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