- [~] SIMD-first RGB-to-native-plane conversion now feeds eight-bit and high-bit-depth bordered AV1 source frames directly, preserving ImageSharp's arbitrary packed-pixel input contract without an intermediate full-frame native-plane copy.
- [~] Forward transform families, transform workspace, and an allocation-free DC intra block boundary exist locally. For eight-bit and high-bit-depth samples, the composed boundary now follows current libaom's encoder order: predict into the reconstruction plane, subtract prediction from source, transform, quantize into separate qcoeff and dqcoeff storage, retain EOB and transform type, and inverse-transform only when EOB is nonzero so later blocks consume decoder-identical references. Prediction and subtraction retain their SIMD-first operators, independent source and reconstruction strides are preserved, and no frame-sized or per-block buffer is introduced. One reusable 61 KiB allocator owner supplies tightly packed residual, aligned transform-coefficient, dequantized-coefficient, and transform scratch spans across transform blocks; quantized coefficients write directly to the retained frame coefficient owner instead of being duplicated. Stage-by-stage scalar-oracle, padding, retained-syntax, and zero-allocation coverage passes 6 of 6 through direct net11 VSTest in Release. Frame traversal still needs to select blocks, gather contiguous left references, and supply coefficient-owner slices.
- [~] Forward transform families, transform workspace, and an allocation-free DC intra block boundary exist locally. For eight-bit and high-bit-depth samples, the composed boundary now follows current libaom's encoder order: predict into the reconstruction plane, subtract prediction from source, transform, quantize into separate qcoeff and dqcoeff storage, retain EOB and transform type, and inverse-transform only when EOB is nonzero so later blocks consume decoder-identical references. Prediction and subtraction retain their SIMD-first operators, independent source and reconstruction strides are preserved, and no frame-sized or per-block buffer is introduced. The block boundary consumes the real bordered encoder-plane regions and indexes their one-segment owner directly; this preserves physical row strides without a row copy and avoids the per-call enumerator allocation exposed by the initial array-only test. One reusable 61 KiB allocator owner supplies tightly packed residual, aligned transform-coefficient, dequantized-coefficient, and transform scratch spans across transform blocks; quantized coefficients write directly to the retained frame coefficient owner instead of being duplicated. Stage-by-stage scalar-oracle, physical-border, retained-syntax, and zero-allocation coverage passes 6 of 6 through direct net11 VSTest in Release. Frame traversal still needs to select blocks, gather contiguous left references, and supply coefficient-owner slices.
- [~] Symbol writer, coefficient writer, and tile writer fragments exist locally.
- [~] A non-owning encoder-frame view now separates visible conversion regions from coded regions and performs complete left, top, right, bottom, and corner extension across each bordered plane. Current libaom uses 8-sample-aligned coded dimensions, a 32-sample-aligned luma stride with chroma stride derived from it, and a 64-pixel luma border for non-resized all-intra encoding. One operation-ready frame owner now rents the aligned Y, U, and V storage contiguously, exposes non-owning `Buffer2D` plane views, and returns the rent exactly once. A 4K 4:2:0 frame occupies about 13.0 MiB at 8-bit or 26.0 MiB at 10/12-bit; source and reconstruction therefore remain distinct frame owners rather than adding a full-frame copy. The corrected tests use this real ownership path and verify the exact 54 KiB 64x64 4:2:0 rent. The frame-encoder boundary converts packed pixels directly into the source owner before extension; the containing encode operation still needs to instantiate matching source and reconstruction owners with ordinary `using` lifetimes.
- [~] Temporal delimiter, sequence header, frame header, and combined-frame tile-group writing exist locally. The remaining required metadata, padding, and encoder-wide syntax paths are not complete.