https://w3c.github.io/webcodecs/#dom-videoframe-videoframe-data-init should validate the plane layout according the coded width and height

[youennf]

https://w3c.github.io/webcodecs/#dom-videoframe-videoframe-data-init step 9 is computing the plane layout according parsedRect which is computed from visibleWidth/visibleHeight.
It seems codedWidth and codedHeight should be used instead, which would be consistent with checking whether the buffer is large enough.
See also https://bugs.webkit.org/show_bug.cgi?id=256848.

[youennf]

Switching to using codedWidth/codedHeight seems to align with what Chrome does AIUI: https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/webcodecs/video_frame.cc;l=849;drc=a3636d1ffd79769d79cb736dcf0066eeef408762

[sandersdan]

Agreed, combinedLayout is only used to run the check in step 11, which should be making sure that the buffer is large enough to contain the entire coded region of the frame. It's not necessary to compute anything related to the visible region here, but Compute Layout and Allocation Size algorithm is shared with copyTo() which does.

The complexity comes from having to support explicit and implicit layouts. The actual check just needs to ensure that the buffer contains the full planeCodedHeight * planeStride bytes for every plane.

It could be worth making this more obvious because using planeCodedWidth * planeSampleBytes for the last row instead of planeStride might be logical but would differ from the spec intention.