Re-vendor fdanyone at the B-frame-free encoder

Picks up the pipeline's own `bf=0` on `write_video`, so the mp4s on disk
carry no B-frames in the first place. Belt and braces: the Rerun reader
strips them anyway on the way into a VideoStream, but a target video that
never had them is one fewer transcode and one fewer thing to reason about.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

PROVENANCE.md

@@ -6,8 +6,8 @@
 | --- | --- |
 | Source repository | <https://github.com/pablovela5620/4DAnyone-5090> |
 | Branch | `space-streaming` |
-| Commit | `0cc334c2b260ff19b23d423ac8123d318ed602ff` |
-| Synced | 2026-08-27T05:15:32Z |
+| Commit | `8ac42505d39533e01504b7749ca36474f60fba44` |
+| Synced | 2026-08-27T16:27:49Z |
 
 ## Excluded from the copy
 

fdanyone/video.py

@@ -442,7 +442,8 @@ def write_video(
         stream.width = width
         stream.height = height
         stream.pix_fmt = "yuv420p"
-        stream.options = {"crf": str(crf), "preset": preset}
+        # No B-frames: Rerun's web VideoStream decoder cannot reorder them.
+        stream.options = {"crf": str(crf), "preset": preset, "bf": "0"}
         for index, rgb in enumerate(itertools.chain((first,), iterator)):
             if rgb.shape != first.shape:
                 raise VideoContractError(f"Frame {index} has shape {rgb.shape}, expected {first.shape}.")