): Video identifier
- title (string): Video title
available
- upload_date (string): Video upload date (YYYYMMDD)
- uploader_id (string): Nickname or id of the video uploader
+- channel (string): Full name of the channel the video is uploaded on
+- channel_id (string): Id of the channel
- location (string): Physical location where the video was filmed
- duration (numeric): Length of the video in seconds
- view_count (numeric): How many users have watched the video on the
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.
+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.
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 advance - width: Width of the video, if known - height: Height
-of the video, if known - tbr: Average bitrate of audio and video in
-KBit/s - abr: Average audio bitrate in KBit/s - vbr: Average video
-bitrate in KBit/s - asr: Audio sampling rate in Hertz - fps: Frame rate
-
-Also filtering work for comparisons = (equals), != (not equals), ^=
-(begins with), $= (ends with), *= (contains) and following string meta
-fields: - ext: File extension - acodec: Name of the audio codec in use -
-vcodec: Name of the video codec in use - container: Name of the
-container format - protocol: The protocol that will be used for the
-actual download, lower-case (http, https, rtsp, rtmp, rtmpe, mms, f4m,
-ism, http_dash_segments, m3u8, or m3u8_native) - format_id: A short
-description of the format
+>=, = (equals), != (not equals):
+
+- filesize: The number of bytes, if known in advance
+- width: Width of the video, if known
+- height: Height of the video, if known
+- tbr: Average bitrate of audio and video in KBit/s
+- abr: Average audio bitrate in KBit/s
+- vbr: Average video bitrate in KBit/s
+- asr: Audio sampling rate in Hertz
+- fps: Frame rate
+
+Also filtering work for comparisons = (equals), ^= (starts with), $=
+(ends with), *= (contains) and following string meta fields:
+
+- ext: File extension
+- acodec: Name of the audio codec in use
+- vcodec: Name of the video codec in use
+- container: Name of the container format
+- protocol: The protocol that will be used for the actual download,
+ lower-case (http, https, rtsp, rtmp, rtmpe, mms, f4m, ism,
+ http_dash_segments, m3u8, or m3u8_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
# 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 not better that 480p
+ # 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
methods and a detailed description of what your extractor should and
may return. Add tests and code for as many as you want.
8. Make sure your code follows youtube-dl coding conventions and check
- the code with flake8. Also make sure your code works under all
- Python versions claimed supported by youtube-dl, namely 2.6, 2.7,
- and 3.2+.
-9. When the tests pass, add the new files and commit them and push the
+ the code with flake8:
+
+ $ flake8 youtube_dl/extractor/yourextractor.py
+
+9. Make sure your code works under all Python versions claimed
+ supported by youtube-dl, namely 2.6, 2.7, and 3.2+.
+10. 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
+ $ 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
-10. Finally, create a pull request. We'll then review and merge it.
+11. Finally, create a pull request. We'll then review and merge it.
In any case, thank you very much for your contributions!
This code will try to extract from meta first and if it fails it will
try extracting og:title from a webpage.
-Make regular expressions flexible
+Regular expressions
+
+Don't capture groups you don't use
+
+Capturing group must be an indication that it's used somewhere in the
+code. Any group that is not used must be non capturing.
+
+Example
+
+Don't capture id attribute name here since you can't use it for anything
+anyway.
-When using regular expressions try to write them fuzzy and flexible.
+Correct:
+
+ r'(?:id|ID)=(?P<id>\d+)'
+
+Incorrect:
+
+ r'(id|ID)=(?P<id>\d+)'
+
+Make regular expressions relaxed and flexible
+
+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.
Example
r'<span style="position: absolute; left: 910px; width: 90px; float: right; z-index: 9999;" class="title">(.*?)</span>',
webpage, 'title', group='title')
-Use safe conversion functions
+Long lines policy
+
+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'
+
+Use convenience conversion and parsing functions
+
+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.
+
+More examples
+
+Safely extract optional description from parsed JSON
+
+ description = try_get(response, lambda x: x['result']['video'][0]['summary'], compat_str)
+
+Safely extract more optional metadata
-Wrap all extracted numeric data into safe functions from utils:
-int_or_none, float_or_none. Use them for string to number conversions as
-well.
+ video = try_get(response, lambda x: x['result']['video'][0], dict) or {}
+ description = video.get('summary')
+ duration = float_or_none(video.get('durationMs'), scale=1000)
+ view_count = int_or_none(video.get('views'))
Bugs and suggestions should be reported at:
-https://github.com/rg3/youtube-dl/issues. Unless you were prompted to or
-there is another pertinent reason (e.g. GitHub fails to accept the bug
-report), please do not send bug reports via personal email. For
+https://github.com/ytdl-org/youtube-dl/issues. Unless you were prompted
+to or there is another pertinent reason (e.g. GitHub fails to accept the
+bug report), please do not send bug reports via personal email. For
discussions, join us in the IRC channel #youtube-dl on freenode
(webchat).
Rapsys Git / youtubedl / blobdiff