Compressed image transport plugin uses which jpeg encoding library?

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Hello Some time ago, I remember /compressedimage topic was consuming 700KB/s bandwidth for 640*480 image @ 30 fps at 80% quality.

After that, I think I started learning gstreamer and I re-install libjpeg-dev or libjpeg-turbo8 or something I did.

Now when I resume working on /compressedimage topic, I am realizing that it is consuming 1.2MB/s bandwidth for same 640*480 @ 30fps at 80% quality.

Which jpeg library does compressed image transport plugin use?

I am wishing to have lowest bandwidth possible for 80% jpeg quality.