initial work on generic compression decoding

strukturag / libheif

libheif is an HEIF and AVIF file format decoder and encoder.

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initial work on generic compression decoding #1194

Closed bradh closed 2 days ago

bradh commented 5 days ago

This is from the draft Amendment 2 for ISO/IEC 23001-17.

It re-uses and generalises the existing zlib support (from header compression), and adds an optional dependency on Brotli.

It also picks up a few extra Go and JS error codes that I noted when adding mine. Those could be a separate commit if preferred.

Feedback on the approach and internal API changes would be appreciated.

I still have some work to do on this:

[ ] decode row compression
[ ] decode pixel compression (needs test data)
[ ] icbr byte ranges (needs test data)
[ ] some unit tests

There is no encoding support for this yet, and we'd likely need some kind of configuration option to specify that. It seems a bit premature given where the draft is up to.

Jamaika1 commented 2 days ago

Only applies to png and jpg file decoder. Tiff isn't taken into account.

bradh commented 2 days ago

Only applies to png and jpg file decoder. Tiff isn't taken into account.

I think I have no idea what you are referring to. This is intended to decode zlib/deflate/brotli compressed HEIF. What are you expecting to happen?

Jamaika1 commented 2 days ago

It's true. I don't know everything. zlib and deflate was previously added for png. Brotli? I guess only jpegxl uses brotli. libtiff I see that the entire file can be added to libheif. It has lot of compression algorithms. (lerc,zstd,webp,libdeflate). I don't know what it's tested on.

bradh commented 2 days ago

It's true. I don't know everything. zlib and deflate was previously added for png. Brotli? I guess only jpegxl uses brotli. libtiff I see that the entire file can be added to libheif. It has lot of compression algorithms. (lerc,zstd,webp,libdeflate). I don't know what it's tested on.

I think you're confused. We have the uncompressed codec in HEIF. That is defined in ISO/IEC 23001-17:2024.

There is an upcoming amendment to ISO/IEC 23001-17:2024 to allow (lossless) compression with zlib, deflate and brotli, intended for formats like floating point and signed integer, or high bit depth. So similar to what TIFF does.

silverbacknet commented 2 days ago

Only applies to png and jpg file decoder. Tiff isn't taken into account.

FWIW, a separate libtiff decoder was also submitted today, that seems to be exactly what you were looking for: #1205 It's a limited proof of concept that could be extended in the future, but it works for your basic 8-bit grey and 24/32-bit rgb/a color images for now, in any format libtiff can decode. I assume it'll be a few more iterations before it's merged into the mainline.

bradh commented 2 days ago

Reworked and targets master on #1208