Canon EOS RP Mirrorless Camera - Manual (Page 279)

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Recording Video Snapshots
General Video Snapshot Precautions
o No sound is recorded when you set [Playback effect] to [1/2x speed] or [2x
speed] .
o Recording time per video snapshot is only approximate. It may differ slightly
from the actual recording time indicated during playback, due to the frame rate
and other factors.