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Recording And Capture-Last

The stream page header contains recording controls for a single stream.

Recording Source (Continuous Only)​

The source dropdown controls what continuous recording records:

  • Multiplex output: the stream's multiplexed output.
  • Raw output: the raw stream output.
  • Undistorted output: the calibrated/undistorted host output when available.
  • Pipeline output: record a specific pipeline's host output port (when pipelines are attached and expose image outputs).

The source dropdown groups available pipeline outputs by pipeline.

Capture-last clips do not use this selection; they always capture from the stream's rolling shadow buffer (see below).

Continuous Recording​

  • Click Record to start recording.
  • Click Stop to stop.

Recording writes a Media item on the device (associated with the stream id).

Capture-Last Clips (5s / 30s / 1m)​

The 5s, 30s, and 1m buttons capture the last window of time from the rolling shadow buffer.

Requirements and behavior:

  • Shadow recorder must be enabled in the Stream tab (per stream).
  • Capture-last is disabled while continuous recording is active.
  • Captures are written as Media items on the device.

If capture fails with empty output, it usually means the shadow recorder is not running for that stream (disabled) or the stream/encoder pipeline is unhealthy.

Recording Settings​

The gear button opens recording settings, including:

  • Container: mp4 or raw. mp4 is broadly playable; raw is a raw H.264/H.265 elementary stream (Annex B) mainly for debugging and post-processing.
  • Codec: h264 or h265 for continuous recordings (defaults to H.265). Capture-last MP4 output is produced as H.265.
  • FPS: best-effort frame drop to hit a target rate (useful for reducing file sizes and CPU load).
  • Bitrate (bps): higher bitrate generally increases quality and file size (used when encoding/transcoding MP4).
  • GOP: keyframe interval. Smaller GOP can improve seeking and recovery at the cost of bitrate/quality efficiency.
  • Quality (CRF 0-51): lower is higher quality and larger files (commonly ~18-28). Used when encoding/transcoding MP4.
  • Include IMU: when enabled, continuous recording also stores a gzipped IMU sidecar file for the recording.

Notes:

  • The UI uses one shared settings panel for both continuous recording and capture-last. In practice, capture-last mainly cares about container; the clip comes from the shadow recorder buffer.
  • Some options only apply when MP4 output is being encoded/transcoded. If you choose raw, HeliOS writes the raw encoded bitstream (Annex B) for the chosen codec.