-force_key_frames asks for a keyframe every 3 s, but h264_nvenc inserts
those as plain I-frames unless -forced-idr is set. The HLS muxer only
splits on IDR frames, so NVENC transcodes fell back to the encoder's
default 250-frame GOP: 8.34 s segments at 29.97 fps, ~10 s at 25 fps.
On prod ~480 playlists have a target duration above 4 s. Long segments
mean more data before playback starts and coarser seeks.
Verified on a 10 s 29.97 fps clip: segments went from 8.34 + 1.67 s to
3.003 x 3 + 1.001 s, matching the libx264 path, which was already
correct.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Cameron CordesandClaude Opus 5.5
0b87320ef7