-sample 1x1 and default quality

[ccxvii]

The docs say default quality is 75.

When using stock cjpeg, both these commands result in identical output:

cjpeg -sample 1x1
cjpeg -sample 1x1 -q 75

However, with mozjpeg these two commands result in very different output.
What exactly is going on here?

[kornelski]

It ends up using different quantization tables, due to the fact that the libjpeg API is stateful and the cjpeg tool is a kludge.

[FredWahl]

My problem is that I seem to get quality equal to 75 even if I used -quality 80. I don’t know if it matters if -sample 1x1 should come before or after -quality. My own code said quality was 65 rather then the 75 I got from an online tool which makes me wonder if there’s any tool that could return the estimated quality which I can use in my code