Python结合FFmpeg实现将MP4视频与SRT字幕无损合并

sudo apt install ffmpeg

brew install ffmpeg

ffmpeg -version

ffmpeg -sub_charenc UTF-8 \
-i input.mp4 \
-i subtitle.srt \
-c:v copy \
-c:a copy \
-c:s mov_text \
-metadata:s:s:0 language=chi \
output.mp4

import subprocess
import os
import sys

def validate_file(file_path, file_type="file"):
    """
    校验文件是否存在
    :param file_path: 文件路径
    :param file_type: 文件类型描述（用于错误提示）
    """
    if not os.path.exists(file_path):
        raise FileNotFoundError(f"{file_type} 不存在: {file_path}")
    print(f"{file_type} 校验通过: {file_path}")
    return True


def merge_video_with_subtitles(video_path, srt_path, output_path):
    """
    使用 FFmpeg 将 MP4 视频与 SRT 字幕合并
    不重新编码视频和音频，支持 UTF-8 中文字幕
    """

    # 1. 校验输入文件是否存在
    validate_file(video_path, "视频文件")
    validate_file(srt_path, "字幕文件")

    # 2. 构建 FFmpeg 命令
    ffmpeg_cmd = [
        "ffmpeg",

        # 输入视频文件
        "-i", video_path,

        # 输入字幕文件
        "-i", srt_path,

        # 视频流直接拷贝，不重新编码
        "-c:v", "copy",

        # 音频流直接拷贝，不重新编码
        "-c:a", "copy",

        # 将 SRT 转换为 MP4 支持的 mov_text 字幕格式
        "-c:s", "mov_text",

        # 设置字幕语言元数据为中文
        "-metadata:s:s:0", "language=chi",

        # 输出文件
        output_path
    ]

    # 3. 强制指定字幕编码为 UTF-8，防止中文乱码
    ffmpeg_cmd.insert(3, "-sub_charenc")
    ffmpeg_cmd.insert(4, "UTF-8")

    try:
        # 4. 执行 FFmpeg 命令
        result = subprocess.run(
            ffmpeg_cmd,
            check=True,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            text=True
        )
        print(f"字幕合并成功，输出文件: {output_path}")

    except subprocess.CalledProcessError as e:
        # FFmpeg 执行失败时输出错误信息
        print("FFmpeg 执行失败:")
        print(e.stderr)
        raise

    except Exception as e:
        # 其他异常
        print(f"执行过程中发生错误: {e}")
        raise


def main():
    """
    主函数，定义输入输出路径
    """

    # 视频文件路径
    video_path = r"SSYouTube.online_Gesture Drawing Practice _ 20 and 40 sec. poses_1080p.mp4"

    # 字幕文件路径
    srt_path = r"SSYouTube.online_Gesture Drawing Practice _ 20 and 40 sec. poses_1080p.srt"

    # 输出视频路径
    output_path = "output.mp4"

    # 合并视频与字幕
    merge_video_with_subtitles(video_path, srt_path, output_path)


if __name__ == "__main__":
    try:
        main()
    except Exception as e:
        print(f"程序异常退出: {e}")
        sys.exit(1)

validate_file(video_path, "video")
validate_file(srt_path, "subtitle")

-sub_charenc UTF-8

-vf subtitles=xxx.srt