Update app.py

app.py

@@ -203,7 +203,6 @@ def get_media_duration(file_path):
 def build_atempo_filter(factor):
     """Builds a chained atempo filter for FFmpeg to handle extreme speed changes."""
     filters = []
-    # FFmpeg's atempo filter is limited to the range [0.5, 100.0]
     while factor > 100.0:
         filters.append("atempo=100.0"); factor /= 100.0
     while factor < 0.5:
@@ -217,10 +216,8 @@ def decode_base64_to_tempfile(data_obj):
     if not data_obj or 'data' not in data_obj:
         return None
     
-    # Gradio sends base64 data in the format "data:video/mp4;base64,xxxx..."
     header, encoded_data = data_obj['data'].split(",", 1)
     file_extension = header.split('/')[1].split(';')[0]
-    
     decoded_data = base64.b64decode(encoded_data)
     
     with tempfile.NamedTemporaryFile(delete=False, suffix=f".{file_extension}") as tmp_file:
@@ -236,10 +233,8 @@ def merge_audio_to_video(video_input, audio_input):
     temp_files_to_clean = []
 
     try:
-        # --- Handle UI call (inputs are file paths) ---
         if isinstance(video_input, str) and os.path.exists(video_input):
             video_path = video_input
-        # --- Handle API call (inputs are base64 dictionaries) ---
         elif isinstance(video_input, dict):
             print("API call detected: Decoding video from base64.", flush=True)
             video_path = decode_base64_to_tempfile(video_input)
@@ -252,7 +247,6 @@ def merge_audio_to_video(video_input, audio_input):
             audio_path = decode_base64_to_tempfile(audio_input)
             if audio_path: temp_files_to_clean.append(audio_path)
 
-        # --- Validation ---
         if not video_path or not audio_path:
             return None, "Error: Missing video or audio file. Please provide both."
 
@@ -265,7 +259,6 @@ def merge_audio_to_video(video_input, audio_input):
         if video_duration == 0:
             return None, "Error: Input video has zero duration."
 
-        # --- Core FFmpeg Logic ---
         speed_factor = audio_duration / video_duration
         atempo_filter = build_atempo_filter(speed_factor)
         
@@ -296,7 +289,6 @@ def merge_audio_to_video(video_input, audio_input):
         return output_path, "✅ Audio merged successfully!"
 
     finally:
-        # --- Cleanup ---
         print(f"Cleaning up {len(temp_files_to_clean)} temporary files...", flush=True)
         for f in temp_files_to_clean:
             try:
@@ -308,10 +300,22 @@ def merge_audio_to_video(video_input, audio_input):
 # 3. Gradio Interface
 # ---------------------------------------------------------
 
+# --- THIS IS THE FIX ---
+# Define the default code before it is used in the UI.
+DEFAULT_CODE = """from manim import *
+
+class GenScene(Scene):
+    def construct(self):
+        c = Circle(color=BLUE, fill_opacity=0.5)
+        self.play(Create(c))
+        self.wait(1)
+"""
+
 with gr.Blocks(title="Manim Render & Audio Tool") as demo:
     with gr.Tab("🎬 Manim Video Renderer"):
         with gr.Row():
             with gr.Column(scale=1):
+                # The 'value' parameter now has a defined variable to reference.
                 code_input = gr.Code(label="Python Code", language="python", value=DEFAULT_CODE, visible=True)
                 orientation_opt = gr.Radio(choices=["Landscape (16:9)", "Portrait (9:16)"], value="Portrait (9:16)", label="Orientation", visible=True)
                 quality_opt = gr.Dropdown(choices=["Preview (360p)", "480p", "720p", "1080p", "4k"], value="Preview (360p)", label="Quality", visible=True)
@@ -336,7 +340,6 @@ with gr.Blocks(title="Manim Render & Audio Tool") as demo:
         with gr.Row():
             with gr.Column():
                 video_input_audio_tab = gr.Video(label="Input Video (MP4)")
-                # For the API, this audio component will accept base64 data
                 audio_input_audio_tab = gr.Audio(label="Input Audio", type="filepath")
                 merge_audio_btn = gr.Button("Merge Audio", variant="primary")
             with gr.Column():