Include IANA-registered media type in metadata response

[guoyunhe]

Possible bug

Is this a possible bug in a feature of sharp, unrelated to installation?

• Running npm install sharp completes without error.
• Running node -e "require('sharp')" completes without error.

If you cannot confirm both of these, please open an installation issue instead.

Are you using the latest version of sharp?

• I am using the latest version of sharp as reported by npm view sharp dist-tags.latest.

If you cannot confirm this, please upgrade to the latest version and try again before opening an issue.

If you are using another package which depends on a version of sharp that is not the latest, please open an issue against that package instead.

What is the output of running npx envinfo --binaries --system --npmPackages=sharp --npmGlobalPackages=sharp?

Does this problem relate to file caching?

The default behaviour of libvips is to cache input files, which can lead to EBUSY or EPERM errors on Windows.
Use sharp.cache(false) to switch this feature off.

• Adding sharp.cache(false) does not fix this problem.

Does this problem relate to images appearing to have been rotated by 90 degrees?

Images that contain EXIF Orientation metadata are not auto-oriented. By default, EXIF metadata is removed.

• To auto-orient pixel values use the parameter-less rotate() operation.

• To retain EXIF Orientation use keepExif().

• Using rotate() or keepExif() does not fix this problem.

What are the steps to reproduce?

• create a *.avif image sharp
• read *.avif metadata and check format
• format is heif

What is the expected behaviour?

format should be avif, which is more specific

Please provide a minimal, standalone code sample, without other dependencies, that demonstrates this problem

https://github.com/guoyunhe/sharp-avif-metadata

Please provide sample image(s) that help explain this problem

[lovell]

Hello, the output is correct; AVIF images use a container format of heif and a codec of av1. This applies also to HEIC images, which use the heif container and the hevc codec.

The docs have recently been updated (but not yet published) - see #4483 (comment)

[guoyunhe]

Hello, the output is correct; AVIF images use a container format of heif and a codec of av1. This applies also to HEIC images, which use the heif container and the hevc codec.

In theory, this is correct. But in most cases, this will bring extra pain for web developer. Considering Node.js is mostly used for web apps, having a short cut for AVIF does make sense.

• AVIF has its own file extension .avif
• AVIF has its own MIME type image/avif

It is the same idea that supports both .avif() and .heif() output methods. Because web developers use avif so much more than heif or heic.

[lovell]

I quite like the idea of providing an image's MIME type as part of the metadata as this would allow support for future things like image/avif-sequence (when animated AVIF is implemented upstream). Would this help with your scenario?

[guoyunhe]

Would be great if MIME type can be provided, which is more universal when you need to exchange info with other libraries and systems.

[lovell]

Excellent, thank you, I've tagged this as a future possible enhancement.