feat(pdu,graphics): add RemoteFX Progressive codec primitives#1196
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Benoît Cortier (CBenoit) merged 2 commits intoDevolutions:masterfrom Apr 2, 2026
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Add wire-format types for RemoteFX Progressive Codec (MS-RDPRFX Progressive Extension) and the computational primitives required for progressive refinement: ironrdp-pdu: Progressive codec block types (SYNC, CONTEXT, REGION, TILE_SIMPLE, TILE_FIRST, TILE_UPGRADE, FRAME_BEGIN, FRAME_END), quantization values with band-level accessors, tile header parsing. ironrdp-graphics: Reduce-extrapolate discrete wavelet transform (DWT) for 64x64 tile decomposition into 10 subbands. SRL (Subband Reconstruction Layer) entropy codec for progressive coefficient transmission with zero-run encoding and sign-magnitude packing.
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Pull request overview
Adds foundational RemoteFX Progressive codec support across ironrdp-pdu (wire-format block/types + stream parsing) and ironrdp-graphics (reduce-extrapolate DWT + SRL entropy codec), as part of the multi-codec EGFX initiative (#1158 §4).
Changes:
- Introduce progressive RFX wire block types (SYNC/CONTEXT/REGION/TILE_* / FRAME_*) plus stream encode/decode helpers.
- Add reduce-extrapolate 3-level DWT implementation for 64×64 tiles and expose it via
ironrdp-graphics. - Add an SRL entropy codec module intended for progressive upgrade passes.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 8 comments.
Show a summary per file
| File | Description |
|---|---|
| crates/ironrdp-pdu/src/codecs/rfx/progressive.rs | New progressive wire types + region/tile parsing and stream (en/de)code helpers |
| crates/ironrdp-pdu/src/codecs/rfx/mod.rs | Exposes the new progressive module |
| crates/ironrdp-graphics/src/srl.rs | New SRL entropy codec implementation + unit tests |
| crates/ironrdp-graphics/src/lib.rs | Exposes new dwt_extrapolate and srl modules |
| crates/ironrdp-graphics/src/dwt_extrapolate.rs | New reduce-extrapolate DWT implementation + layout helpers/tests |
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SRL codec: fix encode/decode asymmetry for zero-run handling at k=0 and unary magnitude coding. Encoder now processes zero runs at all k values and recomputes k after each kp update to stay in sync with the decoder. Aligned magnitude coding to standard quotient/remainder scheme. Strengthened round-trip tests to check exact values including mixed zero/non-zero inputs. Progressive PDU: replace num_derive/num_traits with manual from_u16 match. Replace expect() panics with cast_length! in encode paths. Add numRects >= 1 and numQuant <= 7 guards, tile quant index bounds check, and fixed-size block blockLen validation per MS-RDPEGFX spec. Correct band index doc comment in dwt_extrapolate.
Greg Lamberson (glamberson)
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Apr 6, 2026
The merged progressive primitives PR (Devolutions#1196) added validation that a ProgressiveRegion must contain at least one rectangle. The test used an empty rects vec which now fails decoding.
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Part of the multi-codec EGFX implementation described in #1158 (Section 4).
Summary
Add wire-format types for RemoteFX Progressive Codec (MS-RDPRFX Progressive Extension) and the computational primitives required for progressive refinement.
ironrdp-pdu: Progressive codec block types (SYNC, CONTEXT, REGION, TILE_SIMPLE, TILE_FIRST, TILE_UPGRADE, FRAME_BEGIN, FRAME_END), quantization values with band-level accessors, tile header parsing.
ironrdp-graphics: Reduce-extrapolate discrete wavelet transform (DWT) for 64x64 tile decomposition into 10 subbands. SRL (Subband Reconstruction Layer) entropy codec for progressive coefficient transmission with zero-run encoding and sign-magnitude packing.
Changes
5 files, 2,326 lines. No changes to existing code.
Test plan