Safely fallback if FFmpeg does not support the arnnoise audio filter

app/upscaler.py

@@ -7,6 +7,19 @@ import time
 import threading
 from typing import Dict, Any, Callable
 
+_ffmpeg_filters_cache = {}
+def has_ffmpeg_filter(filter_name: str) -> bool:
+    global _ffmpeg_filters_cache
+    if filter_name in _ffmpeg_filters_cache:
+        return _ffmpeg_filters_cache[filter_name]
+    try:
+        p = subprocess.Popen(["ffmpeg", "-filters"], stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+        stdout, _ = p.communicate(timeout=5)
+        _ffmpeg_filters_cache[filter_name] = filter_name in stdout
+    except Exception:
+        _ffmpeg_filters_cache[filter_name] = False
+    return _ffmpeg_filters_cache[filter_name]
+
 # Paths config
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 BIN_PATH = os.path.join(BASE_DIR, "realesrgan-bin", "realesrgan-ncnn-vulkan")
@@ -623,13 +636,15 @@ def run_upscale_pipeline(job: UpscaleJob, on_progress_update: Callable[[str, Dic
         
         if job.preserve_audio:
             assemble_cmd.extend(["-map", "1:a:0?"])
-            if getattr(job, "ai_audio_denoise", False):
+            if getattr(job, "ai_audio_denoise", False) and has_ffmpeg_filter("arnnoise"):
                 acodec_denoise = "libvorbis" if transcode_fmt == "webm" else "aac"
                 assemble_cmd.extend([
                     "-af", "arnnoise",
                     "-c:a", acodec_denoise
                 ])
             else:
+                if getattr(job, "ai_audio_denoise", False):
+                    print(f"Warning: ai_audio_denoise was requested but 'arnnoise' filter is not available in ffmpeg. Copying audio without denoise.")
                 assemble_cmd.extend(["-c:a", acodec])
             
         if getattr(job, "preserve_subtitles", True):