Create app.py

app.py

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+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import subprocess
+import gradio as gr
+import tempfile
+
+# Define supported subtitle formats
+SUPPORTED_SUBTITLE_FORMATS = ['srt', 'vtt', 'ass', 'ssa']
+SUPPORTED_SUBTITLE_FORMATS2 = ['srt', 'vtt', 'ass', 'ssa']
+
+def convert_subtitle_file(src_format, dest_format, input_file_path):
+    """
+    Convert the subtitle file from src_format to dest_format using ffmpeg.
+    
+    Parameters:
+        src_format (str): The source subtitle format.
+        dest_format (str): The target subtitle format.
+        input_file_path (str): Path to the input subtitle file.
+        
+    Returns:
+        tuple: (converted_file_path, error_message)
+    """
+    # Create a temporary file to store the converted subtitle
+    output_file = tempfile.NamedTemporaryFile(delete=False, suffix=f".{dest_format}")
+    output_file_path = output_file.name
+    output_file.close()  # Close the file so that ffmpeg can write to it
+
+    # Construct the ffmpeg command; the -y flag overwrites the output file if it exists
+    cmd = [
+        "ffmpeg",
+        "-y",
+        "-i", input_file_path,
+        output_file_path
+    ]
+    try:
+        subprocess.run(cmd, check=True, capture_output=True, text=True, encoding='utf-8')
+        return output_file_path, ""
+    except subprocess.CalledProcessError as e:
+        return "", e.stderr
+
+def convert_subtitles(uploaded_file_path, dest_format):
+    """
+    Convert the uploaded subtitle file to the specified format.
+    
+    Parameters:
+        uploaded_file_path (str): Path to the uploaded subtitle file.
+        dest_format (str): The target subtitle format.
+    
+    Returns:
+        tuple: (converted_file_path, error_message)
+    """
+    if uploaded_file_path is not None:
+        # Determine the source format from the file extension (converted to lowercase)
+        src_format = uploaded_file_path.split('.')[-1].lower()
+
+        if src_format not in SUPPORTED_SUBTITLE_FORMATS:
+            return "", "Unsupported file format. Please upload a valid subtitle file (supported: srt, vtt, ass, ssa)."
+
+        try:
+            converted_file_path, error_message = convert_subtitle_file(src_format, dest_format, uploaded_file_path)
+            if converted_file_path:
+                return converted_file_path, ""
+            else:
+                return "", f"Error during conversion: {error_message}"
+        except Exception as e:
+            return "", f"Error during conversion: {e}"
+    return "", "No file uploaded."
+
+def main():
+    # Create the Gradio Blocks interface with a page title for SEO
+    with gr.Blocks(analytics_enabled=False, title="Free Online Subtitle Converter - Convert SRT, VTT, ASS, SSA Subtitles Easily") as demo:
+        
+        # Load custom CSS to improve the UI appearance
+        demo.load_css("""
+        /* Global background and font settings */
+        body {
+            background-color: #f7f7f7;
+            font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
+        }
+        /* Main container styling */
+        .gradio-container {
+            max-width: 900px;
+            margin: auto;
+            background-color: #ffffff;
+            border-radius: 8px;
+            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
+            padding: 20px;
+        }
+        /* Convert button styling */
+        #convert-btn {
+            background-color: #007bff;
+            color: #ffffff;
+            border: none;
+        }
+        #convert-btn:hover {
+            background-color: #0056b3;
+        }
+        """)
+
+        # Add SEO information, application description, and usage instructions
+        with gr.Row():
+            with gr.Column():
+                gr.Markdown(
+                """
+                # Free Online Subtitle Converter
+
+                **Subtitle Converter** is a simple and easy-to-use online tool that supports converting subtitle files between SRT, VTT, ASS, and SSA formats.  
+                This application leverages [ffmpeg](https://ffmpeg.org/) for subtitle format conversion, making it ideal for various subtitle conversion needs.
+
+                ## Application Overview
+                - **Fast Conversion**: Upload your file and get the conversion done in seconds.
+                - **Multiple Formats Supported**: Supports srt, vtt, ass, ssa formats.
+                - **Online Tool**: No need to install any software; use it directly from your browser.
+
+                ## Usage Instructions
+                1. Upload a subtitle file (supported formats: srt, vtt, ass, ssa) from the left side.
+                2. Select the desired target format from the dropdown menu.
+                3. Click the "Convert" button to initiate the conversion.
+                4. Once the conversion is complete, click the "Download Converted File" button to download your file.
+                """
+                )
+
+        # Build the upload and conversion operation area
+        with gr.Row():
+            # Left column: file upload and format selection
+            with gr.Column(scale=1):
+                file_input = gr.File(label="Upload Subtitle File", file_types=SUPPORTED_SUBTITLE_FORMATS, type="filepath")
+                dest_format = gr.Dropdown(label='Convert To', choices=SUPPORTED_SUBTITLE_FORMATS2, value=SUPPORTED_SUBTITLE_FORMATS2[0])
+                convert_button = gr.Button("Convert", elem_id="convert-btn")
+            # Right column: display conversion result and error messages
+            with gr.Column(scale=1):
+                result_file = gr.File(label="Download Converted File", visible=True)
+                error_message = gr.Textbox(label="Error Message", visible=False, interactive=False)
+                # Download button for the converted file
+                download_button = gr.DownloadButton(
+                    label="Download Converted File",
+                    value=None,
+                    visible=True,
+                    variant="primary",
+                )
+
+        def convert_and_show(uploaded_file_path, dest_format):
+            """
+            Process the uploaded file conversion and return the conversion result or error message.
+            
+            Parameters:
+                uploaded_file_path (str): Path to the uploaded subtitle file.
+                dest_format (str): Target format for conversion.
+            
+            Returns:
+                tuple: (converted_file_path, updated error message, download button value)
+            """
+            if not uploaded_file_path:
+                return None, gr.update(value="Please upload a subtitle file.", visible=True), None
+            if not dest_format:
+                return None, gr.update(value="Please select a target format.", visible=True), None
+
+            file_path, error = convert_subtitles(uploaded_file_path, dest_format)
+            if file_path:
+                # Conversion successful, hide error message and update download link
+                return file_path, gr.update(visible=False), file_path
+            else:
+                return None, gr.update(value=error, visible=True), None
+
+        # Bind the click event to the convert function
+        convert_button.click(fn=convert_and_show, inputs=[file_input, dest_format], outputs=[result_file, error_message, download_button])
+
+        # Footer information
+        gr.Markdown(
+        """
+        ---
+        **Disclaimer**: This tool is intended for subtitle format conversion only. Please ensure you have the legal rights to use the uploaded files.
+        """
+        )
+
+    # Launch the app without specifying a fixed port, making it suitable for Linux and Hugging Face Spaces
+    demo.launch(share=True)
+
+if __name__ == "__main__":
+    main()