Improve frame metadata handling in video converter

[oyekamal]

Summary

• load frameCreationInfo.json within main after CLI parsing and validate file presence
• pass parsed metadata into convert_frames_to_video and add optional cv2 dependency injection for testing
• provide user-friendly errors for missing metadata, missing first frame, and incomplete metadata entries

Testing

• python -m compileall core/frame_to_video.py

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https://chatgpt.com/codex/tasks/task_b_68ecc92365b0832fb52fb039ec66ea78

[Copilot]

Pull Request Overview

This PR refactors the video conversion logic to improve metadata handling by removing global frame data loading and adding proper error handling. The changes move frame metadata loading into the main function after CLI parsing and add validation for file presence and completeness.

• Moved frame metadata loading from global scope to main function with proper error handling
• Added dependency injection for cv2 module to improve testability
• Implemented comprehensive validation for metadata structure and frame file existence

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[Copilot]

The error message spans two lines with incorrect string concatenation. The space should be included in the f-string to avoid 'Error: First frame not found at{path}' output.

Suggested change

	"Error: First frame not found at"
	f" {first_frame_path}. Please ensure frames are generated."
	f"Error: First frame not found at {first_frame_path}. Please ensure frames are generated."

[Copilot]

Using string concatenation for file paths can cause issues on different operating systems. Use os.path.join(pathIn, first_frame_key + '.png') instead for cross-platform compatibility.

[Copilot]

Using string concatenation for file paths can cause issues on different operating systems. Use os.path.join(pathIn, frame_key + '.png') instead for cross-platform compatibility.