Questions about Eiger2

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Folks,

I have a couple of questions about the Eiger2 that I'm hoping someone can help me with:

#1

I am working on the EPICS driver for the Eiger2 with the Stream2 interface.  I have it working fine with Compression=None and Compression=bslz4.  However, I am having trouble with compression=lz4.  It appears to me that the lz4 compression with Stream2 is different from the lz4 compression with Stream.

 

These are the compressed sizes I see for a radioactive source and 10 second count time.

 

Interface	Compression	Compressed data size
Stream	bslz4	248 KB
Stream2	bslz4	248 KB
Stream	lz4	771 KB
Stream2	lz4	1,119 KB

 

The data size for bslz4 is the same for Stream and Stream2, and I can decompress using the same code.

 

However, the data size with lz4 is significantly larger with Stream2 than with Stream.  More importantly when I try to decompress the lz4 data from Stream2 using the same code I use for Stream it crashes.

 

Has the lz4 compression in Stream2 changed from Stream, and is this documented somewhere?

 

#2

When I enable threshold2 I expect that the HDF5 file written by the Dectris server should contain 2 images, one for threshold1 and one for threshold2.  However, the file size with threshold2 enabled is the same as when it is disabled.  In both cases h5dump –header shows the following for the data:

 

         DATASET "data" {

            DATATYPE  H5T_STD_U32LE

            DATASPACE  SIMPLE { ( 1, 1062, 1028 ) / ( H5S_UNLIMITED, 1062, 1028 ) }

            ATTRIBUTE "image_nr_high" {

               DATATYPE  H5T_STD_U64LE

               DATASPACE  SCALAR

            }

            ATTRIBUTE "image_nr_low" {

               DATATYPE  H5T_STD_U64LE

               DATASPACE  SCALAR

            }

         }

 

What am I misunderstanding?

Thanks,

Mark