adding support for audio uploads, transcoded to mp4 videos

app/models/media_attachment.rb

@@ -23,15 +23,31 @@ require 'mime/types'
 class MediaAttachment < ApplicationRecord
   self.inheritance_column = nil
 
-  enum type: [:image, :gifv, :video, :unknown]
+  enum type: [:image, :gifv, :video, :audio, :unknown]
 
   IMAGE_FILE_EXTENSIONS = ['.jpg', '.jpeg', '.png', '.gif'].freeze
   VIDEO_FILE_EXTENSIONS = ['.webm', '.mp4', '.m4v'].freeze
+  AUDIO_FILE_EXTENSIONS = ['.mp3', '.m4a', '.wav', '.ogg'].freeze
 
   IMAGE_MIME_TYPES = ['image/jpeg', 'image/png', 'image/gif'].freeze
   VIDEO_MIME_TYPES = ['video/webm', 'video/mp4'].freeze
+  AUDIO_MIME_TYPES = ['audio/mpeg', 'audio/mp4', 'audio/vnd.wav', 'audio/wav', 'audio/x-wav', 'audio/x-wave', 'audio/ogg',].freeze
 
   IMAGE_STYLES = { original: '1280x1280>', small: '400x400>' }.freeze
+  AUDIO_STYLES = {
+    original: {
+        format: 'mp4',
+        convert_options: {
+            output: {
+                filter_complex: '"[0:a]compand,showwaves=s=640x360:mode=line,format=yuv420p[v]"',
+                map: '"[v]" -map 0:a', 
+                threads: 2,
+                vcodec: 'libx264',
+                acodec: 'aac',
+            },
+        },
+    },
+  }.freeze
   VIDEO_STYLES = {
     small: {
       convert_options: {
@@ -54,7 +70,7 @@ class MediaAttachment < ApplicationRecord
 
   include Remotable
 
-  validates_attachment_content_type :file, content_type: IMAGE_MIME_TYPES + VIDEO_MIME_TYPES
+  validates_attachment_content_type :file, content_type: IMAGE_MIME_TYPES + VIDEO_MIME_TYPES + AUDIO_MIME_TYPES
   validates_attachment_size :file, less_than: 8.megabytes
 
   validates :account, presence: true
@@ -107,6 +123,8 @@ class MediaAttachment < ApplicationRecord
         }
       elsif IMAGE_MIME_TYPES.include? f.instance.file_content_type
         IMAGE_STYLES
+      elsif AUDIO_MIME_TYPES.include? f.instance.file_content_type
+        AUDIO_STYLES
       else
         VIDEO_STYLES
       end
@@ -117,6 +135,8 @@ class MediaAttachment < ApplicationRecord
         [:gif_transcoder]
       elsif VIDEO_MIME_TYPES.include? f.file_content_type
         [:video_transcoder]
+      elsif AUDIO_MIME_TYPES.include? f.file_content_type
+        [:audio_transcoder]
       else
         [:thumbnail]
       end
@@ -137,8 +157,8 @@ class MediaAttachment < ApplicationRecord
   end
 
   def set_type_and_extension
-    self.type = VIDEO_MIME_TYPES.include?(file_content_type) ? :video : :image
-    extension = appropriate_extension
+    self.type = VIDEO_MIME_TYPES.include?(file_content_type) ? :video : AUDIO_MIME_TYPES.include?(file_content_type) ? :audio : :image
+    extension = AUDIO_MIME_TYPES.include?(file_content_type) ? '.mp4' : appropriate_extension
     basename  = Paperclip::Interpolations.basename(file, :original)
     file.instance_write :file_name, [basename, extension].delete_if(&:blank?).join('.')
   end

app/serializers/initial_state_serializer.rb

@@ -52,6 +52,6 @@ class InitialStateSerializer < ActiveModel::Serializer
   end
 
   def media_attachments
-    { accept_content_types: MediaAttachment::IMAGE_FILE_EXTENSIONS + MediaAttachment::VIDEO_FILE_EXTENSIONS + MediaAttachment::IMAGE_MIME_TYPES + MediaAttachment::VIDEO_MIME_TYPES }
+    { accept_content_types: MediaAttachment::IMAGE_FILE_EXTENSIONS + MediaAttachment::VIDEO_FILE_EXTENSIONS + MediaAttachment::AUDIO_FILE_EXTENSIONS + MediaAttachment::IMAGE_MIME_TYPES + MediaAttachment::VIDEO_MIME_TYPES + MediaAttachment::AUDIO_MIME_TYPES }
   end
 end

config/application.rb

@@ -9,6 +9,7 @@ Bundler.require(*Rails.groups)
 require_relative '../app/lib/exceptions'
 require_relative '../lib/paperclip/gif_transcoder'
 require_relative '../lib/paperclip/video_transcoder'
+require_relative '../lib/paperclip/audio_transcoder'
 require_relative '../lib/mastodon/version'
 
 Dotenv::Railtie.load

lib/paperclip/audio_transcoder.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module Paperclip
+  class AudioTranscoder < Paperclip::Processor
+    def make
+       final_file = Paperclip::Transcoder.make(file, options, attachment)
+
+       attachment.instance.file_file_name    = 'media.mp4'
+       attachment.instance.file_content_type = 'video/mp4'
+       attachment.instance.type              = MediaAttachment.types[:video]
+
+       final_file
+    end
+  end
+end