Live Stream Replay uses a background shadow recording — a second, lower-bitrate video file written to temporary storage while you stream. When you trigger a replay, this buffer is what gets played back.

When shadow recording actually runs:

• Streaming only (no local recording): Shadow recording is active.
• Streaming and recording at the same time: Shadow recording is not active — the main recording file is used as the replay source, so there is zero additional overhead in this mode.
• Streaming with Space Saver mode: Shadow recording is active (Space Saver clips are fragmented and can’t be used directly for replay).

How much extra CPU does it use?

When shadow recording is running, ScoreCam runs two simultaneous H.264 hardware encoders. However, it is not double the work:

• The GPU compositing is already happening for the live stream — the shadow recorder reuses the same processed frames with no extra rendering.
• The shadow file is encoded at a much lower bitrate (~750 Kbps vs. 2–4 Mbps typical for the stream), so the second encode pass is lighter than the first.

In practice, expect roughly 10–20% additional CPU when shadow recording is active. The bigger concern on long events is thermal throttling: two concurrent encode sessions generate more heat, which can cause the device to reduce performance over time. If you notice frame rate drops during long streams, try disabling Live Stream Replay (App Settings › Live Stream Replay) when you don’t need it.