alistair7

This is working since 0d89f89, but it hasn't made it into a release yet. Prior to that change, cjxl(_ng) didn't add metadata to the JXL output. I believe the library...

I was reluctant to rely on `jxlinfo | grep` too, so I wrote a minimal Python script for detecting reconstructable JPEGs by parsing the JXL container and looking for a...

> if head -c 64 test.jxl | grep -qa "jbrd"; then ... That's definitely easier! But bear in mind the `jbrd` doesn't have to be in the first 64 bytes...

The fix for #2463 has solved my issue here (albeit at the cost of 33% of the reference frame slots :sweat_smile:). This can be closed unless you want to keep...

According to `jpegtran`... ``` $ jpegtran -copy all 20240915_144212.jpg > 20240915_144212_copy.jpg Invalid SOS parameters for sequential JPEG ``` I don't know what that means, but whatever it is, jpegtran fixes...

> If you specified "--allow_jpeg_reconstruction 0" then cjxl will convert the already lossy JPG to JXL in a lossy manner. The resulting JXL will therfore not be the same as...

Yes, if you have access to `jpegtran` from libjpeg-turbo you could try: `jpegtran -copy all -optimize 0_0009.jpg > 0_0009_copy.jpg` That keeps pixels and metadata exactly the same, but rewrites the...

From what I understand, the JXL format doesn't support lossless transcoding of ["unusual"](https://github.com/libjxl/libjxl/issues/895#issuecomment-991148244) JPGs, and it's a limitation in the JXL spec, not something that can be fixed in libjxl....

cjxl [reads text chunks](https://github.com/libjxl/libjxl/blob/29eb988ed6f4fdd2279a27d2519a3e00d0651cbd/lib/extras/dec/apng.cc#L246) containing raw Exif / XMP data, which it encodes as `Exif` / `xml ` boxes, and ignores any others, so it can certainly see them. Rightly...

You might get a more useful error code by calling `JxlEncoderGetError` after the error, but the exact error message will only appear if libjxl was built in debug mode.