The video codec. HEVC (High Efficiency Video Coding) x265 is the successor to x264 (AVC). It achieves roughly 50% better compression at the same visual quality. For a 4K HDR film like Your Name. , x265 is essential — it keeps file sizes manageable (often 15–30 GB for a high-quality encode, versus 60+ GB for a raw remux) while preserving fine details, film grain (or in this case, digital noise/texture), and HDR metadata.