Added Jpeg-Xs support

[goorjn]

Added Jpeg-Xs (sub)descriptor support.

This requested SMPTE dictionaries to be updated with newer ones containing jpeg-xs data.

There is also a fix proposal for a reported header's size error: header's size should not include index bytes.

[rayden84]

First of all: thank you for your contribution.
However, there is a disagreement on how to calculate the HeaderbyteCount, please see here: #17. Do you have a documentation for your claim, that it should not include the IndexTableSegment?

For the JPEGXS descriptor: do you have a sample file, so that I can test your work?

Thank you!

[goorjn]

In SMPTE-377m, we have the following:

HeaderByteCount specifies the number of bytes used for the header metadata in this partition. This starts at
the first byte of the key of the primer pack and ends after any trailing KLV fill item which is included within this
HeaderByteCount (see figure 6). The values shall be zero if there is no header metadata in this partition.

This shows that HeaderByteCount should not include Index Bytes (and we have another field for IndexByteCount).

I also attach a short jpeg-xs file created using bmx library tools.

[rayden84]

Thank you for your contributions, I just merged them. Would you mind passing me a sample of jpg-xs encoded mxf file?

[goorjn]

jpeg-xs.zip
Here is a zipped mxf file, tell me if it works ;-)