set of white frames uploaded there
F/5.6 - from 100 to 25600 isos - LENR off.
https://filebin.net/w4w7wo1juux5n1sg

(filesize 360 mb)

Not sure I am must do the LENR On, it seems not triggering all the time (eg: it won't trigger for 5s and less than 400 isos, I am kinda lazy to do white frames of 30 seconds over 100 125 160 200 250 and 400 isos)

Thanks @esby. I've downloaded the files and will take a look.

Figuring out a new decoding algorithm is quite outside my field of expertise, so we must rely on the efforts of others to figure that out first...

I am trying with various attempts, but for now I keep failing.

Assuming
bpp = 16

That would mean that
pixperblock = 8

And that for 16 bytes,
for each of the 8th values, we get one byte + the other one shifted to the left by 8 (shl 8) in the array of 16 bytes.

But I am just getting garbage as output.

That should looks like:

                (...)
                if (RT_pana_info.bpp == 16) {
                    rowptr[col + 0] = bytes[0] + ((bytes[1] ) << 8);
                    rowptr[col + 1] = bytes[2] + ((bytes[3] ) << 8);
                    rowptr[col + 2] = bytes[4] + ((bytes[5] ) << 8);
                    rowptr[col + 3] = bytes[6] + ((bytes[7] ) << 8);
                    rowptr[col + 4] = bytes[8] + ((bytes[9] ) << 8);
                    rowptr[col + 5] = bytes[10] + ((bytes[11] ) << 8);
                    rowptr[col + 6] = bytes[12] + ((bytes[13] ) << 8);
                    rowptr[col + 7] = bytes[14] + ((bytes[15] ) << 8);
                }
                else
                if (RT_pana_info.bpp == 14) {
                (...)

As a workaround, people can use adobe dng decoder (which works under wine)

@esby, the image file you uploaded (P1000258.RW2) contains 34 831 360 bytes used for the RAW image data with 5792x4352 pixels. On average that's just a little more than 11 bits per pixel value, so there's obviously some form of compression assuming it should be decoded as 16 bit values. There's no pattern every 16 bytes like with the old types of .RW2 files, so it seems like they came up with some completely new compression scheme. (Instead it looks like they divided the image into two components encoded separately, but I'm no expert.) Shame on Panasonic for not releasing any information about the new format.

It's a huffman compression, some new tiff tags (0x0040 etc), contains the huffman tree, init values and more.
Seems to be called CF2 codec but I've not found any information on it.

It's a huffman compression, some new tiff tags (0x0040 etc), contains the huffman tree, init values and more. Seems to be called CF2 codec but I've not found any information on it.

Nice! Then it might not be so difficult to decode the image data after all if you just manage to decode the Huffman codes. The compression ratio is quite similar to what you get with the Lossless JPEG Huffman compression used in DNG.

Other random question, even if we use a dng step with Adobe dng_decoder, do we need to adjust the camconst.json file ?

Is there any progress on this? I'm a total noob on decoding images, but a quick google search gives instructions on how to decode huffman images.