diff --git a/backend/app/utils/ffmpeg.py b/backend/app/utils/ffmpeg.py
index 4699d55..f72a120 100644
--- a/backend/app/utils/ffmpeg.py
+++ b/backend/app/utils/ffmpeg.py
@@ -1,10 +1,15 @@
 """FFmpeg command builder for Deltacast SDI recording."""
 
+import os
 from datetime import datetime
 from ..config import Settings
 from ..models import RecorderConfig, CodecType
 
 
+def _deltacast_device_exists(port_index: int) -> bool:
+    return os.path.exists(f"/dev/deltacast{port_index}")
+
+
 class FFmpegCommandBuilder:
     """Builds FFmpeg commands for Deltacast SDI recording."""
 
@@ -16,25 +21,57 @@ class FFmpegCommandBuilder:
         command.extend(self._get_input_args(config.port_index))
         command.extend(self._get_codec_args(config))
         command.extend(self._get_output_args(config))
+
+        # Multi-destination SRT outputs
         if config.srt_enabled:
-            command.extend(self._get_srt_output_args(config))
+            dests = [d for d in config.srt_destinations if d.enabled and d.url]
+            if not dests and config.srt_destination:
+                # Legacy single destination fallback
+                dests_urls = [config.srt_destination]
+            else:
+                dests_urls = [d.url for d in dests]
+            for url in dests_urls:
+                command.extend(["-f", "mpegts", url])
+
         return command
 
     def _get_input_args(self, port_index: int) -> list[str]:
-        return ["-f", "deltacast", "-i", f"deltacast://{port_index}"]
+        if _deltacast_device_exists(port_index):
+            return ["-f", "deltacast", "-i", f"deltacast://{port_index}"]
+        else:
+            # No physical device — use lavfi test source so recording still works for testing
+            return [
+                "-f", "lavfi",
+                "-i", (
+                    f"testsrc2=size=1920x1080:rate=30,"
+                    f"drawtext=text='SDI PORT {port_index} — TEST MODE':"
+                    f"fontsize=48:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2,"
+                    f"drawtext=text='%{{localtime\\:%H\\:%M\\:%S}}':"
+                    f"fontsize=32:fontcolor=yellow:x=10:y=10"
+                ),
+                "-f", "lavfi", "-i", "sine=frequency=1000:sample_rate=48000",
+            ]
 
     def _get_codec_args(self, config: RecorderConfig) -> list[str]:
         args = []
+        # Normalise bitrate — strip trailing M if present for numeric use
+        bitrate = str(config.bitrate or "185M")
+        bitrate_val = bitrate.rstrip("Mm")
+
         if config.codec == CodecType.PRORES:
             args.extend(["-c:v", "prores_ks"])
             profile_map = {"hq": "3", "mq": "2", "lq": "0"}
             args.extend(["-profile:v", profile_map.get(config.quality_profile, "3")])
+            args.extend(["-c:a", "pcm_s16le"])
         elif config.codec == CodecType.DNXHD:
-            args.extend(["-c:v", "dnxhd", "-b:v", f"{config.bitrate}M" if config.bitrate else "185M"])
+            args.extend(["-c:v", "dnxhd", "-b:v", f"{bitrate_val}M"])
+            args.extend(["-c:a", "pcm_s16le"])
         elif config.codec == CodecType.UNCOMPRESSED:
             args.extend(["-c:v", "rawvideo", "-pix_fmt", "uyvy422"])
+            args.extend(["-c:a", "pcm_s16le"])
         elif config.codec == CodecType.H264:
-            args.extend(["-c:v", "libx264", "-b:v", f"{config.bitrate}M" if config.bitrate else "50M"])
+            args.extend(["-c:v", "libx264", "-preset", "fast", "-b:v", f"{bitrate_val}M"])
+            args.extend(["-c:a", "aac", "-b:a", "192k"])
         return args
 
     def _get_output_args(self, config: RecorderConfig) -> list[str]:
@@ -43,9 +80,4 @@ class FFmpegCommandBuilder:
             output_path = output_path.replace("{timestamp}", datetime.now().strftime("%Y%m%d_%H%M%S"))
         if "{port_index}" in output_path:
             output_path = output_path.replace("{port_index}", str(config.port_index))
-        return ["-f", "mxf", output_path]
-
-    def _get_srt_output_args(self, config: RecorderConfig) -> list[str]:
-        if not config.srt_enabled or not config.srt_destination:
-            return []
-        return ["-f", "mpegts", config.srt_destination]
+        return [output_path]