- [~] Finalized transform coefficients and packed EOB/type state now use raster-ordered, per-superblock plane segments matching current libaom's coefficient-pool geometry. One ImageSharp allocator owner replaces libaom's separate coefficient, EOB, and entropy-context allocations while preserving the full 1024 luma and 256-per-chroma 4x4 state capacity of a 128x128 4:2:0 superblock; the forward transform and mode-decision stages still need to populate this owner.
- [~] Tile partition writing now follows current libaom's recursive `write_modes_sb` preorder traversal and `update_ext_partition_context` edge updates directly. The obsolete SVT-derived global geometry catalog and its unimplemented lookup are removed; transform geometry is derived in libaom's bounded 64x64 residual order, fixed intra transform-size symbols use the reference depth and neighbor contexts, frame-edge and segmentation syntax use mode-information units, and 128x128 CDEF units use libaom's 0-to-3 indexing and first-block strength ownership. Partition and mode analysis still need to populate these retained decisions; variable inter-transform syntax remains part of later inter-frame support.
- [~] The coefficient symbol encoder now reuses tile-lifetime level and context workspaces instead of allocating per transform. Its range coder matches current libaom's 64-bit coding window, bulk big-endian byte flush, and backward carry propagation while using one byte of allocator scratch per estimated output byte instead of the former 16-bit pre-carry storage. The reference-type symbol encoder is passed normally through tile traversal, and the operation boundary owns the allocator-backed item payload stream for exactly one synchronous encode. Every remaining encoder fragment must be audited before it becomes active.
- [~] The coefficient symbol encoder now reuses tile-lifetime level and context workspaces instead of allocating per transform, defers both coefficient rents until the first nonzero transform block, and disposes all tile scratch independently from the detached encoded bytes. Its range coder matches current libaom's 64-bit coding window, bulk big-endian byte flush, and backward carry propagation while using one byte of allocator scratch per estimated output byte instead of the former 16-bit pre-carry storage. The reference-type symbol encoder is passed normally through tile traversal, and the operation boundary owns the allocator-backed item payload stream for exactly one synchronous encode. Every remaining encoder fragment must be audited before it becomes active.
- [~] The planar conversion, forward transform, and forward quantizer use descending SIMD dispatch: Vector512, Vector256, Vector128, then scalar. Apply the same rule to every later hot-path family.
- [~] Forward-quantizer FeatureTestRunner and zero-allocation tests compare every hardware tier with an independent scan-order scalar oracle shaped from current-main libaom. Both passed direct net11 VSTest in Release.
- [~] The combined-frame writer now completes the byte-counted uncompressed frame header before starting the optional multi-tile tile-group flag, matching current libaom's separate frame-header and tile-group writers. A non-uniform two-tile round trip verifies the explicit boundaries, both tile payloads, and complete stream consumption through direct net11 VSTest in Release.
James Jackson-South
1 month ago