fix: show readable audio quality labels

Convert audio stream bitrates from bits per second to kilobit labels in listen mode so the quality selector shows values like 128k instead of 128000k.

Closes iv-org/invidious#2513

spec/invidious/helpers_spec.cr

@@ -31,6 +31,13 @@ Spectator.describe "Helper" do
     end
   end
 
+  describe "#format_audio_quality_label" do
+    it "formats audio bitrates as readable kilobit labels" do
+      expect(Helpers.format_audio_quality_label(128000)).to eq("128k")
+      expect(Helpers.format_audio_quality_label(50000)).to eq("50k")
+    end
+  end
+
   describe "#sign_token" do
     it "correctly signs a given hash" do
       token = {

src/invidious/helpers/helpers.cr

@@ -40,6 +40,10 @@ module Helpers
     return description
   end
 
+  def format_audio_quality_label(bitrate : Int) : String
+    "#{(bitrate / 1000).round.to_i}k"
+  end
+
   def cache_annotation(id, annotations)
     if !CONFIG.cache_annotations
       return

src/invidious/views/components/player.ecr

@@ -28,12 +28,13 @@
                 src_url = invidious_companion.public_url.to_s + src_url +
                             "&check=#{invidious_companion_check_id}" if (invidious_companion)
 
-                bitrate = fmt["bitrate"]
+                bitrate = fmt["bitrate"].as_i
+                quality_label = Helpers.format_audio_quality_label(bitrate)
                 mimetype = HTML.escape(fmt["mimeType"].as_s)
 
                 selected = (i == best_m4a_stream_index)
             %>
-                <source src="<%= src_url %>" type='<%= mimetype %>' label="<%= bitrate %>k" selected="<%= selected %>">
+                <source src="<%= src_url %>" type='<%= mimetype %>' label="<%= quality_label %>" selected="<%= selected %>">
                 <% if !params.local && !CONFIG.disabled?("local") %>
                 <source src="<%= src_url %>&local=true" type='<%= mimetype %>' hidequalityoption="true">
                 <% end %>