Rerun Mp4
Ingest .mp4 video into Rerun chunk streams with rerun.experimental.Mp4Reader.
Install
npx skills add rerun-io/rerun --skill rerun-mp4 -g -a claude-code -y- Repository
- rerun-io/rerun11.7k
- Category
- Media
- Updated
- 3d ago
- License
- Apache-2.0
- Context cost
- Mediumabout 3,000 tokens
- Runs scripts
- No, instructions only
What it does
Ingest .mp4 video into Rerun chunk streams with rerun.experimental.Mp4Reader. Read when converting video into a VideoStream, choosing stream vs asset mode, transcoding (B-frames, output codec, GOP size) through FFmpeg, or aligning video PTS onto a recording's wall-clock timeline. Builds on rerun-chunk-processing (stream mechanics) and rerun-data-model (where the video belongs in the recording).
Rerun mp4 ingestion
Mp4Reader turns one .mp4 file into a lazy chunk stream on one entity:
compressed video samples, no decode to pixels, nothing re-encoded unless it has
to be. Everything is configured on the constructor; stream() takes no
arguments. Stream mechanics after .stream() (filter, map, merge, collect,
write) are in rerun-chunk-processing.
The API
from rerun.experimental import Mp4Reader, Mp4TranscodeOptions
reader = Mp4Reader(video_path, entity_path="/camera/front") # mode="stream" by default
stream = reader.stream() # lazy: nothing is decoded yet
Every parameter after path is keyword-only. One reader handles one file, for
several cameras, build one reader per file and LazyChunkStream.merge(...) them
(see below).
Two modes
mode | emits | when |
|---|---|---|
"stream" (default) | a codec chunk, per-GOP sample chunks, a keyframe marker | almost always, every frame is time-indexed and queryable |
"asset" | the whole file as one blob, plus a frame index | the codec cannot be a VideoStream, or the source starts mid-GOP |
Reach for stream mode; the next section covers exactly what it emits. Asset mode
copies the entire file into the recording as one blob, so nothing downstream can
look at a single frame without the whole asset. It is the fallback for codecs a
VideoStream cannot carry (mp4v, image-sequence mp4), and it is what rerun video.mp4 and the built-in file importer use.
What stream mode emits
For tests/assets/video/Big_Buck_Bunny_1080_1s_h264_nobframes.mp4 (30 frames,
one GOP) with entity_path="/camera/front", the whole output is three chunks:
