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WIP Spec
This document describes aspects, technological and not, of the various systems used in media production and distribution as they relate to podcasting. In this document, the term "podcasting" refers to the publishing of audio content on the surface web using standard technologies via a document describing the content and associated metadata.
This document recognizes that it is common to refer to discrete pieces of content (e.g. episodes) or related groups of content (e.g. shows or series) as "podcasts". In order to avoid confusion or ambiguity, this document will not use the term podcast in that context; it refer only to a method of distribution.
You may not modify, merge, sublicense, and/or sell copies of the Specification.
THE SPECIFICATION IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SPECIFICATION OR THE USE OR OTHER DEALINGS IN THE SPECIFICATION.
Any sample code included in the Specification, unless otherwise specified, is licensed under the Apache License, Version 2.0.
Content of various types can make use of podcasting. That content may represent stories, programs, shows, classes, tutorials, news and weather reports, or many other formats. Podcasting is a form of distribution, in much the same way that DVD, FM radio, and cable television are forms of distribution.
At its most fundamental level, distribution of content through podcasting is accomplished by maintaining a well-formed text file (a "feed") on the world wide web which describes the content being distributed, and points to media assets for that content. In many cases a feed will contain information about a single show or series (which is to say, related content created by a single owner or entity), but not always.
Clients (hardware or software that are designed to utilize content available through podcasting) access the feeds, wherever they may be on the web, and make use of the metadata and media. Because feeds are available on the web, and the format of all feeds is mostly standardized, there are few limitations on who can build a client, or which podcasting content any given client has access to.
By definition, if a feed exists only behind a paywall or another means of keeping web content private (e.g. password protection), that feed is not being distributed through podcasting.
A feed used for podcasting describes fully (or provides access to resources that, as a whole, describe fully) the content being made available. The feed is a text file that implements a number of standards.
A feed MUST adhere to the RSS 2.0 Specification.
A feed MUST use UTF-8 character encoding.
A feed MUST have a media type of application/rss+xml.
A feed MUST be available via HTTPS.
Audio will follow the EBU R128 standards for loudness, with the following stipulations:
- Programme Loudness Level shall be normalised to a Target Level of -16.0 LUFS, not -23.0 LUFS
- When multiple programmes (as defined by EBU R128; including ads, promos, etc) are, in the case of podcasting distribution, contained within a single audio file, each programme shall be normalised independently
- A -3 dB attenuation of the target level MAY be employed when dealing with mono channel audio