Files
scene-actor-extraction/src/nodes/identity_matcher_node.hpp
T
dtourolleandClaude Opus 5 9fc2763096 feat: expansion promotion gated on all three discontinuity signals
AR-019 — promotion may only borrow same-identity evidence from a span where
identity is certain, so every discontinuity signal now clears the buffers rather
than just the histogram cut.

is_scene_boundary was already named in the gate but never set by anything, so
that half of it was dead until AR-010 gave it a producer. It now does what the
spec always said. The third signal, an identity contradiction, needs no code
here: AR-015 closes a track whose belief swapped, so it can no longer promote.

Ownership now comes from the registry rather than a second tally. TrackGallery
was computing its own plurality vote over accepted frames, which meant two
different answers to "who is this track" could coexist in one run — and the
expansion one ignored the Bayesian accumulation entirely, weighting thirty
near-identical looks the same as thirty distinct ones. The local tally survives
only as a fallback for callers with no registry attached, which is the unit
tests and the replay harness.

Suite: 92 cases, 6133 assertions.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TRACES: AR-019, AR-010, AR-015 | SR-005
2026-07-31 15:11:56 +02:00

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#pragma once
#include "types.hpp"
#include "config.hpp"
#include "inference/similarity.hpp"
#include "gallery/gallery_store.hpp"
#include "gallery/gallery_calibration.hpp"
#include "gallery/track_gallery.hpp"
#include "track_registry.hpp"
#include <cstdint>
#include <cstring>
#include <iostream>
#include <limits>
#include <memory>
#include <stdexcept>
#include <vector>
// ── IdentityMatcherFunc ───────────────────────────────────────────────────────
// KPN node: compares each embedding against every reference embedding in the
// actor gallery using cosine similarity.
//
// Matching strategy — two modes selected at construction time:
//
// Calibrated (preferred): gallery calibration fits a sigmoid
// P(match) = σ(a·similarity + b) from intra/inter-class pairs.
// A face is accepted if P(match | best_actor) > prob_threshold.
//
// Fallback (no calibration): dual-criterion accept —
// (a) best cosine distance < match_threshold, OR
// (b) ratio test: best_dist/second_best_dist < match_ratio
// AND best_dist < match_ratio_ceil.
//
// In both modes, per-actor best similarity is determined by scanning
// reference embeddings and taking the closest (best-of-N).
//
// Gallery scan: the full reference set (tens of thousands of 512-dim
// embeddings) is uploaded to the GPU once at construction time and stays
// resident there. Per frame, only the small query matrix (n_faces x 512) is
// uploaded and a single SGEMM computes the full similarity matrix in well under
// a millisecond. The GPU math backend (cuBLAS or rocBLAS) lives behind
// ISimilarityEngine (backends/gemm_backend.cpp) and is selected at compile time.
struct IdentityMatcherFunc {
static constexpr std::string_view label() { return "identity_matcher"; }
// Max faces handled per frame without reallocating GPU buffers.
static constexpr int kMaxFaces = 32;
IdentityMatcherFunc(const ActorGallery& gallery, const Config& cfg)
: gallery_(gallery)
, prob_threshold_(cfg.prob_threshold)
, log_prior_odds_(std::log(cfg.match_prior / (1.f - cfg.match_prior)))
, threshold_(cfg.match_threshold)
, ratio_(cfg.match_ratio)
, ratio_ceil_(cfg.match_ratio_ceil)
, track_gallery_(cfg)
{
std::cerr << "[identity_matcher] flattening gallery embeddings...\n";
for (int ai = 0; ai < static_cast<int>(gallery_.actors.size()); ++ai) {
for (const auto& emb : gallery_.actors[ai].embeddings) {
flat_emb_.push_back(emb);
flat_actor_.push_back(ai);
}
}
n_gallery_ = static_cast<int>(flat_emb_.size());
std::cerr << "[identity_matcher] starting calibration ("
<< flat_emb_.size() << " embeddings)...\n";
bool recomputed = false;
cal_ = calibrate_gallery_cached(flat_emb_, flat_actor_,
gallery_.calib_a, gallery_.calib_b,
gallery_.calib_valid, gallery_.calib_hash,
cfg.gallery_path + ".calib_cache", recomputed);
if (recomputed) {
// Persist the freshly-fitted calibration into the gallery file (always
// HDF5 — save_gallery rewrites any other extension, see gallery_store.cpp)
// so the next run against this same, unchanged gallery skips the O(n^2) fit.
ActorGallery to_save = gallery_;
to_save.calib_a = cal_.a;
to_save.calib_b = cal_.b;
to_save.calib_valid = cal_.valid;
to_save.calib_hash = hash_gallery_embeddings(flat_emb_, flat_actor_);
save_gallery(cfg.gallery_path, to_save);
std::cerr << "[identity_matcher] wrote refreshed calibration back to "
<< cfg.gallery_path << "\n";
}
if (cal_.valid) {
std::cerr << "[identity_matcher] calibrated Bayesian matching"
<< " prior=" << cfg.match_prior
<< " P_threshold=" << prob_threshold_
<< " effective_sim_boundary="
<< cal_.boundary_at(prob_threshold_, log_prior_odds_) << "\n";
} else {
std::cerr << "[identity_matcher] threshold matching (calibration skipped)"
<< " threshold=" << threshold_
<< " ratio=" << ratio_ << " ratio_ceil=" << ratio_ceil_ << "\n";
}
std::cerr << "[identity_matcher] gallery: "
<< gallery_.actors.size() << " actors, "
<< flat_emb_.size() << " reference embeddings\n";
std::vector<float> host_gallery(static_cast<size_t>(n_gallery_) * 512);
for (int i = 0; i < n_gallery_; ++i)
std::memcpy(host_gallery.data() + static_cast<size_t>(i) * 512,
flat_emb_[i].data(), 512 * sizeof(float));
sim_engine_ = make_similarity_engine(host_gallery.data(), n_gallery_, kMaxFaces);
/// TRACES: AR-018, AR-024 | SR-005
// The expansion store thresholds in the same probability space as
// association and evidence weighting, so a "0.9" means one thing
// pipeline-wide rather than three.
track_gallery_.set_calibration(same_person_probability(cal_));
}
/// TRACES: AR-023, AR-024 | SR-002
/// The fitted sigmoid. Exposed because the matcher is where it gets fitted
/// (and cached back to the gallery), but it is not the matcher's private
/// property: track association and evidence weighting must threshold in the
/// *same* probability space, or a "0.5" in one stage and a "0.5" in another
/// mean different things. See `same_person_probability`.
const GalleryCalibration& calibration() const { return cal_; }
/// TRACES: AR-012, AR-025 | SR-002
/// Where per-frame identity evidence reaches the registry. Optional: with no
/// registry attached the matcher behaves exactly as before, which keeps the
/// replay harness and the unit tests working unchanged.
void set_registry(std::shared_ptr<TrackRegistry> r) { registry_ = std::move(r); }
// Runtime setter — lets a persistent pipeline be reused across a threshold sweep
// without rebuilding the (expensive, gallery-resident) matcher. The gallery,
// calibration and GPU sim-engine stay put; only the accept threshold changes.
void set_prob_threshold(float t) { prob_threshold_ = t; }
MatchedSceneFrame operator()(TrackedSceneFrame tf) {
if (tf.source.eof) {
track_gallery_.clear_tracks();
return {std::move(tf.source), {}};
}
// A hard cut changes the camera viewpoint. The face_tracker may revive a
// track_id across the cut (identity continuity), but promotion must never
// mix embeddings from two viewpoints under one buffer, so we still drop
// every diversity buffer here — a revived track simply re-accumulates its
// buffer from post-cut frames. Stale cross-cut embeddings are never promoted.
/// TRACES: AR-019 | SR-005
// Promotion may only borrow same-identity evidence from a span where
// identity is certain, so ALL THREE discontinuity signals clear the
// buffers, not just the histogram cut:
// is_cut — camera-angle change
// is_scene_boundary — different scene (AR-010; previously never set,
// so this half of the gate was dead)
// The third, an identity contradiction (AR-015), is enforced by the
// registry: a track whose belief swapped is closed outright, so it can
// no longer promote anything.
if (tf.source.is_cut || tf.source.is_scene_boundary)
track_gallery_.clear_tracks();
const int n_faces = static_cast<int>(tf.embeddings.size());
std::vector<IdentifiedActor> actors;
actors.reserve(n_faces);
if (n_faces == 0) return {std::move(tf.source), {}};
/// TRACES: AR-003, AR-004 | SR-002
// kMaxFaces sizes the similarity engine's preallocated buffer, so it
// bounds MEMORY, not how many faces a frame may contain. It used to
// throw above the bound, which made it a hard cap on crowd scenes by
// accident; now the frame is scored in batches of that size.
//
// Faces per frame are unbounded (AR-003) because X-Ray credits scene
// membership to background cast too, and a fixed cap discards exactly
// those — the smallest faces are dropped first. Cost is contained by
// backpressure (AR-004), which slows the producer, rather than by
// silently throwing work away.
std::vector<float> host_query(static_cast<size_t>(kMaxFaces) * 512);
for (int base = 0; base < n_faces; base += kMaxFaces) {
const int chunk = std::min(kMaxFaces, n_faces - base);
for (int k = 0; k < chunk; ++k) {
std::memcpy(host_query.data() + static_cast<size_t>(k) * 512,
tf.embeddings[base + k].data(), 512 * sizeof(float));
}
// S (N_gallery × chunk) col-major: face k's gallery sims at sims + k*n_gallery.
const float* host_sims = sim_engine_->compute(host_query.data(), chunk);
for (int ci = 0; ci < chunk; ++ci) {
const int fi = base + ci;
const float* sims = host_sims + static_cast<size_t>(ci) * n_gallery_;
std::vector<float> best_sim(gallery_.actors.size(),
-std::numeric_limits<float>::max());
for (int ei = 0; ei < n_gallery_; ++ei) {
float sim = sims[ei];
int ai = flat_actor_[ei];
if (sim > best_sim[ai]) best_sim[ai] = sim;
}
// Fold in the per-film annex (CPU-side, tens of embeddings). Promoted
// pose-varied views compete for best-of-N exactly like baked refs, so
// a face at a pose the gallery lacked can now win its true actor.
for (const auto& ae : track_gallery_.annex()) {
float sim = cosine_similarity(tf.embeddings[fi], ae.emb);
if (sim > best_sim[ae.actor_idx]) best_sim[ae.actor_idx] = sim;
}
int best_actor = -1;
int second_actor = -1;
float best_s = -std::numeric_limits<float>::max();
float second_s = -std::numeric_limits<float>::max();
for (int ai = 0; ai < static_cast<int>(best_sim.size()); ++ai) {
if (best_sim[ai] > best_s) {
second_s = best_s;
second_actor = best_actor;
best_s = best_sim[ai];
best_actor = ai;
} else if (best_sim[ai] > second_s) {
second_s = best_sim[ai];
second_actor = ai;
}
}
(void)second_actor;
bool accept = false;
if (best_actor >= 0) {
if (cal_.valid) {
accept = cal_.probability(best_s, log_prior_odds_) > prob_threshold_;
} else {
float best_d = 1.f - best_s;
float second_d = (second_s > -std::numeric_limits<float>::max())
? 1.f - second_s
: std::numeric_limits<float>::max();
bool absolute = best_d < threshold_;
bool ratio = (best_d < ratio_ceil_) &&
(second_d == std::numeric_limits<float>::max() ||
best_d / second_d < ratio_);
accept = absolute || ratio;
}
}
IdentifiedActor ia;
// Map bbox back to original video resolution when dense_scale
// downscaled the decoded frame (detection/tracking ran downscaled;
// output bboxes must be in original pixel space).
ia.bbox = tf.faces[fi].bbox;
if (tf.source.bbox_upscale != 1.f) {
const float s = tf.source.bbox_upscale;
ia.bbox.x *= s; ia.bbox.y *= s;
ia.bbox.width *= s; ia.bbox.height *= s;
}
ia.crop = tf.crops[fi];
ia.track_id = tf.track_ids[fi];
if (accept) {
ia.actor_idx = best_actor;
ia.name = gallery_.actors[best_actor].name;
ia.imdb_id = gallery_.actors[best_actor].imdb_id;
ia.tmdb_id = gallery_.actors[best_actor].tmdb_id;
ia.jellyfin_id = gallery_.actors[best_actor].jellyfin_id;
ia.similarity = cal_.valid
? cal_.probability(best_s, log_prior_odds_)
: best_s;
}
// Feed this face into per-film gallery expansion. best_actor/best_s
// reflect the actor with the strongest gallery similarity for this
// face (annex already folded in above); the track's diversity buffer
// keeps the gallery-far views and promotes them once the track is
// confirmed. No-op unless --expand-gallery is set.
// TRACES: AR-012, AR-025 | SR-002
// Every scored face is evidence, not only the accepted ones: a run of
// near-misses for one actor is itself informative, and discarding it
// would make ownership depend on a per-frame threshold the redesign
// exists to stop relying on. The registry discounts for correlation
// and decides ownership from the accumulated posterior (AR-025).
if (registry_ && best_actor >= 0 && tf.track_ids[fi] >= 0) {
const float p = cal_.valid
? cal_.probability(best_s, log_prior_odds_)
: std::max(0.f, best_s);
registry_->observe(tf.track_ids[fi], best_actor, p, tf.embeddings[fi]);
}
// TRACES: AR-019 | SR-005
// Ownership is the registry's, computed once. TrackGallery used to
// tally its own plurality vote over accepted frames, which meant two
// different answers to "who is this track" could coexist — and the
// expansion one ignored the Bayesian accumulation entirely.
if (registry_ && tf.track_ids[fi] >= 0) {
if (auto owner = registry_->owner(tf.track_ids[fi]))
track_gallery_.set_owner(tf.track_ids[fi], *owner);
}
track_gallery_.observe(tf.track_ids[fi], tf.embeddings[fi],
best_actor, best_s, accept, tf.crops[fi]);
actors.push_back(std::move(ia));
}
} // chunk loop
return {std::move(tf.source), std::move(actors)};
}
private:
ActorGallery gallery_;
GalleryCalibration cal_;
float prob_threshold_;
float log_prior_odds_;
float threshold_;
float ratio_;
float ratio_ceil_;
std::vector<Embedding> flat_emb_;
std::vector<int> flat_actor_;
int n_gallery_{0};
std::unique_ptr<ISimilarityEngine> sim_engine_;
TrackGallery track_gallery_;
std::shared_ptr<TrackRegistry> registry_;
};