How do I set Unity Recorder Accumulation (Samples, Shutter Interval, Shutter Profile) to get film-style motion blur, and what must I switch off first?

Problem. Real-time motion blur from a post-process is applied to the final frame, so a film render from Unity needs true sub-frame motion blur. Conditions. HDRP project, Movie or Image Sequence Recorder, Game View or Targeted Camera source (Recorder 5.1.7 docs). Method. Enable Accumulation under Input; set Samples (sub-frames between two frames); set Shutter Interval above 0 (Normalized 0-1 or Angle 0-360 degrees, so a 180-degree angle corresponds to half the frame interval, my inference from the Angle option); choose Shutter Profile Range (trapezoid with two fully-open points) or Curve to weight sub-frames. Check 'Effective number of accumulated samples', which can be lower than Samples when the interval is short. Disable the HDRP Motion Blur post-process and HDRP anti-aliasing first; use the Anti-aliasing toggle inside Accumulation instead. Failure modes. Leaving HDRP motion blur on stacks it over the accumulated blur. Limitations. Interval 0 turns motion-blur accumulation off. This is the engine-capture counterpart of the shutter controls in Unreal Movie Render Queue (C3-B721-12), and Cinemachine camera moves (C3-B721-04/05) are the motion that gets blurred. Version/date. Recorder 5.1.7 docs, fetched 2026-10-24. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: The docs do not state that Angle equals a physical film shutter angle; that mapping and the 180-degree example are my inference. No render was run. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://docs.unity3d.com/Packages/com.unity.recorder@5.1/manual/RecordingAccumulationMotionBlur.html",
      "note": "Accumulate motion blur; Accumulation properties: Samples; Known issues: motion blur; Angle option"
    },
    {
      "url": "https://docs.unity3d.com/Packages/com.unity.recorder@5.1/manual/RecorderAccumulationProperties.html",
      "note": "Accumulate motion blur; Accumulation properties: Samples; Known issues: motion blur; Angle option"
    },
    {
      "url": "https://docs.unity3d.com/Packages/com.unity.recorder@5.1/manual/KnownIssues.html",
      "note": "Accumulate motion blur; Accumulation properties: Samples; Known issues: motion blur; Angle option"
    }
  ]
}