Standalone quasi-random sampling. about ffcv

[GuillaumeLeclerc]

I don't think that would be possible as we use the file format itself to enable good performance with QUASI_RANDOM. Each dataset file is cut into pages/blocks (default 8MB) and generates an random order that makes sure that we only ever need BATCH_SIZE pages in RAM at any time. Moreover we use the fact that we know ahead of time in which order we will need this pages to pre-load them and compensate for slow disk io.
Unfortunately I don't see how we could make this possible without assuming the structure of the dataset file. What you suggest is a very different strategy. I suggest that you look into webdataset's implementation of shuffle. It seems that it's closer to what you want and also should work without converting your dataset.