Fix relay YouTube bloccato: rimuovi ffprobe su RTMP live

ffprobe su rtmp://mediamtx si bloccava in Sidekiq e impediva
l'avvio del relay verso YouTube (pagina sempre in attesa).

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, with_audio: intake_has_audio?(intake)),
+          *youtube_ffmpeg_args(intake, output, log_path),
           pgroup: true
         )
         Process.detach(pid)
@@ -68,28 +68,16 @@ module Streams
 
       private
 
-      def youtube_ffmpeg_args(intake, output, log_path, with_audio:)
-        base = [
+      # Non usare ffprobe su RTMP live: si blocca e impedisce l'avvio del relay (Sidekiq in hang).
+      # Audio: traccia AAC da anullsrc (YouTube la richiede); il mic del telefono resta su _air/HLS.
+      def youtube_ffmpeg_args(intake, output, log_path)
+        [
           "ffmpeg", "-nostdin", "-hide_banner", "-loglevel", "warning",
           "-fflags", "+genpts+discardcorrupt", "-use_wallclock_as_timestamps", "1",
           "-rw_timeout", "15000000",
-          "-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 + [
+          "-i", intake,
           "-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)
-        [
+          "-map", "0:v:0", "-map", "1:a:0",
           "-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",
@@ -99,17 +87,6 @@ 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?