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• v2 b81b50199a

  Patch webrtcsink to put no converter in front of mpph264enc

  Ghost released this 2026-08-25 08:43:05 +00:00 | 1 commits to main since this release

  make_converter_for_video_caps builds the chain webrtcsink inserts ahead of an
  encoder it selected, special-casing hardware it knows — NVMM, D3D11, CUDA, GL,
  VA, and on main also v4l2h264enc — and falling back to software
  videoconvert ! videoscale for anything else. Rockchip's MPP encoder takes
  NV12, I420, YUY2 and more directly and converts on the SoC's 2D accelerator, so
  the fallback adds a full CPU pass over every frame to do work the hardware was
  going to do anyway, on the four A55s robotd's 50 Hz loop shares.

  The reason this matters more than CPU: the robot currently avoids the whole
  question by pre-encoding and handing webrtcsink finished H.264. That works, and
  it means webrtcsink cannot reach the encoder — so congestion control cannot
  adapt the bitrate to the link, and a peer's PLI cannot produce a keyframe, which
  leaves a viewer that lost one broken until the next periodic GOP. Letting
  webrtcsink own the encoder fixes both. This patch is what makes that affordable.

  This repository is no longer patch-free, and says so. MPL-2.0 asks that
  modifications be identifiable, so the README states it, patches/README.md gives
  each patch's reasoning, and build.sh records every applied patch in the release
  MANIFEST beside the upstream ref. git apply --check runs first, so a patch that
  stops applying fails the build naming itself rather than yielding a plugin
  quietly missing the change it was carried for.

  The trade-off is written down rather than glossed: without videoscale the bin
  cannot resize, so the negotiated resolution must be one the source produces.
  True on this robot, which pins its caps upstream of the tee — and the reason
  upstream may want RGA-backed scaling instead of nothing before taking it. The
  v4l2h264enc arm on main is the same shape for another hardware encoder, so the
  precedent exists, and if it lands this file is deleted at the next bump.

  Verified to apply cleanly against a real 0.15.3 checkout.

  Assisted-by: Claude:claude-opus-5[1m] shellcheck

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