Choose the best audio version of an entry

Both templates took element 0 of the entry's audio resources, so an
entry carrying more than one encoding used whichever filename sorted
first, with no way to express a preference. An entry with a careful
encoding and an mp3 beside it would commonly have offered the mp3.

Order the resources by how they sound instead. Public listening tests
put Opus ahead of the field at the bitrates spoken word uses, with
Vorbis and AAC close behind it and MP3 last; the lossless formats come
after the lossy ones rather than before, since a browser that can play
FLAC would otherwise fetch several times the bytes for no audible gain.
Formats the theme does not rank keep Hugo's own order at the end.

The capsule links the first of them, since a Gemini client cannot
choose between sources and a reader wants one file to fetch. The
website offers them all as the alternative sources that the audio
element exists to choose between, best first, so a browser plays the
best encoding it understands.

Hugo reports .opus, .oga and .ogg alike as audio/ogg, so the ordering
keys off the file extension rather than the media type.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

3 files changed, 37 insertions, 5 deletions

diff --git a/layouts/_partials/audio.html b/layouts/_partials/audio.html
new file mode 100644
index 0000000..a99e9b3
--- /dev/null
+++ b/layouts/_partials/audio.html
@@ -0,0 +1,32 @@
+{{/* Returns the page's audio resources, best sounding first, so that a
+     browser takes the best encoding it can play and the capsule links
+     the best single file. Public listening tests put Opus ahead of the
+     field at the bitrates spoken word uses, with Vorbis and AAC close
+     behind it and MP3 last. Lossless comes after the lossy codecs
+     rather than before, since a browser that can play FLAC would
+     otherwise fetch several times the bytes for no audible gain.
+
+     Hugo reports .opus, .oga and .ogg alike as audio/ogg, so the
+     extension is what tells the codecs apart. Formats not listed here
+     keep Hugo's own order at the end. Returns an empty slice when there
+     is no audio. */ -}}
+
+{{ $preferred := slice ".opus" ".ogg" ".oga" ".m4a" ".aac" ".mp3" ".flac" ".wav" -}}
+{{ $audio := where .Resources "MediaType.MainType" "audio" -}}
+{{ $ordered := slice -}}
+
+{{ range $extension := $preferred -}}
+  {{ range $audio -}}
+    {{ if eq (lower (path.Ext .Name)) $extension -}}
+      {{ $ordered = $ordered | append . -}}
+    {{ end -}}
+  {{ end -}}
+{{ end -}}
+
+{{ range $audio -}}
+  {{ if not (in $preferred (lower (path.Ext .Name))) -}}
+    {{ $ordered = $ordered | append . -}}
+  {{ end -}}
+{{ end -}}
+
+{{ return $ordered }}
diff --git a/layouts/single.gmi b/layouts/single.gmi
index 29df881..2cee33d 100644
--- a/layouts/single.gmi
+++ b/layouts/single.gmi
@@ -8,9 +8,9 @@
 {{ partial "pageinfo.gmi" . }}
 {{- end -}}
 
-{{ with index (where .Resources "MediaType.MainType" "audio") 0 }}
+{{ with partial "audio.html" . }}{{ with index . 0 }}
 => {{ .RelPermalink }} {{ emojify ":link:" }} {{ i18n "downloadAudio" $.Title }}
-{{- end }}
+{{- end }}{{ end }}
 
 {{ $content := chomp (.RawContent) -}}
 {{ $scratch := newScratch -}}
diff --git a/layouts/single.html b/layouts/single.html
index 9ea21f4..bb9b10e 100644
--- a/layouts/single.html
+++ b/layouts/single.html
@@ -11,10 +11,10 @@
     {{- if (.Page.Params.pageinfo | default true) }}
     <p class="entry__pageinfo">{{ partial "pageinfo.html" . }}</p>
     {{- end -}}
-    {{ with index (where .Resources "MediaType.MainType" "audio") 0 }}
+    {{ with partial "audio.html" . }}
     <audio class="entry__audio" controls preload="metadata" aria-label="{{ i18n "audioVersion" $.Title }}">
-      <source src="{{ .RelPermalink }}" type="{{ .MediaType }}">
-      {{ i18n "audioUnsupported" }}
+      {{ range . }}<source src="{{ .RelPermalink }}" type="{{ .MediaType }}">
+      {{ end }}{{ i18n "audioUnsupported" }}
     </audio>
     {{- end }}
   </div>