The "podcast" Namespace

A wholistic rss namespace for podcasting that is meant to synthesize the fragmented world of podcast namespaces. The broad goal is to create a single, compact, efficient namespace that is easily extensible, community controlled/authored and addresses the needs of the independent podcast industry now and in the future. Our hope is that this namespace will become the framework that the independent podcast community needs to deliver new functionality to apps and aggregators.

Current Roadmap

Phase 1 - [Closed] Comment period closed on 11/15/20 and 5 tags were adopted.

Phase 2 - [Open] Comment period closes on 1/31/21 and tags that have good consensus will be adopted. Any tags with questions, concerns or no discernable use case will be either removed or booted to Phase 3.

Phase 3 - [Open] Proposals welcome.

Legend

Formalized - This tag is frozen and listed in the XMLNS document. Any future changes to it's definition must maintain backwards compatibility.

Finalized - The tag is structurally stable and implementation testing should be considered safe. Any breaking changes will be widely communicated.

Open - The tag/phase is open for discussion and collaboration.

Required - This tag or attribute must be present.

Optional - This tag or attribute may be left out.

Recommended - This tag or attribute is technically optional, but is strongly recommended to be present for the tag to function as fully intended.

Tag Adoption Process

To be adopted as an official part of the namespace, there must be consensus around a tag's usefulness and either commitment to adoption by at least 1 host and 1 app, or a recognition that the tag is already being used in the wild.

It is ALWAYS ok to delay a tag to a future Phase if there is any concern about it. That is to be expected and encouraged.

When a Phase comes to a close, there will be a full review of any tags currently open for comment and questions will be asked to gather consensus before final adoption. No tags will be adopted by fiat, or if there are unresolved questions. They will just be moved to the next Phase for further comment and refinement.

Tags that are proposals or rough ideas should be expected to have syntax problems or typos. Those should be refined away as they are worked on. If they are not, that is a good idea that the tag in question isn't being seen as useful and should be considered for dropping.

We are not a "standards body". It is a community driven project where all stake holders are encouraged to participate, so that many voices are heard. This is an open-source project to be built fully in the open. Discussions also take place on podcastindex.social where anyone is free to register and participate.

Goal #1 - Eliminate Redundancy

There is significant overlap amongst the many existing podcast namespaces. Each platform and publisher has created their own namespace to give their respective system and audience the metadata they need in the way they want it delivered.

Goal #2 - Keep "required" tags and attributes minimal

The only required tags should be those that solve an overwhelming need in the industry. Requiring tags is a roadblock to adoption and should be avoided. Attributes should also only be required when they are key to the functionality of the tag.

Goal #3 - Keep Exisiting Conventions

Reinventing the wheel helps nobody. When at all possible, existing conventions should be maintained. For example, it would make sense to turn <podcast:explicit> into a unary element, where it's existence is taken as a "yes" and it's absence as a "no". But, that has never been the standard. And, given as how this namespace will probably sit alongside at least one other namespace, it makes sense to keep existing conventions in place.

Goal #4 - Be General... to a point

There is no way to address every possible metadata point that each platform would want. That is not the aim. Instead we focus on defining the elements that would be useful to the broadest set of apps, publishers, platforms and aggregators. Individual parties can keep their respective supplemental namespaces small and targeted as an adjunct to this larger namespace. But, we don't want to be so general that the spec becomes overly complicated. A beautiful, "perfect" spec is not important. Solving real problems is.

The Guiding Principles

Our guiding principles for development of this namespace are the "Rules for Standards Makers" by Dave Winer. Please read it before contributing if you aren't familiar with it.

Official XMLNS Definition

To see the formalized tags, the official definition file is here.

Supporting Platforms and Apps

To see a list of platforms and apps that currently implement some or all of these tags, see the list here.

Example Feed

There is an example feed example.xml in this repository showing the podcastindex namespace side by side with the Apple itunes namespace.

Element List

Phase 1 (Closed on 11/15/20)

The following tags have been formally adopted into the namespace. They are fully documented in the XMLNS document located here. Please see that file for full implementation details.

• <podcast:locked>
  
• <podcast:transcript>
  
• <podcast:funding>
  
• <podcast:chapters>
  
• <podcast:soundbite>
  

Phase 2 (Open)

• <podcast:person (role="[host,guest,etc.]") (group="[cast,writing,etc.]") (img="[uri of content]") (href="[uri to Podchaser/website/wiki/blog]")>[name of person]</podcast:person> (finalized)

  Channel or Item (optional | multiple)

  This element specifies a person of interest to the podcast. It is primarily intended to identify people like hosts, co-hosts and guests. Although, it is flexible enough to allow fuller credits to be given using the roles and groups that are listed in the Podcast Taxonomy Project.

  • Tag Value (required) This is the full name or alias of the person.
  • role (optional) Used to identify what role the person serves on the show or episode. This should be a reference to an official role within the Podcast Taxonomy Project list (see below). If role is missing then "host" is assumed.
  • group (optional) This should be a camel-cased, alphanumeric reference to an official group within the Podcast Taxonomy Project list. If group is not present, then "cast" is assumed.
  • img (optional) This is the url of a picture or avatar of the person.
  • href (optional) The url to a relevant resource of information about the person, such as a homepage or third-party profile platform. Please see the example feed for possible choices of what to use here.

  The maximum recommended string length of each attribute value, and the tag's node value is 128 characters.

  The role and group tags are case-insensitive. So, "Host" is the same as "host".

  The full taxonomy list is here as a json file.

• <podcast:location (geo="[geoURI]") (osm="[OSM type][OSM id](#OSM revision)")>[humanly readable place name]</podcast:location> (finalized)

  Channel or Item (optional | multiple)

  This tag is intended to describe the location of editorial focus for a podcast's content - i.e. "what place is this podcast about?"

  The tag has many use cases and is one of the more complex ones. You are highly encouraged to read the full implementation document before starting to code for it.

  • Tag Value (required) This is a free-form string meant to be a human readable location. It may conform to conventional location verbiage (i.e. "Austin, TX"), but it shouldn't be depended on to be parseable in any specific way.
  • geo (recommended) This is a latitude and longitude given in "geo" notation (i.e. "geoURI:30.2672,97.7431").
  • osm (recommended) The Open Street Map identifier of this place, given using the OSM notation (i.e. "R113314")

  The maximum recommended string length of each attribute value, and the tag's node value is 128 characters.

• <podcast:season (name="[name of season]")>[(int)]</podcast:season> (finalized)

  Item

  (optional | single)

  This element allows for identifying which episodes in a podcast are part of a "season", and allowing that season to have a name associate with it, such as name="Race for the White House 2020". The element's value is an integer identifying the season number.

  All attributes are optional.

• <podcast:episode (display="[episode number to show]")>[(decimal)]</podcast:episode>

  Item

  (optional | single)

  This element exists largely for compatibility with the season tag. But, it also allows for a similar naming idea. The episode numbers are decimal, so numbering such as 100.5 is acceptable if there was a special mini-episode published between two other episodes. In this scenario, the number would help with proper chronological sorting, while the display attribute could specify an alternate number(like display="100a") to display for the episode in a podcast player app GUI.

  All attributes are optional.

• <podcast:id platform="[service slug]" id="[platform id]" url="[link to the podcast page on the service]" />

  Channel

  (optional | multiple)

  See "IDs" in this document for an explanation.

  • platform (required) This is the service slug of the platform.
  • id (required) This is the unique identifier for this podcast on the respective platform.
  • url (optional) A url to the page for this podcast on the respective platform.

• <podcast:social platform="[service slug]" url="[link to social media account]">[social media handle]</podcast:social>

  Channel or Item

  (optional | multiple)

  This element lists social media accounts for this podcast. The service slugs should be community written into the accompanying serviceslugs.txt file.

  The maximum recommended string length of the node value is 128 characters.

Phase 3 (Open)

• <podcast:category>[category Name]</podcast:category>

  Channel

  (optional | multiple)

  See "Categories" in this document for an explanation. There can be up to a total of 9 categories defined.

  There can be a maximum of 9 category elements defined in a feed. Any number greater than that should be discarded.

  Category names are defined in the accompanying "categories.json" file in this repository. They should be referenced in the element by their textual name. The characters can be in any case. This list of categories aims to replicate the current standard but also eliminate as much as possible compound, heirarchical naming and the use of ampersands. Thus, "Health & Fitness" becomes "Health" and "Fitness" as two distinct categories. And, "Religion & Spirituality" becomes two separate categories. Again, they are different things that don't always go together. Splitting them allows for more flexible combinations. And, avoiding ampersands makes xml encoding errors less likely.

• <podcast:contentRating>[rating letter]</podcast:contentRating>

  Channel or Item

  (optional | single)

  Specifies the generally accepted rating letter of G, PG, PG-13, R or X. Or, perhaps an age rating system like all, 14, 19, adult. Needs discussion.

• <podcast:previousUrl>[url this feed was imported from]</podcast:previousUrl>

  Channel

  (optional | multiple)

  Lists the previous url of this feed before it was imported. Any time a feed is moved, an additional <podcast:previousUrl> element should be added to the channel, to create a paper trail of all the previous urls this feed has lived at. This way, aggregators can easily deduplicate their feed lists.

• <podcast:alternateEnclosure url="[url of media asset]" type="[mime type]" length="[(int)]" bitrate="[(float)]" title="[(string)]" rel="[(string)]" />

  Channel (optional | single)

  Item (optional | multiple)

  This element is meant to provide alternate versions of an enclosure, such as low or high bitrate, or alternate formats or alternate uri schemes, like IPFS or live streaming. There may be multiple alternateEnclosure elements in an item, but there must be no more than one in a channel. The presence of this element at the channel level would be useful for adding a video/audio trailer or intro media that introduces the listener to the podcast. For instance, in a podcast of an audiobook, this could be the book's introduction or preface. The alternateEnclosure element always refers to an "alternate" media version. The standard RSS enclosure element is always the default media to be played.

  An <enclosure> tag must be present along with this tag within the item.

  • url (required) This is the url to the media asset.
  • type (required) Mime type of the media asset.
  • length (required) Length of the file in bytes.
  • bitrate (optional) Encoding bitrate of media asset.
  • title (required) Alternate assets need a title since main title will apply to primary asset.
  • rel (optional) Indicates what the purpose of this enclosure is. Like "lowbitrate" for a small file to use over cellular.

• <podcast:indexers> + <podcast:block>[domain, bot or service slug]</podcast:block>

  Channel (optional | single)

  The "indexers" element is meant as a container for one or more <podcast:block> elements which send a signal to podcast aggregators whether they are allowed to pull and parse this feed. If the aggregator is listed as blocked, it should take that as a signal by the feed owner to not index/aggregate this feed.

  Note: this element needs a lot more discussion and work. This is just a placeholder for discussion.

• <podcast:images srcset="[url to image] [pixelwidth(int)]w, [url to image] [pixelwidth(int)]w, [url to image] [pixelwidth(int)]w, [url to image] [pixelwidth(int)]w" />

  Channel or Item

  (optional | single)

  This points to a group of images, separated by commas - each with a pixel width declared after them. It is highly recommended that the images referenced be square (1:1 ratio), as this is the industry standard for podcast album art, and what podcast apps expect to work with. The srcset attribute is designed to work like the srcset attribute in the HTML5 specification. Suggested widths are 1500px, 600px, 300px and 150px. See the example feed in this repo for an example of how this looks in practice.

  All attributes are required.

• <podcast:contact type="[feedback or advertising or abuse]">[email address or url]</podcast:contact>

  Channel

  (optional | multiple)

  This element allows for listing different contact methods for the podcast owner. This could be for general feedback, advertising inquiries, abuse reports, etc. Only one element of each "type" is allowed.

  All attributes are required.

• <podcast:value type="[lightning]" method="[keysend]" suggested="[number of bitcoin(float)]">[one or more "valueRecipient" elements]</podcast:value>

  Channel

  (optional | single)

  This element defines the payment "model". One or more <podcast:valueRecipient> tags must be contained within this element to instruct where to send the payments within this defined model.

  • type (required) What type of system will be receiving the payments. Currently only "lightning" is supported.
  • method (required) The protocol to use to send the payments. Currently only "keysend" is supported.
  • suggested (required) The amount to send per minute of episode play time, defined in bitcoin (float, 0.00000005000 is 5sat/min).

• <podcast:valueRecipient name="[name of recipient(string)]" type="[node]" address="[public key of bitcoin/lightning node(string)]" split="[percentage(int)]" />

  Channel

  (required | multiple)

  • name (optional) A friendly name to identify the receipient.
  • type (required) The type of destination this is. Currently, only "node" is supported.
  • address (required) The address of the digital wallet or node that will receive payments.
  • split (required) Defines a percentage that this payment destination represents. Payments will be sent to each destination in the "value" block, dividing up by this percentage.

Verification for Importing and Transferring

If the "locked" element is present and set to "yes", podcasting hosts should not allow importing of this feed until the email listed in the element's owner="" attribute is contacted and subsequently changes the value of the element to "no".

IDs

Their can be multiple <podcast:id> elements to indicate a listing on multiple platforms, directories, hosts, apps and services. The "platform" attribute shall be a slug representing the platform, directory, host, app or service. The slugs will look like this:

• blubrry
• captivate
• podcastindex
• fireside
• transistor
• libsyn
• buzzsprout
• apple
• google
• spotify
• anchor
• overcast

More should be added by the community as needed. This is just a starter list. The full list is here.