一套简洁的字幕压制工具链。
A simple toolchain for burn subtitles into mp4 video (hardcode embed).
This script use Chromium + Pyppeteer for rendering subtitle images, and OpenCV + numba JIT to attach subtitles to video frames, then output the video. Finally it invokes ffmpeg to adjust bitrate and append audio track.
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English text use
Candarafont, and Chinese text use黑体font by default. Code uses theFira Codefont. -
Code is colored bright blue (#B7F5F7), whereas plain text is white (#FFFFFF).
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Add semi-transparent rectangle shade by default.
This script support the extended .sub format, i.e:
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Full Markdown syntax, including HTML elements / tags
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Render LaTeX math formula by KaTeX
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Multi-line or irregular shape multi-line structures, to trigger the multi-line elements of the first two
Please install ffmpeg.
The subtitle which to be burned should be in .sub format, the start / end time should be indicated by frame. One typical line of .sub should be:
{7261}{7287}例子 Example 例子
When trigger multi-line structures, you should append a [ml] / [multiline] identifier after the {}{}, then provide a legal Python string.
By using this toolchain, you can burn a major subtitle (located in the bottom center) and a minor subtitle (located in the top center).
The major subtitle should be named as major.sub; or you can modify it in render_subtitle.py.
The minor subtitle should be named as minor.sub; or you can modify it in render_subtitle.py.
Best performance when provide a 1920x1080 video input.
Get the subtitle file ready, then run render_subitle.py to render subtitle images.
After finished, invoke ffmpeg to extract audio. (Assume that original video is named lec.mp4)
ffmpeg -i lec.mp4 -vn -acodec copy myaudio.m4aThen execute py render_video_opencv.py --chunk-size 500 --input lec.mp4.
(When CHINK_SIZE is set to 500, render an video of 1920x1080 resolution takes 7GiB memory. Please modify to an appropriate value.)
(Execute py render_video_opencv.py -h to see help and all options)
Finally, ensure the extracted audio is in the same folder with output video. Then modify the video filename below, and execute this command. The filename output1.mp4 is the default output filename of the previous step:
ffmpeg -i output1.mp4 -i myaudio.m4a -c:v copy -c:a aac -strict experimental -b:v 500k -pix_fmt yuv420p -c:v libx264 output.mp4 -yor just execute generate_final_video.py to generate final video. Video filename is also output1.mp4 by default.
You can modify PAGE_COUNT value in render_subtitle.py to the parallel pages of rendering subtitle.
使用 Chromium + Pyppeteer 渲染字幕图像，然后使用 OpenCV + numba JIT 将字幕逐帧附加到视频图片上并输出视频。使用 ffmpeg 调整码率并附加音频。
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默认中文字体为
黑体，英文字体为Candara，代码字体为Fira Code Regular -
默认代码颜色为亮蓝色（#B7F5F7），普通字颜色为纯白色（#FFFFFF）
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默认支持半透明背景
支持扩展的 .sub 字幕格式，即：
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支持完整的 Markdown 语法，包括内嵌 HTML 元素。
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支持通过 KaTeX 渲染 LaTeX 数学公式
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支持多行 / 不规则形状多行结构，用于触发前两者的多行语法
请安装 ffmpeg。
准备压制的字幕文件应为 .sub 格式，按帧标明出现 / 消失时间。.sub 典型的一行格式如：
{7261}{7287}例子 Example 例子
触发多行结构时，应在 {}{} 后加入标识符 [ml] 或 [multiline]，然后提供一个合法的 Python 字符串表达式。
工具链支持位于下方的主字幕和位于上方的副字幕。
主字幕文件名应为 major.sub；或在 render_subtitle.py 中修改 MAJOR_FILENAME。
副字幕文件名应为 minor.sub；或在 render_subtitle.py 中修改 MINOR_FILENAME。
视频分辨率为 1920x1080 时，渲染效果最好。
准备好字幕文件后，运行 render_subtitle.py 渲染字幕。
等待完成后，使用 ffmpeg 提取原始视频文件的音频。（假设原始视频命名为 lec.mp4）
ffmpeg -i lec.mp4 -vn -acodec copy myaudio.m4a然后执行 py render_video_opencv.py --chunk-size 500 --input lec.mp4。
（CHUNK_SIZE 为 500 时，1920x1080 分辨率的视频约占用 7GiB 内存，请酌情修改。）
（使用 py render_video_opencv.py -h 查看帮助和所有选项）
确保音频文件和生成的视频处于同一目录，之后修改下列命令中输入输出视频的文件名，并执行。此命令默认视频文件名为 output1.mp4（即上步的输出视频名），也可自行修改：
ffmpeg -i output1.mp4 -i myaudio.m4a -c:v copy -c:a aac -strict experimental -b:v 500k -pix_fmt yuv420p -c:v libx264 output.mp4 -y或运行 generate_final_video.py 生成最终视频。默认视频名也为 output1.mp4。
在 render_subtitle.py 内，可修改 PAGE_COUNT 为并行渲染字幕的页面数。