ikiwiki's simple podcasting, while elegant and minimal, doesn't (as
mentioned in [[todo/blogging]]) produce full-featured feeds. In
fancy podcasts, episodes are accompanied by text content. The feeds
also have lots more metadata.

[[!toc]]

## Design

7. For each fancy podcast episode, write a blog post containing
   `\[[!meta enclosure="WikiLink/to/media.mp3"]]`. (Don't specify
   more than one enclosure -- but if you do, last one wins.)
7. When rendering to HTML (single-page or inlined), append a link
   to the media file.
7. When rendering to RSS/Atom, the text is the entry's content and
   the media file is its enclosure.
7. Don't break simple podcasts in pursuit of fancy podcasts.

## Implementation

[[!template id=gitbranch branch=schmonz/fancypodcast author="[[schmonz]]"]]
[[!tag patch]]

### Completed

* Cover the existing simple podcast behavior with tests.
* Add an `enclosure` field to [[plugins/meta]] that expands the
  given [[ikiwiki/WikiLink]] to an absolute URL (feed enclosures
  pretty much need to be, and the reference feeds I've looked at
  all do this).
* Write failing tests for the desired single-page and inlined
  HTML behavior, then make them pass by adding enclosure stanzas
  to `{,inline}page.tmpl`.
* Write failing tests for the desired RSS/Atom behavior, then make
  them pass via changes to `{atom,rss}item.tmpl` and [[plugins/inline]].
* Match feature-for-feature with
  [tru_podcast](http://www.rainskit.com/blog/542/tru_podcast-a-podcasting-plugin-for-textpattern)
  (what [[schmonz]] will be migrating from).
* Enrich [feed metadata](http://cyber.law.harvard.edu/rss/rss.html)
  by catching up `rsspage.tmpl` to `atompage.tmpl`.
* Verify that [[plugins/more]] plays well with fancy podcasts.
* Verify that the feeds validate.
* Subscribe to a fancy feed in some common podcatchers and verify
  display details against a reference podcast.

### Status

[[!table data="""
Feature            |iTunes RSS|iTunes Atom|Downcast RSS|Downcast Atom
Feed image         |{X}       |{X}        |{X}         |{X}
Feed title         |(./)      |(./)       |(./)        |(./)
Feed publisher     |{X}       |{X}        |{X}         |{X}
Feed "category"    |{X}       |{X}        |{X}         |{X}
Feed date          |(./)      |(./)       |(./)        |(./)
Feed description   |(./)      |(./)       |(./)        |{X}
Episode image      |{X}       |{X}        |{X}         |{X}
Episode title      |(./)      |(./)       |(./)        |(./)
Episode date       |(./)      |(./)       |(./)        |(./)
Episode duration   |{X}       |{X}        |{X}         |{X}
Episode author     |{X}       |{X}        |{X}         |{X}
Episode description|(./)      |(./)       |(./)        |{X}
Episode enclosure  |(./)      |(./)       |(./)        |(./)
"""]]

### Must-have (for [[schmonz]], anyway)

* Think carefully about...
    * UTF-8.
    * Whether [[tips/howto avoid flooding aggregators]] suffices for
      migrating a fancy podcast into ikiwiki.
* Verify that _all_ the tests pass (not just my new ones).

-----

## Future improvements

### iTunes fancy podcasting

* [iTunes-specific tags](https://www.apple.com/itunes/podcasts/specs.html)
  appear to be RSS-only
    * If they work in Atom, teach `inline` to optionally iTunesify RSS/Atom.
    * Else, add `itunes` as a third kind of feed (RSS plus more stuff).
* Notable tags for feeds:
    * `itunes:subtitle`
    * `itunes:author`
    * `itunes:summary` (same as `description`)
    * `itunes:owner` (includes `itunes:name` and `itunes:email`)
    * `itunes:image href=''`
    * `itunes:publisher`
    * `itunes:category text=''` (can contain subcategories)
    * `itunes:keywords`
* Notable tags for entries:
    * `itunes:duration`
        * [[!cpan Audio::TagLib]] might be fastest, if present and applicable
        * [ffprobe](http://ffmpeg.org/ffprobe.html) is reasonably fast
        * [mediainfo](http://mediainfo.sourceforge.net/) is way slower
        * Cache computed durations as pagestate

### Fancy podcast aggregating

* Write tests comparing a fancy podcast (HTML and feeds) against
  the same podcast aggregated and republished, then make them pass
  via changes to `aggregatepost.impl` and [[plugins/aggregate]].

### Other ideas

* Optionally specify the enclosure's:
    * MIME type, in case `File::MimeInfo` guesses wrong.
    * Duration, in case `ffprobe` guesses wrong.
* Optionally specify enclosures outside the wiki:
    * Some people don't want to store big unchanging files in the VCS.
    * Other people like [podcasting found media](http://huffduffer.com/about).
    * We'd have to download the file just to compute some metadata
      about it, and then somehow not frequently re-download it.
* Configurably generate additional subscription links (such as
  iTunes) alongside the RSS/Atom ones in [[plugins/inline]].
* Support Apple's "enhanced podcasts" (if they're still relevant).