A question about playing backwards

[wonkey_monkey]

I've just noticed that if I open an h264 MP4 in VirtualDub2, I can play backwards from any point quite smoothly, in a way that I can't when using FFMpegSource2().

I am right in thinking this is because VirtualDub2 caches any previous frames from the same GOP when you jump to some point on the timeline?

[shekh]

Yes, the principle is like that. This logic is in the "caching input driver".