{"abstract":"Per-channel predictor update overwrites only the first state lane.","category":"PCM sample encoding","checks":8,"contract":"Encode frame-major PCM residuals with independent per-channel amplitude predictors and frame-index resets; preserve residual frame shape.","contract_signature":"frames, seeds, resets","evaluation_group":"s3-pcm-pcm-channel-predictor","failed_approach":"Feeding residual instead of amplitude corrupts later frames.","family":"s3-pcm-pcm-channel-predictor-feedback-channel","id":"FA-49346","implementations":{"attempt":{"sha256":"55d2e1144632f911b719c91dfa523cb3f8b03f3baec6cd37f482d47b89a35015","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(frames, seeds, resets):\n    state=list(seeds)\n    out=[]\n    for index,frame in enumerate(frames):\n        if index in resets:\n            state=list(seeds)\n        residual=[]\n        for channel,sample in enumerate(frame):\n            residual.append(sample-state[channel])\n            state[channel]=sample-state[channel]\n        out.append(residual)\n    return [out,state]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([[5, 10], [7, 9]], [2, 8], [])), [[[3, 2], [2, -1]], [7, 9]])\ncheck('oracle 2', solve(*([[2, 4], [3, 8], [7, 9]], [1, 2], [1])), [[[1, 2], [2, 6], [4, 1]], [7, 9]])\ncheck('oracle 3', solve(*([], [3, 4], [])), [[], [3, 4]])\ncheck('oracle 4', solve(*([[1], [3], [2]], [0], [2])), [[[1], [2], [2]], [2]])\ncheck('oracle 5', solve(*([[-2, 3], [0, 1]], [-1, 4], [])), [[[-1, -1], [2, -2]], [0, 1]])\ncheck('oracle 6', solve(*([[1, 2, 3]], [3, 2, 1], [0])), [[[-2, 0, 2]], [1, 2, 3]])\ncheck('oracle 7', solve(*([[0, 0], [0, 0]], [1, -1], [])), [[[-1, 1], [0, 0]], [0, 0]])\nif N == 1: check('variant packet 1', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 2: check('variant packet 2', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 3: check('variant packet 3', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 4: check('variant packet 4', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 5: check('variant packet 5', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"1af4740330fc18156a4349aa371c9953b3bde880031db0f9099e7a5a3a7094fc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(frames, seeds, resets):\n    state=list(seeds)\n    out=[]\n    for index,frame in enumerate(frames):\n        if index in resets:\n            state=list(seeds)\n        residual=[]\n        for channel,sample in enumerate(frame):\n            residual.append(sample-state[channel])\n            state[0]=sample\n        out.append(residual)\n    return [out,state]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([[5, 10], [7, 9]], [2, 8], [])), [[[3, 2], [2, -1]], [7, 9]])\ncheck('oracle 2', solve(*([[2, 4], [3, 8], [7, 9]], [1, 2], [1])), [[[1, 2], [2, 6], [4, 1]], [7, 9]])\ncheck('oracle 3', solve(*([], [3, 4], [])), [[], [3, 4]])\ncheck('oracle 4', solve(*([[1], [3], [2]], [0], [2])), [[[1], [2], [2]], [2]])\ncheck('oracle 5', solve(*([[-2, 3], [0, 1]], [-1, 4], [])), [[[-1, -1], [2, -2]], [0, 1]])\ncheck('oracle 6', solve(*([[1, 2, 3]], [3, 2, 1], [0])), [[[-2, 0, 2]], [1, 2, 3]])\ncheck('oracle 7', solve(*([[0, 0], [0, 0]], [1, -1], [])), [[[-1, 1], [0, 0]], [0, 0]])\nif N == 1: check('variant packet 1', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 2: check('variant packet 2', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 3: check('variant packet 3', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 4: check('variant packet 4', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nif N == 5: check('variant packet 5', solve(*[[[5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9], [5, 10], [7, 9]], [2, 8], []]), [[[3, 2], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1], [-2, 1], [2, -1]], [7, 9]])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Stipulated finite model; no claim of hardware timing or full file-format conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"s3-pcm-pcm-channel-predictor-feedback-channel","generated_at":"2026-09-29T14:44:59.248240+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline PCM interchange uses these exact bounded packet and sample representation decisions.","root_cause":"Per-channel predictor update overwrites only the first state lane.","sha256":"309d0ec0a1fe3253a1cbc17b860ed66d97f0dbf2f142ab0c33cfc804e20af57c","title":"Pcm channel predictor: feedback channel · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.844,"exit_code":1,"observations":[{"actual":[[[3,2],[4,7]],[4,7]],"check":"oracle 1","expected":[[[3,2],[2,-1]],[7,9]],"passed":false},{"actual":[[[1,2],[2,6],[5,3]],[5,3]],"check":"oracle 2","expected":[[[1,2],[2,6],[4,1]],[7,9]],"passed":false},{"actual":[[],[3,4]],"check":"oracle 3","expected":[[],[3,4]],"passed":true},{"actual":[[[1],[2],[2]],[2]],"check":"oracle 4","expected":[[[1],[2],[2]],[2]],"passed":true},{"actual":[[[-1,-1],[1,2]],[1,2]],"check":"oracle 5","expected":[[[-1,-1],[2,-2]],[0,1]],"passed":false},{"actual":[[[-2,0,2]],[-2,0,2]],"check":"oracle 6","expected":[[[-2,0,2]],[1,2,3]],"passed":false},{"actual":[[[-1,1],[1,-1]],[1,-1]],"check":"oracle 7","expected":[[[-1,1],[0,0]],[0,0]],"passed":false},{"actual":[[[3,2],[4,7],[1,3],[6,6]],[6,6]],"check":"variant packet 1","expected":[[[3,2],[2,-1],[-2,1],[2,-1]],[7,9]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[[3, 2], [4, 7]], [4, 7]], \"expected\": [[[3, 2], [2, -1]], [7, 9]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[[1, 2], [2, 6], [5, 3]], [5, 3]], \"expected\": [[[1, 2], [2, 6], [4, 1]], [7, 9]], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [[], [3, 4]], \"expected\": [[], [3, 4]], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [[[1], [2], [2]], [2]], \"expected\": [[[1], [2], [2]], [2]], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[[-1, -1], [1, 2]], [1, 2]], \"expected\": [[[-1, -1], [2, -2]], [0, 1]], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[[-2, 0, 2]], [-2, 0, 2]], \"expected\": [[[-2, 0, 2]], [1, 2, 3]], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [[[-1, 1], [1, -1]], [1, -1]], \"expected\": [[[-1, 1], [0, 0]], [0, 0]], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [[[3, 2], [4, 7], [1, 3], [6, 6]], [6, 6]], \"expected\": [[[3, 2], [2, -1], [-2, 1], [2, -1]], [7, 9]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.002,"exit_code":1,"observations":[{"actual":[[[3,2],[-3,1]],[9,8]],"check":"oracle 1","expected":[[[3,2],[2,-1]],[7,9]],"passed":false},{"actual":[[[1,2],[2,6],[-1,7]],[9,2]],"check":"oracle 2","expected":[[[1,2],[2,6],[4,1]],[7,9]],"passed":false},{"actual":[[],[3,4]],"check":"oracle 3","expected":[[],[3,4]],"passed":true},{"actual":[[[1],[2],[2]],[2]],"check":"oracle 4","expected":[[[1],[2],[2]],[2]],"passed":true},{"actual":[[[-1,-1],[-3,-3]],[1,4]],"check":"oracle 5","expected":[[[-1,-1],[2,-2]],[0,1]],"passed":false},{"actual":[[[-2,0,2]],[3,2,1]],"check":"oracle 6","expected":[[[-2,0,2]],[1,2,3]],"passed":false},{"actual":[[[-1,1],[0,1]],[0,-1]],"check":"oracle 7","expected":[[[-1,1],[0,0]],[0,0]],"passed":false},{"actual":[[[3,2],[-3,1],[-4,2],[-3,1]],[9,8]],"check":"variant packet 1","expected":[[[3,2],[2,-1],[-2,1],[2,-1]],[7,9]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[[3, 2], [-3, 1]], [9, 8]], \"expected\": [[[3, 2], [2, -1]], [7, 9]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[[1, 2], [2, 6], [-1, 7]], [9, 2]], \"expected\": [[[1, 2], [2, 6], [4, 1]], [7, 9]], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [[], [3, 4]], \"expected\": [[], [3, 4]], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [[[1], [2], [2]], [2]], \"expected\": [[[1], [2], [2]], [2]], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[[-1, -1], [-3, -3]], [1, 4]], \"expected\": [[[-1, -1], [2, -2]], [0, 1]], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[[-2, 0, 2]], [3, 2, 1]], \"expected\": [[[-2, 0, 2]], [1, 2, 3]], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [[[-1, 1], [0, 1]], [0, -1]], \"expected\": [[[-1, 1], [0, 0]], [0, 0]], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [[[3, 2], [-3, 1], [-4, 2], [-3, 1]], [9, 8]], \"expected\": [[[3, 2], [2, -1], [-2, 1], [2, -1]], [7, 9]], \"passed\": false}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}