diff --git a/Gemfile.lock b/Gemfile.lock
index b8076b1b79..5d911dab41 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -59,7 +59,7 @@ GIT
 
 GIT
   remote: https://github.com/samvera-labs/active_encode.git
-  revision: adecfb1503c2a706661f716ff041ca7ad3c9c3d7
+  revision: 25c839f7fd88f1a42dbc56ba8ad3a0cfef1d4a6f
   branch: main
   specs:
     active_encode (1.2.3)
diff --git a/app/models/language_term.rb b/app/models/language_term.rb
index ae330096e4..e0ea959baf 100644
--- a/app/models/language_term.rb
+++ b/app/models/language_term.rb
@@ -15,20 +15,67 @@
 class LanguageTerm
   class LookupError < Exception; end
 
-  Store = File.join(Rails.root, 'config/iso639-2.yml')
+  class Iso6391 < LanguageTerm
+    STORE = File.join(Rails.root, 'config/iso639-1.yml')
+    VOCABULARY = 'http://id.loc.gov/vocabulary/iso639-1.tsv'
+
+    class << self
+      def convert_to_6392(term)
+        raise LookupError, "Incorrect number of characters. Term must be a string of 2 alphabetic characters." unless /[a-zA-Z]{2}/.match?(term)
+        lang_text = search(term).text
+        # ISO 639-1 can have multiple languages defined for a single code:
+        # 'es': "Spanish | Castilian".
+        # ISO 639-2 does not follow the same convention, so we iterate through
+        # any multi languages until we get a match from the ISO 639-2 standard.
+        lang_text = lang_text.split('|').map(&:strip) if lang_text.include?('|')
+        Array(lang_text).each do |text|
+          begin
+            @alpha3 = Iso6392.search(text)
+            break
+          rescue LookupError
+            next
+          end
+        end
+
+        raise LookupError, "Unknown language: `'#{value}" if @alpha3.nil?
+
+        return @alpha3
+      end
+
+      def map
+        @@map_alpha2 ||= self.load!
+      end
+    end
+  end
+
+  class Iso6392 < LanguageTerm
+    STORE = File.join(Rails.root, 'config/iso639-2.yml')
+    VOCABULARY = 'http://id.loc.gov/vocabulary/languages.tsv'
+
+    class << self
+      def map
+        @@map ||= self.load!
+      end
+    end
+  end
 
   class << self
-    def map
-      @@map ||= self.load!
+    def find(term)
+      case term.length
+      when 2
+        Iso6391.convert_to_6392(term)
+      else
+        Iso6392.search(term)
+      end
     end
+    alias_method :[], :find
 
-    def find(value)
+    def search(value)
       result = self.map[value.downcase]
       result = self.map.select{ |k,v| v[:text]==value }.values.first if result.nil?
       raise LookupError, "Unknown language: `#{value}'" if result.nil?
       self.new(result)
     end
-    alias_method :[], :find
 
     def autocomplete(query, _id = nil)
       map = query.present? ? self.map.select{ |k,v| /#{query}/i.match(v[:text]) if v } : self.map
@@ -36,8 +83,8 @@ def autocomplete(query, _id = nil)
     end
 
     def load!
-      if File.exist?(Store)
-        YAML.load(File.read(Store))
+      if File.exist?(store)
+        YAML.load(File.read(store))
       else
         harvest!
       end
@@ -45,11 +92,11 @@ def load!
 
     def harvest!
       language_map = {}
-      doc = RestClient.get('http://id.loc.gov/vocabulary/languages.tsv').split(/\n/).collect{ |l| l.split(/\t/) }
+      doc = RestClient.get(vocabulary).split(/\n/).collect{ |l| l.split(/\t/) }
       doc.shift
       doc.each { |entry| language_map[entry[1].to_s] = { code: entry[1].to_s, text: entry[2].to_s, uri: entry[0].to_s } }
       begin
-        File.open(Store,'w') { |f| f.write(YAML.dump(language_map)) }
+        File.open(store,'w') { |f| f.write(YAML.dump(language_map)) }
       rescue
         # Don't care if we can't cache it
       end
@@ -68,4 +115,20 @@ def code
   def text
     @term[:text]
   end
+
+  def store
+    self.class::STORE
+  end
+
+  def self.store
+    self::STORE
+  end
+
+  def vocabulary
+    self.class::VOCABULARY
+  end
+
+  def self.vocabulary
+    self::VOCABULARY
+  end
 end
diff --git a/app/models/media_object.rb b/app/models/media_object.rb
index c740147bd4..85f9ac9000 100644
--- a/app/models/media_object.rb
+++ b/app/models/media_object.rb
@@ -99,7 +99,7 @@ def validate_note_type
   end
 
   def validate_language
-    Array(language).each{|i|errors.add(:language, "Language not recognized (#{i[:code]})") unless LanguageTerm::map[i[:code]] }
+    Array(language).each{|i|errors.add(:language, "Language not recognized (#{i[:code]})") unless LanguageTerm::Iso6392.map[i[:code]] }
   end
 
   def validate_related_items
diff --git a/app/models/supplemental_file.rb b/app/models/supplemental_file.rb
index 25f90a17c2..dd74ace727 100644
--- a/app/models/supplemental_file.rb
+++ b/app/models/supplemental_file.rb
@@ -21,7 +21,7 @@ class SupplementalFile < ApplicationRecord
 
   # TODO: the empty tag should represent a generic supplemental file
   validates :tags, array_inclusion: ['transcript', 'caption', 'machine_generated', '', nil]
-  validates :language, inclusion: { in: LanguageTerm.map.keys }
+  validates :language, inclusion: { in: LanguageTerm::Iso6392.map.keys }
   validates :parent_id, presence: true
   validate  :validate_file_type, if: :caption?
 
diff --git a/app/models/watched_encode.rb b/app/models/watched_encode.rb
index b3a6b75f22..88434a5b80 100644
--- a/app/models/watched_encode.rb
+++ b/app/models/watched_encode.rb
@@ -36,6 +36,14 @@ class WatchedEncode < ActiveEncode::Base
       encode.output.collect! do |output|
         if output.format == "vtt"
           new_file = SupplementalFile.new(tags: ['caption'], parent_id: record.master_file_id)
+          new_file.label = output.label.presence
+          if output.language.present?
+            begin
+              new_file.language = LanguageTerm.find(output.language).code
+            rescue LanguageTerm::LookupError
+              new_file.language = nil
+            end
+          end
           new_file.attach_file(FileLocator.new(output.url).location, io: true)
           new_file.save
           output.url = if Settings.active_storage.bucket.present?
diff --git a/config/iso639-1.yml b/config/iso639-1.yml
new file mode 100644
index 0000000000..5a1e329321
--- /dev/null
+++ b/config/iso639-1.yml
@@ -0,0 +1,738 @@
+---
+aa:
+  :code: aa
+  :text: Afar
+  :uri: http://id.loc.gov/vocabulary/iso639-1/aa
+ab:
+  :code: ab
+  :text: Abkhazian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ab
+ae:
+  :code: ae
+  :text: Avestan
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ae
+af:
+  :code: af
+  :text: Afrikaans
+  :uri: http://id.loc.gov/vocabulary/iso639-1/af
+ak:
+  :code: ak
+  :text: Akan
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ak
+am:
+  :code: am
+  :text: Amharic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/am
+an:
+  :code: an
+  :text: Aragonese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/an
+ar:
+  :code: ar
+  :text: Arabic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ar
+as:
+  :code: as
+  :text: Assamese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/as
+av:
+  :code: av
+  :text: Avaric
+  :uri: http://id.loc.gov/vocabulary/iso639-1/av
+ay:
+  :code: ay
+  :text: Aymara
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ay
+az:
+  :code: az
+  :text: Azerbaijani
+  :uri: http://id.loc.gov/vocabulary/iso639-1/az
+ba:
+  :code: ba
+  :text: Bashkir
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ba
+be:
+  :code: be
+  :text: Belarusian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/be
+bg:
+  :code: bg
+  :text: Bulgarian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bg
+bh:
+  :code: bh
+  :text: Bihari languages
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bh
+bi:
+  :code: bi
+  :text: Bislama
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bi
+bm:
+  :code: bm
+  :text: Bambara
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bm
+bn:
+  :code: bn
+  :text: Bengali
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bn
+bo:
+  :code: bo
+  :text: Tibetan
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bo
+br:
+  :code: br
+  :text: Breton
+  :uri: http://id.loc.gov/vocabulary/iso639-1/br
+bs:
+  :code: bs
+  :text: Bosnian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/bs
+ca:
+  :code: ca
+  :text: Catalan |  Valencian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ca
+ce:
+  :code: ce
+  :text: Chechen
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ce
+ch:
+  :code: ch
+  :text: Chamorro
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ch
+co:
+  :code: co
+  :text: Corsican
+  :uri: http://id.loc.gov/vocabulary/iso639-1/co
+cr:
+  :code: cr
+  :text: Cree
+  :uri: http://id.loc.gov/vocabulary/iso639-1/cr
+cs:
+  :code: cs
+  :text: Czech
+  :uri: http://id.loc.gov/vocabulary/iso639-1/cs
+cu:
+  :code: cu
+  :text: Church Slavic |  Old Slavonic |  Church Slavonic |  Old Bulgarian |  Old
+    Church Slavonic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/cu
+cv:
+  :code: cv
+  :text: Chuvash
+  :uri: http://id.loc.gov/vocabulary/iso639-1/cv
+cy:
+  :code: cy
+  :text: Welsh
+  :uri: http://id.loc.gov/vocabulary/iso639-1/cy
+da:
+  :code: da
+  :text: Danish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/da
+de:
+  :code: de
+  :text: German
+  :uri: http://id.loc.gov/vocabulary/iso639-1/de
+dv:
+  :code: dv
+  :text: Divehi |  Dhivehi |  Maldivian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/dv
+dz:
+  :code: dz
+  :text: Dzongkha
+  :uri: http://id.loc.gov/vocabulary/iso639-1/dz
+ee:
+  :code: ee
+  :text: Ewe
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ee
+el:
+  :code: el
+  :text: Greek, Modern (1453-)
+  :uri: http://id.loc.gov/vocabulary/iso639-1/el
+en:
+  :code: en
+  :text: English
+  :uri: http://id.loc.gov/vocabulary/iso639-1/en
+eo:
+  :code: eo
+  :text: Esperanto
+  :uri: http://id.loc.gov/vocabulary/iso639-1/eo
+es:
+  :code: es
+  :text: Spanish |  Castilian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/es
+et:
+  :code: et
+  :text: Estonian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/et
+eu:
+  :code: eu
+  :text: Basque
+  :uri: http://id.loc.gov/vocabulary/iso639-1/eu
+fa:
+  :code: fa
+  :text: Persian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/fa
+ff:
+  :code: ff
+  :text: Fulah
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ff
+fi:
+  :code: fi
+  :text: Finnish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/fi
+fj:
+  :code: fj
+  :text: Fijian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/fj
+fo:
+  :code: fo
+  :text: Faroese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/fo
+fr:
+  :code: fr
+  :text: French
+  :uri: http://id.loc.gov/vocabulary/iso639-1/fr
+fy:
+  :code: fy
+  :text: Western Frisian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/fy
+ga:
+  :code: ga
+  :text: Irish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ga
+gd:
+  :code: gd
+  :text: Gaelic |  Scottish Gaelic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/gd
+gl:
+  :code: gl
+  :text: Galician
+  :uri: http://id.loc.gov/vocabulary/iso639-1/gl
+gn:
+  :code: gn
+  :text: Guarani
+  :uri: http://id.loc.gov/vocabulary/iso639-1/gn
+gu:
+  :code: gu
+  :text: Gujarati
+  :uri: http://id.loc.gov/vocabulary/iso639-1/gu
+gv:
+  :code: gv
+  :text: Manx
+  :uri: http://id.loc.gov/vocabulary/iso639-1/gv
+ha:
+  :code: ha
+  :text: Hausa
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ha
+he:
+  :code: he
+  :text: Hebrew
+  :uri: http://id.loc.gov/vocabulary/iso639-1/he
+hi:
+  :code: hi
+  :text: Hindi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/hi
+ho:
+  :code: ho
+  :text: Hiri Motu
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ho
+hr:
+  :code: hr
+  :text: Croatian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/hr
+ht:
+  :code: ht
+  :text: Haitian |  Haitian Creole
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ht
+hu:
+  :code: hu
+  :text: Hungarian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/hu
+hy:
+  :code: hy
+  :text: Armenian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/hy
+hz:
+  :code: hz
+  :text: Herero
+  :uri: http://id.loc.gov/vocabulary/iso639-1/hz
+ia:
+  :code: ia
+  :text: Interlingua (International Auxiliary Language Association)
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ia
+id:
+  :code: id
+  :text: Indonesian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/id
+ie:
+  :code: ie
+  :text: Interlingue |  Occidental
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ie
+ig:
+  :code: ig
+  :text: Igbo
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ig
+ii:
+  :code: ii
+  :text: Sichuan Yi |  Nuosu
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ii
+ik:
+  :code: ik
+  :text: Inupiaq
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ik
+io:
+  :code: io
+  :text: Ido
+  :uri: http://id.loc.gov/vocabulary/iso639-1/io
+is:
+  :code: is
+  :text: Icelandic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/is
+it:
+  :code: it
+  :text: Italian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/it
+iu:
+  :code: iu
+  :text: Inuktitut
+  :uri: http://id.loc.gov/vocabulary/iso639-1/iu
+ja:
+  :code: ja
+  :text: Japanese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ja
+jv:
+  :code: jv
+  :text: Javanese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/jv
+ka:
+  :code: ka
+  :text: Georgian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ka
+kg:
+  :code: kg
+  :text: Kongo
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kg
+ki:
+  :code: ki
+  :text: Kikuyu |  Gikuyu
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ki
+kj:
+  :code: kj
+  :text: Kuanyama |  Kwanyama
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kj
+kk:
+  :code: kk
+  :text: Kazakh
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kk
+kl:
+  :code: kl
+  :text: Kalaallisut |  Greenlandic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kl
+km:
+  :code: km
+  :text: Central Khmer
+  :uri: http://id.loc.gov/vocabulary/iso639-1/km
+kn:
+  :code: kn
+  :text: Kannada
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kn
+ko:
+  :code: ko
+  :text: Korean
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ko
+kr:
+  :code: kr
+  :text: Kanuri
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kr
+ks:
+  :code: ks
+  :text: Kashmiri
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ks
+ku:
+  :code: ku
+  :text: Kurdish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ku
+kv:
+  :code: kv
+  :text: Komi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kv
+kw:
+  :code: kw
+  :text: Cornish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/kw
+ky:
+  :code: ky
+  :text: Kirghiz |  Kyrgyz
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ky
+la:
+  :code: la
+  :text: Latin
+  :uri: http://id.loc.gov/vocabulary/iso639-1/la
+lb:
+  :code: lb
+  :text: Luxembourgish |  Letzeburgesch
+  :uri: http://id.loc.gov/vocabulary/iso639-1/lb
+lg:
+  :code: lg
+  :text: Ganda
+  :uri: http://id.loc.gov/vocabulary/iso639-1/lg
+li:
+  :code: li
+  :text: Limburgan |  Limburger |  Limburgish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/li
+ln:
+  :code: ln
+  :text: Lingala
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ln
+lo:
+  :code: lo
+  :text: Lao
+  :uri: http://id.loc.gov/vocabulary/iso639-1/lo
+lt:
+  :code: lt
+  :text: Lithuanian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/lt
+lu:
+  :code: lu
+  :text: Luba-Katanga
+  :uri: http://id.loc.gov/vocabulary/iso639-1/lu
+lv:
+  :code: lv
+  :text: Latvian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/lv
+mg:
+  :code: mg
+  :text: Malagasy
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mg
+mh:
+  :code: mh
+  :text: Marshallese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mh
+mi:
+  :code: mi
+  :text: Maori
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mi
+mk:
+  :code: mk
+  :text: Macedonian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mk
+ml:
+  :code: ml
+  :text: Malayalam
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ml
+mn:
+  :code: mn
+  :text: Mongolian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mn
+mr:
+  :code: mr
+  :text: Marathi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mr
+ms:
+  :code: ms
+  :text: Malay
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ms
+mt:
+  :code: mt
+  :text: Maltese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/mt
+my:
+  :code: my
+  :text: Burmese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/my
+na:
+  :code: na
+  :text: Nauru
+  :uri: http://id.loc.gov/vocabulary/iso639-1/na
+nb:
+  :code: nb
+  :text: Bokmål, Norwegian |  Norwegian Bokmål
+  :uri: http://id.loc.gov/vocabulary/iso639-1/nb
+nd:
+  :code: nd
+  :text: Ndebele, North |  North Ndebele
+  :uri: http://id.loc.gov/vocabulary/iso639-1/nd
+ne:
+  :code: ne
+  :text: Nepali
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ne
+ng:
+  :code: ng
+  :text: Ndonga
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ng
+nl:
+  :code: nl
+  :text: Dutch |  Flemish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/nl
+nn:
+  :code: nn
+  :text: Norwegian Nynorsk |  Nynorsk, Norwegian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/nn
+'no':
+  :code: 'no'
+  :text: Norwegian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/no
+nr:
+  :code: nr
+  :text: Ndebele, South |  South Ndebele
+  :uri: http://id.loc.gov/vocabulary/iso639-1/nr
+nv:
+  :code: nv
+  :text: Navajo |  Navaho
+  :uri: http://id.loc.gov/vocabulary/iso639-1/nv
+ny:
+  :code: ny
+  :text: Chichewa |  Chewa |  Nyanja
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ny
+oc:
+  :code: oc
+  :text: Occitan (post 1500)
+  :uri: http://id.loc.gov/vocabulary/iso639-1/oc
+oj:
+  :code: oj
+  :text: Ojibwa
+  :uri: http://id.loc.gov/vocabulary/iso639-1/oj
+om:
+  :code: om
+  :text: Oromo
+  :uri: http://id.loc.gov/vocabulary/iso639-1/om
+or:
+  :code: or
+  :text: Oriya
+  :uri: http://id.loc.gov/vocabulary/iso639-1/or
+os:
+  :code: os
+  :text: Ossetian |  Ossetic
+  :uri: http://id.loc.gov/vocabulary/iso639-1/os
+pa:
+  :code: pa
+  :text: Panjabi |  Punjabi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/pa
+pi:
+  :code: pi
+  :text: Pali
+  :uri: http://id.loc.gov/vocabulary/iso639-1/pi
+pl:
+  :code: pl
+  :text: Polish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/pl
+ps:
+  :code: ps
+  :text: Pushto |  Pashto
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ps
+pt:
+  :code: pt
+  :text: Portuguese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/pt
+qu:
+  :code: qu
+  :text: Quechua
+  :uri: http://id.loc.gov/vocabulary/iso639-1/qu
+rm:
+  :code: rm
+  :text: Romansh
+  :uri: http://id.loc.gov/vocabulary/iso639-1/rm
+rn:
+  :code: rn
+  :text: Rundi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/rn
+ro:
+  :code: ro
+  :text: Romanian |  Moldavian |  Moldovan
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ro
+ru:
+  :code: ru
+  :text: Russian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ru
+rw:
+  :code: rw
+  :text: Kinyarwanda
+  :uri: http://id.loc.gov/vocabulary/iso639-1/rw
+sa:
+  :code: sa
+  :text: Sanskrit
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sa
+sc:
+  :code: sc
+  :text: Sardinian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sc
+sd:
+  :code: sd
+  :text: Sindhi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sd
+se:
+  :code: se
+  :text: Northern Sami
+  :uri: http://id.loc.gov/vocabulary/iso639-1/se
+sg:
+  :code: sg
+  :text: Sango
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sg
+si:
+  :code: si
+  :text: Sinhala |  Sinhalese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/si
+sk:
+  :code: sk
+  :text: Slovak
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sk
+sl:
+  :code: sl
+  :text: Slovenian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sl
+sm:
+  :code: sm
+  :text: Samoan
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sm
+sn:
+  :code: sn
+  :text: Shona
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sn
+so:
+  :code: so
+  :text: Somali
+  :uri: http://id.loc.gov/vocabulary/iso639-1/so
+sq:
+  :code: sq
+  :text: Albanian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sq
+sr:
+  :code: sr
+  :text: Serbian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sr
+ss:
+  :code: ss
+  :text: Swati
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ss
+st:
+  :code: st
+  :text: Sotho, Southern
+  :uri: http://id.loc.gov/vocabulary/iso639-1/st
+su:
+  :code: su
+  :text: Sundanese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/su
+sv:
+  :code: sv
+  :text: Swedish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sv
+sw:
+  :code: sw
+  :text: Swahili
+  :uri: http://id.loc.gov/vocabulary/iso639-1/sw
+ta:
+  :code: ta
+  :text: Tamil
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ta
+te:
+  :code: te
+  :text: Telugu
+  :uri: http://id.loc.gov/vocabulary/iso639-1/te
+tg:
+  :code: tg
+  :text: Tajik
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tg
+th:
+  :code: th
+  :text: Thai
+  :uri: http://id.loc.gov/vocabulary/iso639-1/th
+ti:
+  :code: ti
+  :text: Tigrinya
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ti
+tk:
+  :code: tk
+  :text: Turkmen
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tk
+tl:
+  :code: tl
+  :text: Tagalog
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tl
+tn:
+  :code: tn
+  :text: Tswana
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tn
+to:
+  :code: to
+  :text: Tonga (Tonga Islands)
+  :uri: http://id.loc.gov/vocabulary/iso639-1/to
+tr:
+  :code: tr
+  :text: Turkish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tr
+ts:
+  :code: ts
+  :text: Tsonga
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ts
+tt:
+  :code: tt
+  :text: Tatar
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tt
+tw:
+  :code: tw
+  :text: Twi
+  :uri: http://id.loc.gov/vocabulary/iso639-1/tw
+ty:
+  :code: ty
+  :text: Tahitian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ty
+ug:
+  :code: ug
+  :text: Uighur |  Uyghur
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ug
+uk:
+  :code: uk
+  :text: Ukrainian
+  :uri: http://id.loc.gov/vocabulary/iso639-1/uk
+ur:
+  :code: ur
+  :text: Urdu
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ur
+uz:
+  :code: uz
+  :text: Uzbek
+  :uri: http://id.loc.gov/vocabulary/iso639-1/uz
+ve:
+  :code: ve
+  :text: Venda
+  :uri: http://id.loc.gov/vocabulary/iso639-1/ve
+vi:
+  :code: vi
+  :text: Vietnamese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/vi
+vo:
+  :code: vo
+  :text: Volapük
+  :uri: http://id.loc.gov/vocabulary/iso639-1/vo
+wa:
+  :code: wa
+  :text: Walloon
+  :uri: http://id.loc.gov/vocabulary/iso639-1/wa
+wo:
+  :code: wo
+  :text: Wolof
+  :uri: http://id.loc.gov/vocabulary/iso639-1/wo
+xh:
+  :code: xh
+  :text: Xhosa
+  :uri: http://id.loc.gov/vocabulary/iso639-1/xh
+yi:
+  :code: yi
+  :text: Yiddish
+  :uri: http://id.loc.gov/vocabulary/iso639-1/yi
+yo:
+  :code: yo
+  :text: Yoruba
+  :uri: http://id.loc.gov/vocabulary/iso639-1/yo
+za:
+  :code: za
+  :text: Zhuang |  Chuang
+  :uri: http://id.loc.gov/vocabulary/iso639-1/za
+zh:
+  :code: zh
+  :text: Chinese
+  :uri: http://id.loc.gov/vocabulary/iso639-1/zh
+zu:
+  :code: zu
+  :text: Zulu
+  :uri: http://id.loc.gov/vocabulary/iso639-1/zu
diff --git a/spec/factories/encode.rb b/spec/factories/encode.rb
index 507bdcb2fb..93789725ee 100644
--- a/spec/factories/encode.rb
+++ b/spec/factories/encode.rb
@@ -85,5 +85,7 @@
     id { "gid://avalon/SupplementalFile/1" }
     url { "file://#{Rails.root.join('spec', 'fixtures', 'caption.vtt')}"}
     format { "vtt" }
+    label { "Test Caption" }
+    language { "en" }
   end
 end
diff --git a/spec/models/language_term_spec.rb b/spec/models/language_term_spec.rb
new file mode 100644
index 0000000000..1924753ea9
--- /dev/null
+++ b/spec/models/language_term_spec.rb
@@ -0,0 +1,55 @@
+# Copyright 2011-2024, The Trustees of Indiana University and Northwestern
+#   University.  Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+# 
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software distributed
+#   under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+#   CONDITIONS OF ANY KIND, either express or implied. See the License for the
+#   specific language governing permissions and limitations under the License.
+# ---  END LICENSE_HEADER BLOCK  ---
+
+require 'rails_helper'
+
+describe LanguageTerm, type: :model do
+  describe "::Iso6391" do
+    describe ".convert_to_6392" do
+      it "takes an alpha2 code and returns the matching entry from the 639-2 vocab" do
+        expect(LanguageTerm::Iso6391.convert_to_6392('en').code).to eq 'eng'
+        # 'es' returns 'Spanish | Castilian', matches on 'Spanish'
+        expect(LanguageTerm::Iso6391.convert_to_6392('es').code).to eq 'spa'
+        # 'gd' returns 'Gaelic | Scottish Gaelic', matches on 'Scottish Gaelic'
+        expect(LanguageTerm::Iso6391.convert_to_6392('gd').code).to eq 'gla'
+      end
+
+      it "returns a lookup error if there is not a match" do
+        expect { LanguageTerm::Iso6391.convert_to_6392("ac") }.to raise_error(LanguageTerm::LookupError)
+      end
+
+      it "returns a lookup error if input does not equal 2 alphabetic characters" do
+        expect { LanguageTerm::Iso6391.convert_to_6392("a") }.to raise_error(LanguageTerm::LookupError)
+        expect { LanguageTerm::Iso6391.convert_to_6392("zebra") }.to raise_error(LanguageTerm::LookupError)
+        expect { LanguageTerm::Iso6391.convert_to_6392("35") }.to raise_error(LanguageTerm::LookupError)
+        expect { LanguageTerm::Iso6391.convert_to_6392("a.") }.to raise_error(LanguageTerm::LookupError)
+      end
+    end
+  end
+
+  context ".find" do
+    it "returns correct entry for plain text search" do
+      expect(described_class.find("Scottish Gaelic").instance_variable_get(:@term)).to eq({ :code=>"gla", :text=>"Scottish Gaelic", :uri=>"http://id.loc.gov/vocabulary/languages/gla" })
+    end
+
+    it "returns correct entry for code search" do
+      expect(described_class.find("spa").instance_variable_get(:@term)).to eq( { :code=>"spa", :text=>"Spanish", :uri=>"http://id.loc.gov/vocabulary/languages/spa" } )
+      expect(described_class.find("es").instance_variable_get(:@term)).to eq( { :code=>"spa", :text=>"Spanish", :uri=>"http://id.loc.gov/vocabulary/languages/spa" })
+    end
+
+    it "raises LookupError for terms not in the vocabulary" do
+      expect { described_class.find("zebra") }.to raise_error(LanguageTerm::LookupError)
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/models/watched_encode_spec.rb b/spec/models/watched_encode_spec.rb
index 77fa9e8d8a..72b380f2e3 100644
--- a/spec/models/watched_encode_spec.rb
+++ b/spec/models/watched_encode_spec.rb
@@ -104,13 +104,13 @@
 
       context 'with embedded captions' do
         let(:caption_file) { 'captions.vtt' }
+        let(:sup_file) { double(url: 'file://supplemental_files' + Rails.root.join('spec', 'fixtures', caption_file).to_s, format: "vtt", label: "Test Caption", language: nil) }
         let(:completed_encode) do
           running_encode.clone.tap do |e| 
             e.state = :completed
             output = double(url: 'file://' + Rails.root.join('spec', 'fixtures', fixture_file).to_s)
             allow(output).to receive(:url=)
             allow(output).to receive(:format)
-            sup_file = double(url: 'file://supplemental_files' + Rails.root.join('spec', 'fixtures', caption_file).to_s, format: "vtt")
             allow(sup_file).to receive(:url=)
             allow(sup_file).to receive(:id=)
             e.output = [output, sup_file]
@@ -126,6 +126,7 @@
           supplemental_file = SupplementalFile.last
           expect(supplemental_file.file).to be_attached
           expect(supplemental_file.file.byte_size).to be_positive
+          expect(supplemental_file.label).to eq "Test Caption"
           expect(master_file).to have_received(:update_progress_on_success!)
         end
 
@@ -135,6 +136,29 @@
           expect(encode_record.title).to eq fixture_file
           expect(encode_record.display_title).to eq fixture_file
         end
+
+        context "language processing" do
+          it "accepts two letter codes" do
+            allow(sup_file).to receive(:language).and_return("es")
+            encode.create!
+            supplemental_file = SupplementalFile.last
+            expect(supplemental_file.language).to eq "spa"
+          end
+
+          it "accepts three letter codes" do
+            allow(sup_file).to receive(:language).and_return("fre")
+            encode.create!
+            supplemental_file = SupplementalFile.last
+            expect(supplemental_file.language).to eq "fre"
+          end
+
+          it "defaults to English when there is an issue with the language code" do
+            allow(sup_file).to receive(:language).and_return("error")
+            encode.create!
+            supplemental_file = SupplementalFile.last
+            expect(supplemental_file.language).to eq "eng"
+          end
+        end 
       end
 
       after do