Videos

A video is the center of bilibili, and four commands cover it: video for metadata, related for what sits next to it, streams for playable URLs, and danmaku for bullet-chat. All four accept any id form (BV…, av…, or a full watch URL).

Metadata

bili video BV17x411w7KC

The table view shows the headline fields; -o json is the full lossless record, including the owner, statistics, dimensions, and every part (page) of a multi-part video.

video takes more than one id at once, and reads ids from stdin with -, so it composes with any command that emits URLs:

bili video BV17x411w7KC BV1xx411c7XW       # several at once
bili search lofi -o url | bili video -      # everything a search found

Multi-part videos

Many videos have several parts, each with its own cid. The streams and danmaku commands work on one part at a time and default to the first. Pick another with -p, which is 1-based and counts parts the way the site labels them, P1, P2 and so on:

bili video BVID -o json        # look at the "pages" array for the parts
bili danmaku BVID -p 2         # bullet-chat for the second part
bili streams BVID -p 2         # the streams for that same part

--page is the global pagination flag and has nothing to do with parts, so it is -p you want here.

Related videos

bili related BV17x411w7KC
bili related BV17x411w7KC -o url     # just the watch URLs

This is the same list bilibili shows alongside a video, which makes it the natural edge to follow when crawling.

Streams

bili streams BV17x411w7KC

streams lists the playable media URLs the API exposes for a part, with their quality, codec, and format. Use --quality to ask for a specific level. These are the URLs the player would use; streams itself downloads nothing and decrypts nothing, it reports what is offered.

Download audio

bili download BV17x411w7KC
bili download BV17x411w7KC --parts 1-3 --format mp3
bili download BV17x411w7KC --format flac --output-dir ~/Music

download wraps BBDown rather than reimplementing it. BBDown already handles the DASH manifest, the stream selection, the multi part handling and the merge, and a second Go implementation of all that would be a second thing to maintain that does the same job worse. What bili adds is the part BBDown does not: whatever you paste is resolved to a bvid first, so a URL, a bare av number and a bvid all work here exactly as they do in every other command, and an id for a bangumi or an audio track is refused by name rather than becoming a BBDown error about a page that does not exist.

m4a is what BBDown emits and involves no second process. mp3, flac and wav are transcoded with ffmpeg once the download finishes. --quality sets the mp3 bitrate preset, from best to worst, and is ignored for flac and wav, where a lossless format leaves it nothing to mean.

--parts takes BBDown's own selection syntax, 1,3-5,LAST and the like, and is passed straight through, as are --file-pattern and --multi-file-pattern. BBDown writes into a staging directory and finished files are moved into place from there, so a run that fails halfway leaves nothing behind in the directory you pointed at.

The two binaries

Neither BBDown nor ffmpeg is bundled, vendored or installed for you. Both are looked up on PATH, and --bbdown-bin and --ffmpeg-bin point at a copy somewhere else, as do BILI_BBDOWN_BIN and BILI_FFMPEG_BIN. A missing one is reported before the transfer starts rather than after it, with the name of the binary and where to get it, because discovering that ffmpeg is absent at the end of a forty minute audiobook is a bad way to find out.

--dry-run prints the command that would run, quoted so it can be pasted into a shell, and runs nothing.

BBDown's progress output goes to the terminal as BBDown wrote it. bili does not parse it into a progress display of its own.

This command downloads audio. It does not download video, and it does not decrypt anything.

Bullet-chat

bili danmaku BV17x411w7KC

Each row is one comment that scrolls across the video: its progress_ms (the millisecond offset where it appears), mode, color, fontsize, and content. The data arrives as protobuf and bili decodes it into plain records, so it sorts, filters, and pipes like anything else:

bili danmaku BVID -o jsonl | jq -r 'select(.progress_ms < 10000) | .content'

See comments and danmaku for the conversation data in depth.