yt-dlp-danmaku

yt-dlp plugin for converting Bilibili danmaku into ASS format. Powered by biliass.

Installation and upgrading

Requires yt-dlp 2023.01.02 or above.

You can install or upgrade this package with pip:

pip install -U yt-dlp-danmaku

Usage

Download video along with the ASS subtitle

yt-dlp --write-subs --use-postprocessor danmaku https://www.bilibili.com/video/BV1Sm4y1N78J

Download video embedded with danmaku as a subtitle stream

Bilibili videos are originally mp4 format, but this format does not support ASS subtitle. Therefore, you need to use another format that supports it, such as mkv:

yt-dlp --embed-subs --use-postprocessor danmaku --remux-video mkv https://www.bilibili.com/video/BV1Sm4y1N78J

You can then try playing this video with players that support ASS subtitles, such as mpv and VLC.

Download video and "burn" the danmaku onto it

You need to run FFmpeg yourself to do this. Here is an example how you can do that:

yt-dlp --write-subs --use-postprocessor danmaku --output input https://www.bilibili.com/video/BV1Sm4y1N78J
ffmpeg -i input.mp4 -vf subtitles=input.danmaku.ass output.mp4
rm input.mp4 input.danmaku.ass

Get ASS subtitle without downloading the video

yt-dlp --write-subs --use-postprocessor danmaku:when=before_dl --skip-download https://www.bilibili.com/video/BV1Sm4y1N78J

Use with mpv

mpv --script-opts=ytdl_hook-ytdl_path=yt-dlp --ytdl-raw-options=use-postprocessor=danmaku:when=before_dl,write-subs=,no-simulate=,skip-download= https://www.bilibili.com/video/BV1Sm4y1N78J

You can turn on and off danmaku by using j (by default). Add --sid=1 to turn on danmaku on start. You can add these options to your mpv config file.

Notice: this will leave an ASS file in the current directory. Delete it afterwards if you do not want it.

Configuration

You can pass options to this plugin. For example, to set the opacity of danmaku texts to 0.1 and reserve the bottom half, use --use-postprocessor danmaku:text_opacity=0.1;display_region_ratio=0.5. All available options:

Option	Default	Meaning
lang	danmaku	Language selector; you do not normally need to set this
display_region_ratio	1.0
font_face	sans-serif
font_size	25
text_opacity	0.8
duration_marquee	15
duration_still	10
block_top	false
block_bottom	false
block_scroll	false
block_reverse	false
block_fixed	false
block_special	false
block_colorful	false
block_keyword_patterns
reduce_comments	false

Run biliass -h for more information about these options.

Development

See the Plugin Development section of the yt-dlp wiki.

License

MIT.