[Justin]

Hmm testing here on macOS 10.13.6, all 64-bit, I found that with a 1 second, 10fps h264 video generated by AVFoundation:

VLC 3.0.0 and 3.0.4 (standalone) drop the last 5 frames (I only see the first 5 frames).
VLC 2.2.0 (standalone) plays all 10 frames
Quicktime player plays all 10 frames


REAPER / VLC 3.0.0 and 3.0.4 drop the last 6 frames (one more than the VLC app, hmm)
REAPER / VLC 2.2.0 drops the last 4 frames
REAPER / AVFoundation plays all 10 frames
REAPER / ffmpeg58 plays 9/10 frames


Edit: I have a fix for the 9/10 frames of ffmpeg58 (and 57), in the next builds it should show all frames (at least for this test).
Edit: I've gotten VLC 2.2 and VLC 3.0.4 to produce 9/10 frames (the VLC 3.0.4 issue with dropping so many frames is a bug in in the avcodec module of VLC, which one can workaround, I wonder if it's been fixed yet in the latest VLC git, hmm...)