: A text file containing all the code blocks, variables, and project logic.
Ensure project.json is at the root level. Run the file through a JSON validator.
import zipfile import os import json def convert_zip_to_sb3(zip_path, output_sb3_path): """ Converts a structured ZIP archive into a verified, high-quality .sb3 file. """ if not os.path.exists(zip_path): print(f"Error: Source file zip_path not found.") return False # Temporary directory to validate structure temp_extract_dir = zip_path.replace('.zip', '_temp_extract') with zipfile.ZipFile(zip_path, 'r') as zip_ref: zip_ref.extractall(temp_extract_dir) # Verify project.json exists json_path = os.path.join(temp_extract_dir, 'project.json') if not os.path.exists(json_path): print("Error: Missing 'project.json' at the root of the archive.") return False # Build the SB3 Archive with zipfile.ZipFile(output_sb3_path, 'w', zipfile.ZIP_DEFLATED) as sb3_file: for root, dirs, files in os.walk(temp_extract_dir): for file in files: file_path = os.path.join(root, file) # Determine target path inside the archive (flattening structure) archive_name = os.path.relpath(file_path, temp_extract_dir) # Prevent nested folder structures inside SB3 if os.sep in archive_name: archive_name = os.path.basename(file_path) sb3_file.write(file_path, archive_name) # Clean up temporary files for root, dirs, files in os.walk(temp_extract_dir, topdown=False): for file in files: os.remove(os.path.join(root, file)) for room_dir in dirs: os.rmdir(os.path.join(root, room_dir)) os.rmdir(temp_extract_dir) print(f"Success: High-quality conversion saved to output_sb3_path") return True # Example Usage # convert_zip_to_sb3("my_scratch_backup.zip", "compiled_project.sb3") Use code with caution. Troubleshooting Common Conversion Failures zip to sb3 extra quality
An .sb3 file is not a unique, complex file type. It is actually a standard ZIP archive that has been renamed.
Custom scripts can automate the mapping of assets to JSON, ensuring the "extra quality" standard is met consistently. 5. Best Practices for "Extra Quality" sb3 : A text file containing all the code
Sample rate mismatch (e.g., 48kHz forced to 22kHz). Fix: Use Audacity to re-export audio as WAV (16-bit PCM, 44100Hz) before re-ZIPping.
Assuming you want to convert a Scratch project ZIP (or .zip containing project files) to a Scratch 3 .sb3 file with maximum quality (preserve assets), here’s a concise step-by-step: It is actually a standard ZIP archive that has been renamed
Select (do not select the parent folder itself). Right-click and choose Compress or Add to Archive . Set the archive format strictly to ZIP .
For Scratch developers, educators, and power users, converting projects from the compressed ZIP format back into the functional .sb3 format is a common necessity. While .sb3 files are fundamentally ZIP archives under a different extension, simply renaming the file extension does not always yield the "extra quality" or seamless performance required for complex projects.
Because an SB3 file is natively a ZIP archive, "converting" a ZIP to an SB3 is less about file transcoding and more about . The Blueprint of a Perfect SB3 Archive