Fix YouTube in attesa: audio AAC di riserva, retry attivazione broadcast

Il relay verso YouTube ora gestisce _air senza traccia audio, ritenta
activate_broadcast finché l'ingest è active e riduce la finestra
scheduledStartTime a ~20s.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/streams/youtube_relay.rb

@@ -21,7 +21,7 @@ module Streams
 
         # YouTube richiede FLV H.264/AAC stabili; -c copy lascia spesso streamStatus=inactive.
         pid = Process.spawn(
-          *youtube_ffmpeg_args(intake, output, log_path),
+          *youtube_ffmpeg_args(intake, output, log_path, with_audio: intake_has_audio?(intake)),
           pgroup: true
         )
         Process.detach(pid)
@@ -68,13 +68,28 @@ module Streams
 
       private
 
-      def youtube_ffmpeg_args(intake, output, log_path)
-        [
+      def youtube_ffmpeg_args(intake, output, log_path, with_audio:)
+        base = [
           "ffmpeg", "-nostdin", "-hide_banner", "-loglevel", "warning",
           "-fflags", "+genpts+discardcorrupt", "-use_wallclock_as_timestamps", "1",
           "-rw_timeout", "15000000",
-          "-i", intake,
-          "-map", "0:v:0", "-map", "0:a:0",
+          "-i", intake
+        ]
+        encode = youtube_encode_flags(output, log_path)
+
+        if with_audio
+          base + ["-map", "0:v:0", "-map", "0:a:0"] + encode
+        else
+          # _air senza audio (overlay 0:a?): YouTube richiede comunque AAC.
+          base + [
+            "-f", "lavfi", "-i", "anullsrc=channel_layout=mono:sample_rate=48000",
+            "-map", "0:v:0", "-map", "1:a:0"
+          ] + encode
+        end
+      end
+
+      def youtube_encode_flags(output, log_path)
+        [
           "-c:v", "libx264", "-preset", "veryfast", "-tune", "zerolatency",
           "-pix_fmt", "yuv420p", "-r", "30", "-g", "30", "-keyint_min", "30", "-sc_threshold", "0",
           "-b:v", "4000k", "-maxrate", "4000k", "-bufsize", "8000k",
@@ -84,10 +99,21 @@ module Streams
         ]
       end
 
+      def intake_has_audio?(url)
+        require "open3"
+        stdout, _stderr, status = Open3.capture3(
+          "ffprobe", "-v", "error", "-rw_timeout", "5000000",
+          "-select_streams", "a", "-show_entries", "stream=index", "-of", "csv=p=0", url
+        )
+        status.success? && stdout.strip.present?
+      rescue StandardError
+        false
+      end
+
       def schedule_youtube_activate(session)
         return if session.youtube_broadcast_id.blank?
 
-        YoutubeBroadcastActivateJob.set(wait: 8.seconds).perform_later(session.id)
+        YoutubeBroadcastActivateJob.schedule_with_retries(session.id)
       end
 
       def mediamtx_intake_url(session)

backend/app/services/youtube/broadcast_service.rb

@@ -51,31 +51,38 @@ module Youtube
     end
 
     # Porta in onda appena c’è ingest su YouTube (non attendere scheduledStartTime).
+    # @return [Symbol] :live, :waiting_ingest, :transitioned, :skipped
     def activate_broadcast!(broadcast_id)
-      return if broadcast_id.blank?
-      return if @credential.blank? || missing_oauth_config?
+      return :skipped if broadcast_id.blank?
+      return :skipped if @credential.blank? || missing_oauth_config?
 
       client = authorized_client
       item = client.list_live_broadcasts("status,contentDetails", id: broadcast_id).items&.first
-      return unless item
+      return :skipped unless item
 
       status = item.status.life_cycle_status.to_s
-      return if status == "live"
+      return :live if status == "live"
 
       stream_id = item.content_details&.bound_stream_id
       if stream_id.present?
         stream = client.list_live_streams("status", id: stream_id).items&.first
-        return if stream&.status&.stream_status != "active"
+        stream_status = stream&.status&.stream_status.to_s
+        return :waiting_ingest unless stream_status == "active"
       end
 
       if %w[ready created].include?(status)
         client.transition_live_broadcast("testing", broadcast_id, "id,status")
         status = "testing"
       end
-      client.transition_live_broadcast("live", broadcast_id, "id,status") if status == "testing"
+      if status == "testing"
+        client.transition_live_broadcast("live", broadcast_id, "id,status")
+        return :transitioned
+      end
+
+      :skipped
     rescue Google::Apis::Error => e
       Rails.logger.warn("[Youtube::BroadcastService] activate #{broadcast_id}: #{e.message}")
-      nil
+      :skipped
     end
 
     def complete_broadcast!(broadcast_id)
@@ -131,7 +138,7 @@ module Youtube
     # YouTube richiede scheduledStartTime nel futuro; per «vai subito» usiamo ~1 min (auto_start al RTMP).
     def normalize_scheduled_start_time(scheduled_at)
       now = Time.current.utc
-      minimum = now + 90.seconds
+      minimum = now + 20.seconds
       maximum = now + 7.days
 
       candidate =