In terms of whether the ‘clean room’ approach is as critical in Europe or not, I can’t be sure. It might be more permissable for someone to use a decompile as a reference and also directly work on a replacement. However I’m pretty sure starting with a decompile of proprietary software as a direct codebase would run afoul of issues.
Otherwise, imagine you have an HEVC encoded rip of a 4K blu ray. You transcode it to AV1. The bytes are totally different, and even the resultant frames are likely not even pixel for pixel identical. I don’t think copyright law would deem that not a violation, regardless of jurisdiction.
In terms of whether the ‘clean room’ approach is as critical in Europe or not, I can’t be sure. It might be more permissable for someone to use a decompile as a reference and also directly work on a replacement. However I’m pretty sure starting with a decompile of proprietary software as a direct codebase would run afoul of issues.
Otherwise, imagine you have an HEVC encoded rip of a 4K blu ray. You transcode it to AV1. The bytes are totally different, and even the resultant frames are likely not even pixel for pixel identical. I don’t think copyright law would deem that not a violation, regardless of jurisdiction.