1654462 - AVIF files should support alpha/transparency

Status: RESOLVED FIXED

(Core :: Graphics: ImageLib, defect, P1)

Description

[Thomas Daede [:TD-Linux]]

Attachment: dst_lossless.avif

The attached AVIF should be transparent in the same places as the attached PNG.

Comment 1

[Thomas Daede [:TD-Linux]]

Attachment: src.png

Comment 2

[C.M.Chang[:chunmin]]

To-do tasks for prototype:

• [x] Expose alpha_item and premultiplied_alpha
  • mp4parse-rust draft here
  • gecko patch here
  • manual for vendoring mp4parse-rust
• [x] Decode alpha plane with Dav1d (draft here)
• [x] Decode alpha plane with AOM
  • We plan to delete the AOM decoder in the future so no worry to implement this.
• [x] Decode the primary item with the alpha item
  • Decode relies on gfx::ConvertYCbCrAToARGB , which is a wrapper calling libyuv
  • But it only works if the image format is I420. It's just a wrapper calling libyuv::I420AlphaToARGB
  • For other formats, the plan is to convert the YCbCr to ARGB first then inject the alpha data manually. (draft here)
• [ ] Create/Update test page
  • [x] for I420 layout: https://jsfiddle.net/2q5excm4/
  • [x] for I444 layout: https://jsfiddle.net/f13p2dLu/
  • [ ] Test for I422 layout

Comment 3

[C.M.Chang[:chunmin]]

Attachment: Bug 1654462 - Import mp4parse c api to get alpha item

This imports the change of https://github.com/mozilla/mp4parse-rust/pull/258

Once the above PR is merged in the upstream, it will be landed in the
gecko in a different bug maybe.

Comment 4

[C.M.Chang[:chunmin]]

Attachment: Bug 1654462 - Add alpha support in nsAVIFDecoder

This patch implements the transparency support for AVIF image files, if
the decoder preference is Dav1d. We have a plan to drop AOM decoder in
the future so this patch doesn't implement the alpha support for AOM
decoder. An side-benefit is that we can flip the decoder preference to
see the images before and after blending the alpha data.

This patch creates a function to convert the decoded YCbCr and Alpha
data to RGBA by using the existing ConvertYCbCrToRGB function to convert
the YCbCr data into RGB data first and then insert the Alpha data to the
RGBA buffer, if the layout of the decode YCbCr data is not I420. If the
layout is I420, the YCbCr and Alpha data can be converted by using the
libyuv::I420AlphaToARGB directly. (To see the image that calls the
ConvertYCbCrToRGB only, you can set the decoder to AOM.)

On the other hand, this patch refactors the nsAVIFDecoder a bit to make
the lifetime of the parsed data and decoded image data clearer. They
won't live longer than Parser object and {Dav1d, AOM}Decoder object.
This should improve the code readability.

Depends on D98950

Comment 5

[Phabricator Automation]

Comment on attachment 9191691 [details]
Bug 1654462 - Import mp4parse c api to get alpha item

Revision D98950 was moved to bug 1681811. Setting attachment 9191691 [details] to obsolete.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c1478d03a451
Add alpha support in nsAVIFDecoder r=jbauman

Comment 7

[Cristina Coroiu [:ccoroiu]]

https://hg.mozilla.org/mozilla-central/rev/c1478d03a451