API

YouTube Object

class pytube.YouTube(url=None, defer_prefetch_init=False, on_progress_callback=None, on_complete_callback=None, proxies=None)[source]

Core developer interface for pytube.

captions

Interface to query caption tracks.

Return type:CaptionQuery.
description

Get the video description.

Return type:str
init()[source]

Descramble the stream data and build Stream instances.

The initialization process takes advantage of Python’s “call-by-reference evaluation,” which allows dictionary transforms to be applied in-place, instead of holding references to mutations at each interstitial step.

Return type:None
initialize_caption_objects()[source]

Populate instances of Caption.

Take the unscrambled player response data, and use it to initialize instances of Caption.

Return type:None
initialize_stream_objects(fmt)[source]

Convert manifest data to instances of Stream.

Take the unscrambled stream data and uses it to initialize instances of Stream for each media stream.

Parameters:fmt (str) – Key in stream manifest (ytplayer_config) containing progressive download or adaptive streams (e.g.: url_encoded_fmt_stream_map or adaptive_fmts).
Return type:None
length

Get the video length in seconds.

Return type:str
prefetch()[source]

Eagerly download all necessary data.

Eagerly executes all necessary network requests so all other operations don’t does need to make calls outside of the interpreter which blocks for long periods of time.

Return type:None
prefetch_init()[source]

Download data, descramble it, and build Stream instances.

Return type:None
rating

Get the video average rating.

Return type:str
register_on_complete_callback(func)[source]

Register a download complete callback function post initialization.

Parameters:func (callable) – A callback function that takes stream and file_handle.
Return type:None
register_on_progress_callback(func)[source]

Register a download progress callback function post initialization.

Parameters:func (callable) – A callback function that takes stream, chunk, file_handle, bytes_remaining as parameters.
Return type:None
streams

Interface to query both adaptive (DASH) and progressive streams.

Return type:StreamQuery.
thumbnail_url

Get the thumbnail url image.

Return type:str
title

Get the video title.

Return type:str
views

Get the number of the times the video has been viewed.

Return type:str

Stream Object

class pytube.Stream(stream, player_config_args, monostate)[source]

Container for stream manifest data.

default_filename

Generate filename based on the video title.

Return type:str
Returns:An os file system compatible filename.
download(output_path=None, filename=None, filename_prefix=None)[source]

Write the media stream to disk.

Parameters:
  • output_path (str or None) – (optional) Output path for writing media file. If one is not specified, defaults to the current working directory.
  • filename (str or None) – (optional) Output filename (stem only) for writing media file. If one is not specified, the default filename is used.
  • filename_prefix (str or None) – (optional) A string that will be prepended to the filename. For example a number in a playlist or the name of a series. If one is not specified, nothing will be prepended This is seperate from filename so you can use the default filename but still add a prefix.
Return type:

str

filesize

File size of the media stream in bytes.

Return type:int
Returns:Filesize (in bytes) of the stream.
includes_audio_track

Whether the stream only contains audio.

Return type:bool
includes_video_track

Whether the stream only contains video.

Return type:bool
is_adaptive

Whether the stream is DASH.

Return type:bool
is_progressive

Whether the stream is progressive.

Return type:bool
on_complete(file_handle)[source]

On download complete handler function.

Parameters:file_handle (io.BufferedWriter) – The file handle where the media is being written to.
Return type:None
on_progress(chunk, file_handler, bytes_remaining)[source]

On progress callback function.

This function writes the binary data to the file, then checks if an additional callback is defined in the monostate. This is exposed to allow things like displaying a progress bar.

Parameters:
  • chunk (str) – Segment of media file binary data, not yet written to disk.
  • file_handler (io.BufferedWriter) – The file handle where the media is being written to.
  • bytes_remaining (int) – The delta between the total file size in bytes and amount already downloaded.
Return type:

None

parse_codecs()[source]

Get the video/audio codecs from list of codecs.

Parse a variable length sized list of codecs and returns a constant two element tuple, with the video codec as the first element and audio as the second. Returns None if one is not available (adaptive only).

Return type:tuple
Returns:A two element tuple with audio and video codecs.
set_attributes_from_dict(dct)[source]

Set class attributes from dictionary items.

Return type:None
stream_to_buffer()[source]

Write the media stream to buffer

Return type:io.BytesIO buffer
title

Get title of video

Return type:str
Returns:Youtube video title

StreamQuery Object

class pytube.query.StreamQuery(fmt_streams)[source]

Interface for querying the available media streams.

all()[source]

Get all the results represented by this query as a list.

Return type:list
asc()[source]

Sort streams in ascending order.

Return type:StreamQuery
count()[source]

Get the count the query would return.

Return type:int
desc()[source]

Sort streams in descending order.

Return type:StreamQuery
filter(fps=None, res=None, resolution=None, mime_type=None, type=None, subtype=None, file_extension=None, abr=None, bitrate=None, video_codec=None, audio_codec=None, only_audio=None, only_video=None, progressive=None, adaptive=None, custom_filter_functions=None)[source]

Apply the given filtering criterion.

Parameters:
  • fps (int or None) – (optional) The frames per second.
  • resolution (str or None) – (optional) Alias to res.
  • res (str or None) – (optional) The video resolution.
  • mime_type (str or None) – (optional) Two-part identifier for file formats and format contents composed of a “type”, a “subtype”.
  • type (str or None) – (optional) Type part of the mime_type (e.g.: audio, video).
  • subtype (str or None) – (optional) Sub-type part of the mime_type (e.g.: mp4, mov).
  • file_extension (str or None) – (optional) Alias to sub_type.
  • abr (str or None) – (optional) Average bitrate (ABR) refers to the average amount of data transferred per unit of time (e.g.: 64kbps, 192kbps).
  • bitrate (str or None) – (optional) Alias to abr.
  • video_codec (str or None) – (optional) Video compression format.
  • audio_codec (str or None) – (optional) Audio compression format.
  • progressive (bool) – Excludes adaptive streams (one file contains both audio and video tracks).
  • adaptive (bool) – Excludes progressive streams (audio and video are on separate tracks).
  • only_audio (bool) – Excludes streams with video tracks.
  • only_video (bool) – Excludes streams with audio tracks.
  • custom_filter_functions (list or None) – (optional) Interface for defining complex filters without subclassing.
first()[source]

Get the first Stream in the results.

Return type:Stream or None
Returns:the first result of this query or None if the result doesn’t contain any streams.
get_by_itag(itag)[source]

Get the corresponding Stream for a given itag.

Parameters:int itag (str) – YouTube format identifier code.
Return type:Stream or None
Returns:The Stream matching the given itag or None if not found.
last()[source]

Get the last Stream in the results.

Return type:Stream or None
Returns:Return the last result of this query or None if the result doesn’t contain any streams.
order_by(attribute_name)[source]

Apply a sort order to a resultset.

Parameters:attribute_name (str) – The name of the attribute to sort by.

Caption Object

class pytube.Caption(caption_track)[source]

Container for caption tracks.

float_to_srt_time_format(d)[source]

Convert decimal durations into proper srt format.

Return type:str
Returns:SubRip Subtitle (str) formatted time duration.
>>> float_to_srt_time_format(3.89)
'00:00:03,890'
generate_srt_captions()[source]

Generate “SubRip Subtitle” captions.

Takes the xml captions from xml_captions() and recompiles them into the “SubRip Subtitle” format.

xml_caption_to_srt(xml_captions)[source]

Convert xml caption tracks to “SubRip Subtitle (srt)”.

Parameters:xml_captions (str) – XML formatted caption tracks.
xml_captions

Download the xml caption tracks.

CaptionQuery Object

class pytube.query.CaptionQuery(captions)[source]

Interface for querying the available captions.

all()[source]

Get all the results represented by this query as a list.

Return type:list
get_by_language_code(lang_code)[source]

Get the Caption for a given lang_code.

Parameters:lang_code (str) – The code that identifies the caption language.
Return type:Caption or None
Returns:The Caption matching the given lang_code or None if it does not exist.

Extract

This module contains all non-cipher related data extraction logic.

pytube.extract.get_ytplayer_config(html, age_restricted=False)[source]

Get the YouTube player configuration data from the watch html.

Extract the ytplayer_config, which is json data embedded within the watch html and serves as the primary source of obtaining the stream manifest data.

Parameters:
  • watch_html (str) – The html contents of the watch page.
  • age_restricted (bool) – Is video age restricted.
Return type:

str

Returns:

Substring of the html containing the encoded manifest data.

pytube.extract.is_age_restricted(watch_html)[source]

Check if content is age restricted.

Parameters:watch_html (str) – The html contents of the watch page.
Return type:bool
Returns:Whether or not the content is age restricted.
pytube.extract.js_url(html, age_restricted=False)[source]

Get the base JavaScript url.

Construct the base JavaScript url, which contains the decipher “transforms”.

Parameters:
  • watch_html (str) – The html contents of the watch page.
  • age_restricted (bool) – Is video age restricted.
pytube.extract.mime_type_codec(mime_type_codec)[source]

Parse the type data.

Breaks up the data in the type key of the manifest, which contains the mime type and codecs serialized together, and splits them into separate elements.

Example:

>>> mime_type_codec('audio/webm; codecs="opus"')
('audio/webm', ['opus'])
Parameters:mime_type_codec (str) – String containing mime type and codecs.
Return type:tuple
Returns:The mime type and a list of codecs.
pytube.extract.video_id(url)[source]

Extract the video_id from a YouTube url.

This function supports the following patterns:

  • https://youtube.com/watch?v=video_id
  • https://youtube.com/embed/video_id
  • https://youtu.be/video_id
Parameters:url (str) – A YouTube url containing a video id.
Return type:str
Returns:YouTube video id.
pytube.extract.video_info_url(video_id, watch_url, watch_html, embed_html, age_restricted)[source]

Construct the video_info url.

Parameters:
  • video_id (str) – A YouTube video identifier.
  • watch_url (str) – A YouTube watch url.
  • watch_html (str) – The html contents of the watch page.
  • embed_html (str) – The html contents of the embed page (for age restricted videos).
  • age_restricted (bool) – Is video age restricted.
Return type:

str

Returns:

https://youtube.com/get_video_info with necessary GET parameters.

pytube.extract.watch_url(video_id)[source]

Construct a sanitized YouTube watch url, given a video id.

Parameters:video_id (str) – A YouTube video identifier.
Return type:str
Returns:Sanitized YouTube watch url.

Cipher

This module countains all logic necessary to decipher the signature.

YouTube’s strategy to restrict downloading videos is to send a ciphered version of the signature to the client, along with the decryption algorithm obfuscated in JavaScript. For the clients to play the videos, JavaScript must take the ciphered version, cycle it through a series of “transform functions,” and then signs the media URL with the output.

This module is responsible for (1) finding and extracting those “transform functions” (2) maps them to Python equivalents and (3) taking the ciphered signature and decoding it.

pytube.cipher.get_initial_function_name(js)[source]

Extract the name of the function responsible for computing the signature.

Parameters:js (str) – The contents of the base.js asset file.
pytube.cipher.get_signature(js, ciphered_signature)[source]

Decipher the signature.

Taking the ciphered signature, applies the transform functions.

Parameters:
  • js (str) – The contents of the base.js asset file.
  • ciphered_signature (str) – The ciphered signature sent in the player_config.
Return type:

str

Returns:

Decrypted signature required to download the media content.

pytube.cipher.get_transform_map(js, var)[source]

Build a transform function lookup.

Build a lookup table of obfuscated JavaScript function names to the Python equivalents.

Parameters:
  • js (str) – The contents of the base.js asset file.
  • var (str) – The obfuscated variable name that stores an object with all functions that descrambles the signature.
pytube.cipher.get_transform_object(js, var)[source]

Extract the “transform object”.

The “transform object” contains the function definitions referenced in the “transform plan”. The var argument is the obfuscated variable name which contains these functions, for example, given the function call DE.AJ(a,15) returned by the transform plan, “DE” would be the var.

Parameters:
  • js (str) – The contents of the base.js asset file.
  • var (str) – The obfuscated variable name that stores an object with all functions that descrambles the signature.

Example:

>>> get_transform_object(js, 'DE')
['AJ:function(a){a.reverse()}',
'VR:function(a,b){a.splice(0,b)}',
'kT:function(a,b){var c=a[0];a[0]=a[b%a.length];a[b]=c}']
pytube.cipher.get_transform_plan(js)[source]

Extract the “transform plan”.

The “transform plan” is the functions that the ciphered signature is cycled through to obtain the actual signature.

Parameters:js (str) – The contents of the base.js asset file.

Example:

>>> get_transform_plan(js)
['DE.AJ(a,15)',
'DE.VR(a,3)',
'DE.AJ(a,51)',
'DE.VR(a,3)',
'DE.kT(a,51)',
'DE.kT(a,8)',
'DE.VR(a,3)',
'DE.kT(a,21)']
pytube.cipher.map_functions(js_func)[source]

For a given JavaScript transform function, return the Python equivalent.

Parameters:js_func (str) – The JavaScript version of the transform function.
pytube.cipher.parse_function(js_func)[source]

Parse the Javascript transform function.

Break a JavaScript transform function down into a two element tuple containing the function name and some integer-based argument.

Parameters:js_func (str) – The JavaScript version of the transform function.
Return type:tuple
Returns:two element tuple containing the function name and an argument.

Example:

>>> parse_function('DE.AJ(a,15)')
('AJ', 15)
pytube.cipher.reverse(arr, b)[source]

Reverse elements in a list.

This function is equivalent to:

function(a, b) { a.reverse() }

This method takes an unused b variable as their transform functions universally sent two arguments.

Example:

>>> reverse([1, 2, 3, 4])
[4, 3, 2, 1]
pytube.cipher.splice(arr, b)[source]

Add/remove items to/from a list.

This function is equivalent to:

function(a, b) { a.splice(0, b) }

Example:

>>> splice([1, 2, 3, 4], 2)
[1, 2]
pytube.cipher.swap(arr, b)[source]

Swap positions at b modulus the list length.

This function is equivalent to:

function(a, b) { var c=a[0];a[0]=a[b%a.length];a[b]=c }

Example:

>>> swap([1, 2, 3, 4], 2)
[3, 2, 1, 4]

Exceptions

Library specific exception definitions.

exception pytube.exceptions.ExtractError(msg, video_id=None)[source]

Data extraction based exception.

exception pytube.exceptions.LiveStreamError(msg, video_id=None)[source]

Video is a live stream.

exception pytube.exceptions.PytubeError[source]

Base pytube exception that all others inherent.

This is done to not pollute the built-in exceptions, which could result in unintended errors being unexpectedly and incorrectly handled within implementers code.

exception pytube.exceptions.RegexMatchError(msg, video_id=None)[source]

Regex pattern did not return any matches.

exception pytube.exceptions.VideoUnavailable[source]

Video is unavailable.

Mixins

Applies in-place data mutations.

pytube.mixins.apply_descrambler(stream_data, key)[source]

Apply various in-place transforms to YouTube’s media stream data.

Creates a list of dictionaries by string splitting on commas, then taking each list item, parsing it as a query string, converting it to a dict and unquoting the value.

Parameters:
  • dct (dict) – Dictionary containing query string encoded values.
  • key (str) – Name of the key in dictionary.

Example:

>>> d = {'foo': 'bar=1&var=test,em=5&t=url%20encoded'}
>>> apply_descrambler(d, 'foo')
>>> print(d)
{'foo': [{'bar': '1', 'var': 'test'}, {'em': '5', 't': 'url encoded'}]}
pytube.mixins.apply_signature(config_args, fmt, js)[source]

Apply the decrypted signature to the stream manifest.

Parameters:
  • config_args (dict) – Details of the media streams available.
  • fmt (str) – Key in stream manifests (ytplayer_config) containing progressive download or adaptive streams (e.g.: url_encoded_fmt_stream_map or adaptive_fmts).
  • js (str) – The contents of the base.js asset file.

Compat

Python 2/3 compatibility support.

pytube.compat.install_proxy(proxy_handler)[source]

install global proxy. :param proxy_handler:

“http”:”http://my.proxy.com:1234”, “https”:”https://my.proxy.com:1234”
Returns:
pytube.compat.unescape(s)[source]

Strip HTML entries from a string.

pytube.compat.unicode(s)[source]

Encode a string to utf-8.

Helpers

Various helper functions implemented by pytube.

pytube.helpers.apply_mixin(dct, key, func, *args, **kwargs)[source]

Apply in-place data mutation to a dictionary.

Parameters:
  • dct (dict) – Dictionary to apply mixin function to.
  • key (str) – Key within dictionary to apply mixin function to.
  • func (callable) – Transform function to apply to dct[key].
  • *args – (optional) positional arguments that func takes.
  • **kwargs – (optional) keyword arguments that func takes.
Return type:

None

Shortcut method to search a string for a given pattern.

Parameters:
  • pattern (str) – A regular expression pattern.
  • string (str) – A target string to search.
  • groups (bool) – Should the return value be .groups().
  • group (int) – Index of group to return.
  • flags (int) – Expression behavior modifiers.
Return type:

str or tuple

Returns:

Substring pattern matches.

pytube.helpers.safe_filename(s, max_length=255)[source]

Sanitize a string making it safe to use as a filename.

This function was based off the limitations outlined here: https://en.wikipedia.org/wiki/Filename.

Parameters:
  • s (str) – A string to make safe for use as a file name.
  • max_length (int) – The maximum filename character length.
Return type:

str

Returns:

A sanitized string.

Request

Implements a simple wrapper around urlopen.

pytube.request.get(url=None, headers=False, streaming=False, chunk_size=8192)[source]

Send an http GET request.

Parameters:
  • url (str) – The URL to perform the GET request for.
  • headers (bool) – Only return the http headers.
  • streaming (bool) – Returns the response body in chunks via a generator.
  • chunk_size (int) – The size in bytes of each chunk.
pytube.request.stream_response(response, chunk_size=8192)[source]

Read the response in chunks.