Podcast Downloader

The Python module designed for downloading files from given RSS feeds, particularly targeted at podcasts. It does not use any sort of database but requires a configuration file.

The script is intended to be run periodically. Upon starting, it analyzes the directory where it previously stored downloaded files. It then compares these files with those listed in the RSS feed, identifying any missing ones and downloading them.

The files searched by default are mp3.

The result of using the example below, on empty directories, will be:

dplocki@ghost-wheel:~$ python -m podcast_downloader
[2024-04-08 21:19:10] Loading configuration (from file: "~/.podcast_downloader_config.json")
[2024-04-08 21:19:15] Checking "The Skeptic Guide"
[2024-04-08 21:19:15] Last downloaded file "<none>"
[2024-04-08 21:19:15] The Skeptic Guide: Downloading file: "https://traffic.libsyn.com/secure/skepticsguide/skepticast2024-04-06.mp3" saved as "skepticast2024-04-06.mp3"
[2024-04-08 21:19:41] Checking "The Real Python Podcast"
[2024-04-08 21:19:41] Last downloaded file "<none>"
[2024-04-08 21:19:41] The Real Python Podcast: Downloading file: "https://chtbl.com/track/92DB94/files.realpython.com/podcasts/RPP_E199_03_Calvin.eef1db4d6679.mp3" saved as "[20240405] rpp_e199_03_calvin.eef1db4d6679.mp3"
[2024-04-08 21:20:04] Finished

The result:

dplocki@ghost-wheel:~$ tree podcasts/
podcasts/
├── RealPython
│   └── [20240405] rpp_e199_03_calvin.eef1db4d6679.mp3
└── SGTTU
    └── skepticast2024-04-06.mp3

2 directories, 2 files

Setup

Installation from PyPI:

pip install podcast_downloader

Running the script

The script requires configuration file in order to work. After installation, the script can be run as any Python module:

python -m podcast_downloader

It is also possible to run the script with given configuration file:

python -m podcast_downloader --config my_config.json

Configuration

An example of configuration file

{
  "if_directory_empty": "download_from_4_days",
  "podcasts": [
    {
      "name": "The Skeptic Guide",
      "rss_link": "https://feed.theskepticsguide.org/feed/rss.aspx",
      "path": "~/podcasts/SGTTU"
    },
    {
      "rss_link": "https://realpython.com/podcasts/rpp/feed",
      "path": "~/podcasts/RealPython",
      "file_name_template": "[%publish_date%] %file_name%.%file_extension%"
    }
  ]
}

The configuration file

By default the configuration file is placed in home directory. It's file name is: .podcast_downloader_config.json.

The config file is format in JSON. The expected encoding is utf-8.

The path to configuration file can be specified by script argument.

The settings hierarchy

The script replaces default values by those read from configuration file. Those will be overload by values given from command line.

command line parameters > configuration file > default values

The main options

Property	Type	Required?	Default	Note
downloads_limit	number	no	infinity
if_directory_empty	string	no	download_last	See In case of empty directory
podcast_extensions	key-value	no	{".mp3": "audio/mpeg"}	See File types filter
podcasts	subsection	yes	[]	See Podcasts sub category
http_headers	key-value	no	{"User-Agent": "podcast-downloader"}	See HTTP request headers
fill_up_gaps	boolean	no	false	See Download files from gaps
download_delay	number	no	0	See Download delay

Podcasts sub category

The podcasts segment is the part of configuration file where you provide the array of objects with fallowing content:

Property	Type	Required	Default	Note
name	string	yes	-	The name of channel (use in logger)
rss_link	string	yes	-	The URL of RSS feed
path	string	yes	-	The path to directory, where podcast are stored, will be downloaded
file_name_template	string	no	%file_name%.%file_extension%	The template for the downloaded files, see File name template
disable	boolean	no	false	This podcast will be ignored
podcast_extensions	key-value	no	{".mp3": "audio/mpeg"}	The file filter
if_directory_empty	string	no	download_last	See In case of empty directory
require_date	boolean	no	false	Deprecated Is date of podcast should be added into name of file - use the file_name_template: [%publish_date%] %file_name%.%file_extension%"
http_headers	key-value	no	{"User-Agent": "podcast-downloader"}	See HTTP request headers
fill_up_gaps	boolean	no	false	See Download files from gaps

HTTP request headers

Some servers may not like how the urllib is presenting itself to them (the HTTP User-Agent header). This may lead into problems like: urllib.error.HTTPError: HTTP Error 403: Forbidden. That is why, there is a possibility for the script to pose as something else: by specifying the HTTP headers during downloading files.

Use the http_headers option in the configuration file. The value should be a dictionary object where each header is presented as a key-value pair. The key being the header title and the value being the header value.

By default the value is: {"User-Agent": "podcast-downloader"}. Providing anything else for http_headers will override all the default values (they do not merge).

On other hand in the podcast sub-configuration, the http_headers will be merged with the global http_headers. In case of a conflict (same key name), the vale from podcast sub-configuration will override the global one.

Example:

{
  "http_headers": {
    "User-Agent": "podcast-downloader"

  },
  "podcasts": [
    {
      "name": "Unua Podcast",
      "rss_link": "http://www.unuapodcast.org/feed.rss",
      "path": "~/podcasts/unua_podcast",
      "https_headers": {
        "User-Agent": "Mozilla/5.0"
      }
    },
    {
      "name": "Dua Podcast",
      "rss_link": "http://www.duapodcast.org/feed.rss",
      "path": "~/podcasts/dua_podcast",
      "https_headers": {
        "Authorization": "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
      }
    }
  ]
}

In this example, the Unua Podcast will be download just with the header: User-Agent: Mozilla/5.0, and the Dua Podcast with: User-Agent: podcast-downloader and Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==.

Download delay

When you had a lot of files to download from a single server, it may be better to set up the small delay between downloads to avoid being recognized as an attacker by the server. In the script there is an option called download_delay, which represents the number of seconds the script will wait between downloads.

The default value is 0.

Notes:

• this delay applies per podcast, not between two different podcasts
• the value can be provided as script argument

Script arguments

The script accepts following command line arguments:

Short version	Long name	Parameter	Default	Note
	--config	string	~/.podcast_downloader_config.json	The placement of the configuration file
	--downloads_limit	number	infinity	The maximum number of downloaded mp3 files
	--if_directory_empty	string	download_last	The general approach on empty directory
	--download_delay	number	0	The waiting time (seconds) between downloads

File name template

Use to adjust the file name after downloading.

Default value (the %file_name%.%file_extension%) will simple save up the file as it was uploaded by original creator. The file name and its extension is based on the link to podcast file.

Template values:

Name	Notes
%file_name%	The file name from the link, without extension
%file_extension%	The extension for the file, from link
%publish_date%	The publish date of the RSS entry
%title%	The title of the RSS entry

Non-default the publish_date

The %publish_date% by default gives result in format YEARMMDD. In order to change it you can provide the new one after the colon (the : character). The script respect the codes of the 1989 C standard, but the percent sign (%) must be replaced by dollar sign ($). This is because of my unfortunate decision to use the percent character as marker of the code.

The standard code	The script code	Notes
%Y%m%d	$Y$m$d	The default value of the %publish_date%
%A	$A	Adds the weekday (local language settings)
%x	$x	The local date represent. Warning: in some settings, the / is used here, so it may caused problem in the file name

Examples

• [%publish_date%] %file_name%.%file_extension%
• [%publish_date%] %title%.%file_extension%

File types filter

Podcasts are mostly stored as *.mp3 files. By default Podcast Downloader looks just for them, ignoring all others types.

If your podcast supports other types of media files, you can specified the file filters. Provide the extension of the file (like .mp3) and type of link in RSS feed itself (for mp3 it is audio/mpeg).

If you don't know the type of the file, you can look for it in the RSS file. Seek for enclosure tags, should looks like this:

  <enclosure url="https://www.vidocast.url/podcast/episode23.m4a"
             length="14527149"
             type="audio/x-m4a" />

Note: the dot on the file extension is require.

Example

  "podcast_extensions": {
    ".mp3": "audio/mpeg",
    ".m4a": "audio/x-m4a"
  }

In case of empty directory

If a directory for podcast is empty, the script needs to know what to do. Due to lack of database, you can:

• download all episodes from feed
• download only the last episode
• download last n episodes
• download all new episode from last n days
• download all new episode since day after, the last episode should appear
• download all the new, since the last run

Default behavior is: download_last

Download all from feed

The script will download all episodes from the feed.

Set by download_all_from_feed.

Download last

The script will download only the last episode from the feed. It is also default approach of the script.

Set by download_last.

Download last n episodes

The script will download exactly the given number of episodes from the feed.

Set by download_last_n_episodes. The n must be replaced by a number of episodes, which you wanted to have downloaded. For example: download_last_5_episodes means that five most recent episodes will be downloaded.

Download all from n days

The script will download all episodes which appear in recent n days. It can be use when you are downloading on regular schedule. The n number is given within the setup value: download_from_n_days. For example: download_from_3_days means download all episodes from last 3 days.

Download all episode since last excepted

The script will download all episodes which appear after the day of release of last episode.

The n number is the day of the normal episode. You can provide here week days as word (size of the letters is ignored)

Full week day	Shorten name
Monday	Mon
Tuesday	Tues
Wednesday	Weds
Thursday	Thurs
Friday	Fri
Saturday	Sat
Sunday	Sun

You can provide the number, it will means the day of the month. The script accepts only number from 1 to 28.

Set by download_from_.

Examples:

Example value	Meaning
download_from_monday	New episodes appear in Monday. The script will download all episodes since last Tuesday (including it)
download_from_Fri	New episodes appear in Friday. The script will download all episodes since last Saturday (including it)
download_from_12	New episodes appear each 12th of month. The script will download all episodes since 13 month before

Download all new, since the last run

Once you establish the totem file, the script can use it to store the date of its last run. Then, based on this date, the script will download all new episodes that have appeared since then.

Set by download_since_last_run. Requires establish the store file by last_run_mark_file_path.

Example:

{
  "last_run_mark_file_path": "~/.totem.json",
  "podcasts": [
    {
      "name": "The Skeptic Guide",
      "rss_link": "https://feed.theskepticsguide.org/feed/rss.aspx",
      "path": "~/podcasts/SGTTU"
    }
  ]
}

The last run mark file

The script is reading the date of last modification of the file. The file's modification date is updated by the script.

Download files from gaps

The script recognizes the stream of downloaded files (based on the feed data). By default, the last downloaded file (according to the feed) marks the start of downloading. In case of gaps, situation where there are missing files before the last downloaded one, the script will ignore them by default. However, there is a possibility to change this behavior to download all missing files between already downloaded ones. To enable this, you need to set the fill_up_gaps value to true. It's important to note that the script will not download files before the first one (according to the feed), the most earlier episode.

Default value: false.

The analyze of the RSS feed

The script looks through all the items nodes in RSS file. The item node can contain the enclosure node. Those nodes are used to passing the files. According to the convention the single item should contain only one enclosure, but script (as the library used under it) can handle the multiple files attached into podcast item.

Converting the OPML

The OPML files can be converted into configuration. The output file needs to be adjusted (missing the path).

import json
import sys
import xml.etree.ElementTree as ET


def build_podcast(node_rss):
    return {
        "name": node_rss.attrib["title"],
        "rss_link": node_rss.attrib["xmlUrl"],
        "path": "",
    }


tree = ET.parse(sys.argv[1])
podcasts = list(map(build_podcast, tree.findall("body/outline[@type='rss']")))
result = json.dumps({"podcasts": podcasts}, sort_keys=True, indent=4)

print(result)

Example of usage (after saving it as opml_converter.py):

python opml_converter.py example.opml > podcast_downloader_config.json