use arrayjoin and sequential about tifig

[streinhard]

Hi @jcupitt, thank you very very much for the tip! I implemented your suggestion in 59a7bd5 and it's indeed a lot faster. On my machine its saves around 160ms to build a full image. Awesome!

Switching to sequential access is also a great idea, however, by now we decode HEVC tiles directly to memory using libav. So gone are the tempfiles and unnecessary IO slow downs. ;)

Also many kudos for libvips in general! It's a very pleasant API to use and faster than lightning. Keep up the good work, it's appreciated!

[jcupitt]

That's great! I'm glad it helped.

Do you mean you are using new_from_memory now? If so, you're right, seq is not relevant. If you are still going via JPEG, then seq should give a speedup.

[streinhard]

Yup, we're using new_from_memory since that's another great way to speed up things 😉 . Thanks again!

[jcupitt]

Off-topic: there's talk of adding HEIF to libvips as a supported format. Would you be interested in getting your loader into core libvips? It shouldn't be a large amount of work.

[streinhard]

We like that idea ;). At the moment, we try to get tifig working for the cause we need it for: Creating thumbnails of HEIC images in a cloud solution. Once we get there, we sure would love to integrate our solution into vips. However, there's two things that probably need to be considered: Nokiatech's heif library is C++ only at the moment therefore doesn't really fit into vips ecosystem. The other point is HEVC decoding. We're relying on libav, which could be integrated, but is a huge monster itself.

[jcupitt]

libvips has a C API, but uses C++ internally, so I think that would be OK.

libav is indeed a huge monster :( A heifload operator would need to be optional, since it would probably be unacceptable for many users.