Why is encoding speed irrelevant?
I'm currently in the process of scanning and archiving lots of photographs as high-resolution 16-bit PNG's and encoding speed is definitely a significant influence on how long this process takes.
I'm currently in the process of scanning and archiving lots of photographs as high-resolution 16-bit PNG's and encoding speed is definitely a significant influence on how long this process takes.
The vast majority of use-cases and users barely care about encoding performance. Your use is in the tiny minority. That isn't to say that you don't have a use-case, just that because of how rarely encoding speed matters, it truly is "almost irrelevant" for 99.99% of users 99.99% of the time.
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It definitely would be nice if JPEG-XL also had good encoding performance, though. There's an experimental fast encoder in development currently[1], although before that lands, it would be nice if your scanning tool supported a workflow somewhat like "scan in parallel with image encoding, present encoded images to user, and allow them to asynchronously go back and re-scan/encode/review pages that came out badly".
[1] https://github.com/libjxl/libjxl/tree/main/experimental/fast...
If you're doing this at such a scale that encoding speed matters (like if you're Instagram) the major concern would likely be cost, which you're going to save in bandwidth every time an image is viewed.
How am I going to "throw more CPU power at the problem" when I'm using a scanner hooked up to my laptop? Should I buy myself a new, more powerful laptop? That doesn't sound cheap.
As for "just" waiting... my time is valuable, and I have better things to do with it than wait... and, unfortunately, the process of scanning and encoding needs a lot of babysitting from me, so I can't just dump a bunch of photos in my scanner and come back when it's all over if I want even half-decent results, not to mention archival quality images.
In this real-world scenario, a quicker encoding speed would save me a lot of valuable time, and there's no getting around it short of hiring a skilled and trusted person to do it for me.
The use of intermediate formats is a well proven technique in video editing where encoding real time to AVC/HEVC at high quality is not possible. Codecs like ProRes are used that are much easier to encode to at the expense of storage space.
For context I started a neg scanning project a few years ago, ~150 rolls on an epson v850 (flatbed), and stuck with the default compressed tif after some surface research. There is little chance I would consider another processing step .. unless it was batched on a server somewhere! Very painstaking process, which has been on indefinite hold for a small while now (waiting for the AI to catch up).