Add 21 JXL files exposing libjxl/jxl-rs LZ77 distance-cluster bug#5
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Add 21 JXL files exposing libjxl/jxl-rs LZ77 distance-cluster bug#5lilith wants to merge 1 commit into
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Three VarDCT bitstreams chosen to cover the distinct error variants the bug manifests as. All from the same root cause (LZ77 distance cluster shifted away from context_map.last() by AC-context padding) but each fails at a different validation point in the AC reader. libjxl djxl 0.12.0 and jxl-oxide 0.12.5 decode all three cleanly. libjxl/jxl-rs v0.4.3 rejects them; fix in libjxl/jxl-rs#766. | file | size | manifests as | | akfcrc022_e9_d3.0.jxl | 22 KB | Invalid AC: 8 nonzeros after decoding block | | gb82-sc_windows9_d0.25.jxl | 51 KB | Invalid AC: nonzeros 144 is too large for 1 8x8 blocks | | gb82-sc_terminal_d0.5.jxl | 58 KB | ANS stream checksum mismatch | Encoder: imazen/jxl-encoder at e9 + low distance on screen content (uses Optimal/Greedy LZ77 — libjxl never emits these for VarDCT, so its existing test corpora can't catch the bug). References regenerate via jxl/generate_references.sh. Refs: - libjxl/jxl-rs#765 (bug) - libjxl/jxl-rs#766 (fix) - imazen/zenjxl-decoder#15 (downstream tracking + regression test) - imazen/jxl-encoder#29 (encoder default rationale)
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Cleanup of the issue-15 branch before merge to main: - Replace the corpus-walking regression test with a single in-tree file test pinned to the smallest reproducer (akfcrc022_e9_d3.0.jxl, 22 KB). The full historical corpus (3 distinct-variant files) lives in imazen/codec-corpus PR #5 under jxl/conformance/ and is exercised by the existing codec_corpus parity tests when the corpus is reachable. - Remove hard-coded /mnt/v/fuzzes/... path. Path now resolves via CARGO_MANIFEST_DIR -- CI-portable, no external setup required. - Drop benchmark TSVs and the issue-15 sweep summary md from this branch; they were investigation scratch and the conclusions are captured in the upstream PR + tracking issues. Test fingerprints the bug: decode succeeds, output is 512x512x{3,4}u8. Pixel parity is verified by the codec_corpus tests against the codec-corpus reference outputs once that PR merges. Refs: - libjxl/jxl-rs#765 (bug) - libjxl/jxl-rs#766 (fix) - imazen/codec-corpus#5 (full corpus)
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21 VarDCT bitstreams that exercise the Optimal/Greedy LZ77 path. Produced by imazen/jxl-encoder at e9 + low distance on screen content.
libjxl djxl 0.12.0 and jxl-oxide 0.12.5 decode all 21 cleanly.
libjxl/jxl-rs v0.4.3 rejects all 21 with
Invalid AC: N nonzeros after decoding blockdue to a context-map padding bug (root cause + fix in libjxl/jxl-rs#766).libjxl's encoder pins LZ77 to
kRLEfor VarDCT at every effort tier (lib/jxl/enc_ans_params.h+lib/jxl/enc_frame.cc:1259-1263), so existing libjxl test corpora don't exercise this code path. Adding these to conformance ensures any future regression inOptimal/GreedyLZ77 + VarDCT decoding is caught.Files (21 total)
akfcrc022_e9_d{1.5,2.0,3.0}.jxl— 3 files, 22-29 KB. The 22 KBd3.0variant is the smallest reproducer.gb82-sc_{terminal,gui,codec_wi,gmessage,graph,imac_dar,windows,windows9}_d{0.25,0.5,1.0,1.5,2.0}.jxl— 18 files, 32-447 KB. Screen-content variants at varying distances.References regenerate via
jxl/generate_references.shagainstdjxl 0.12.0.Refs