Snapshot quality is blocky

[kiokushitaka]

I finally found some tutorials on how to get VLC to automatically make a snapshot every few frames, and everything works fine-- the images appear in the folder I've designated, in sequential order, and are taken at the ratio I specified. The problem is that, for some reason, there are these blocks that appear, but if I watch the video with the auto snapshot turned off, these artifacts aren't there.

Video is also perfectly fine in other media players (MPC, for example).

On my old computer, I vaguely recall fixing this issue, but I can't remember how I did it or what even caused it. Can someone help me?

I'm using VLC 2.0.5. Twoflower.

***I should add that this only happens when using the automatic snapshot settings, not if I manually take snapshots while watching the file.

[Jean-Baptiste Kempf]

Reduce the frequency of snapshots?

[kiokushitaka]

I had planned to take the snapshots in order to make animated GIFs, but even when I reduce the number of snapshots per second, they still come out funny. With older versions of VLC there was a way to make it read large files (these are all Blu-ray HD) with less errors... I don't remember what I did exactly, but I vaguely recall inputting a large number, perhaps 3000 or something around that. Frame rate? I'm not sure...