RFC for a XML-based Podlove File Format

Version 0.1
12 Apr 2012

By Sebastian Lammermann
sebastian@lammermann.eu
http://www.lammermann.eu/
@Seb1982

Published under Creative Commons Licence
CC BY 3.0
Details: http://creativecommons.org/licenses/by/3.0/

Flattr: https://flattr.com/thing/626045/Podlove-File-Format-Request-For-Change

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Request For Change

The idea of a Podlove file format had been developed by Tim Pritlove (@timpritlove) aiming at a system that improves the quality of Podcast playing as well as managing and handling. As an addict to Podcast I liked the idea from the start and began thinking about how to solve some basic issues that might appear during the development process.

As an engineer I tend to approach problems like this from the low OSI layers. I am not a programmer but I would like to help delivering a system below the actual programmes to allow developers of all kind of platforms to use a common standard and to improve interoperability. A smart phone application should process the same data as a CMS plug-in or an audio player software.

My RFC for the new standard is based on XML. The idea is to create a Podlove file for every episode containing standard information like title, description, publishing date, language and so forth. In addition I recommend adding the following tags:

* <class> Informs about the class of the episode (e. g. "audio" or "video") to ease handling for programmes
* <details> Allows the application to load further information (e. g. show notes) from an external source (like a website)
* <length> Length of the episode. A Podlove application will get this information without downloading the file
* <chapter> Additional tags containing information of chapters within the episode to allow simple skipping. The sub-tag <time> marks the position of the chapter's beginning within the episode. It is also possible to add a description and a title
* <file> If the episode exists in one format only this tag contains the path to the actual media file. If it is published in several formats (e. g. MP3, MP4 or OGG) the tag may contain all file paths divided by semicolon. It is up to the Podlove application to let you download your favourite format or something like that
* <donation> This extra tag allows to integrate donation services like Flattr. In this case the application would display a button based on the Flattr item

Now that we have added another layer between the subscribable feed and the media file the next point is to deliver the Podlove file via feed. In general I see two possible approaches.

The first is to take a regular RSS feed and link it directly to the Podlove file. This is simple but it is necessary to maintain separate files for Podlove and regular subscribers.

The second approach is to amend the feed file's <item> tag by the extra <podlove> tag which contains the link to the Podlove file - in addition to the regular path. The counterpart here is that the RSS file will not be fulfilling the official standard's criteria anymore so that intolerant programmes might not be able to process the file.

I recommend developing a Podcast management software that is based on the Podlove standard in order to make managing episodes easy and helps keeping the overview.

I would love to get feedback so please send me your comments. If anyone would like to work with me on the Podlove file format I will set up a Wiki.

Thank You!

Sebastian

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<!-- first RFC for a XML-based Podlove file format-->

<?xml version="1.0" encoding="utf-8"?>
 
<podlove version="0.1">

  <episode>
    <title>episode title</title>
    <class>audio or video</class>
    <file>file path(s) (e. g. "./folder/file.mp3" or "./folder/file.mp3;./folder/file.ogg")</file>
    <description>short description</description>
    <details>URL from where further information could be received (e. g. show notes)</details>
    <language>language of the episode (e. g. "en-us")</language>
    <copyright>author of the episode</copyright>
    <pubdate>publishing date (e. g. "Wed, 11 Apr 2012 22:05:32 +0000")</pubdate>
    <image>
      <url>image URL</url>
      <title>image title</title>
      <link>URL connected to the image</link>
    </image>
    <donation>URL for donation (e. g. Flattr item)</donation>
    <length>length of the episode (e. g. "2:23:65.810")</length>

    <chapter>
      <time>begin of the chapter within the episode, h:min:s.ms (e. g. "0:00:00.000" or "3:56:23.132")</time>
      <title>title of the chapter</title>
      <description>short description</description>
    </chapter>

  </episode>

</podlove>

<!-- Every episode get it's own XML-based Podlove file ("filename.pdl" suggested). Some tags are identical to the ones from RSS files. In addition there are:
* <class> Informs about the class of the episode (e. g. "audio" or "video")
* <file>: Path(s) to the media file(s). If the file exists in more than one format the paths are divides by semicolon. The podcast application chooses the file to load.
* <details>: Contains an URL to allow the podcast application to load further information like show notes etc.
* <donation>: Allows to add a link to a donation system like Flattr. The podcast application should display a button.
* <length>: Total length of the episode.
* <chapter>: Chapter within the file to allow skipping - including title and description. 
-->

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<!-- Regular RSS file with link to Podlove file -->

<?xml version="1.0" encoding="UTF-8" ?>

<rss version="2.0">

  <channel>
    ....

    <item>
      ....
      <link>path to Podlove file (e. g. "./folder/file.pdl")</link>
      ....
    </item>

    ....
 
  </channel>

</rss>

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<!-- Modified RSS file with additional tags -->

<?xml version="1.0" encoding="UTF-8" ?>

<rss version="2.x">

  <channel>
    ....
    <donation>URL for donations to the channel (e. g. Flattr item)</donation>

    <item>
      ....
      <link>regular media file path (e. g. "./folder/file.mp3")</link>
      <podlove>new Podlove tag that contains the file path (e. g. "./folder/file.pdl")</podlove>
      ....
    </item>

    ....
 
  </channel>

</rss>

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(The original RFC version may contain a lot of spelling mistakes. This circumstance will be ignored in order to publish this file before Friday 13th ;) )