trouble with write_texture data

[ford442]

I have been trying to work around the lack of HTMLVideoElement interaction by getting video frame data into a canvas element and then into C++ webgpu.h write_texture via emscripten FS files. Using regular webgl getImageData commands gives me an odd shaped image over in C++. Maybe i don't know the exact request of bytesPerBlockRow or blockRowsPerImage purpose or equation? I get my frames all chopped up into consecutively smaller chunks as if the data sizes don't line up.

Anyone want to clarify?
ty...