import subprocess
from pathlib import Path


def convert_to_h264(input_root: Path, vid_full_name: str, output_root: Path) -> str:
    """
    将视频文件转码为 H.264 编码格式

    Args:
        input_path: 输入视频文件路径（相对或绝对路径）
        output_path: 输出视频文件路径（可选，默认为输入文件同名_h264.mp4）

    Returns:
        转码后的视频文件路径

    Raises:
        FileNotFoundError: 输入文件不存在
        subprocess.CalledProcessError: FFmpeg 转码失败
    """
    input_path_all = Path(input_root,vid_full_name).resolve()
    output_vid_full_name = f"{Path(vid_full_name).stem}_h264.mp4"
    output_path_all = Path(output_root, output_vid_full_name).resolve()

    if not input_path_all.exists():
        raise FileNotFoundError(f"输入文件不存在：{input_path_all}")

    print(f"开始转码：{input_path_all}")

    cmd = [
    "ffmpeg",
    "-i", str(input_path_all),
    "-c:v", "h264_nvenc",  # NVIDIA 硬件编码
    "-c:a", "aac",
    "-b:a", "128k",
    "-y",
    str(output_path_all)
]

    result = subprocess.run(cmd, capture_output=True, text=True)

    if result.returncode != 0:
        raise subprocess.CalledProcessError(
            result.returncode,
            cmd,
            result.stdout,
            result.stderr
        )
    print(f"转码完成：{output_path_all}")
    return str(output_path_all)