NV12 format, number of bytes should be 1.5x of pixel count, instead of 2

[chengguizi]

Describe the bug

I am seeing error like this when attempting to us NV12 format

Rerun ERROR: Image buffer has the wrong size. Got 3072000 bytes, expected 4096000

rerun/rerun_cpp/src/rerun/image_utils.hpp

Line 168 in 9f16f45

case datatypes::PixelFormat::NV12:

https://ref.rerun.io/docs/cpp/stable/namespacererun_1_1datatypes.html

Upon checking I suspect the image_utils.hpp wrongly code NV12 as 4:2:2 type, where it should be 4:2:0 type which is consistent in docs and rest of Internet.

[Wumpf]

Seems the mistake creeped into both the C++ and Rust SDKs

• https://github.com/rerun-io/rerun/blob/cb652ab2c0743c607eafa1beaa1d3dee44eef514/rerun_cpp/src/rerun/image_utils.hpp

• rerun/crates/store/re_types/src/datatypes/pixel_format_ext.rs

  Line 49 in cb652ab

  Self::Y_U_V16_FullRange | Self::Y_U_V16_LimitedRange | Self::NV12 => {

.. while being correctly documented in various places (e.g.

rerun/crates/store/re_types/src/datatypes/pixel_format.rs

Line 45 in cb652ab

/// `NV12` (aka `Y_UV12`) is a YUV 4:2:0 chroma downsampled form at with 12 bits per pixel and 8 bits per channel.

)

Should be trivial to fix!

There's a semi-manual test for verifying that python ingest & viewer decode works but that ends up not hitting any of the broken paths :/

rerun/tests/python/release_checklist/check_chroma_subsampling.py

Line 79 in cb652ab

def bgra2nv12(bgra: npt.NDArray[np.uint8]) -> npt.NDArray[np.uint8]: