α-7 (monotonic timestamp counter) changed wire bytes but H.264 output
unchanged (71ac099b...). Confirms Phase 5 CRIT-1 prediction: VP9/MPEG-2
PASS via libva with the same v4l2_timeval_to_ns(&ref->timestamp)
pattern; therefore timestamp magnitude was never load-bearing.
5-codec regression sweep: all 4 non-H.264 anchors hold. Zero regression.
Cumulative state after iter8+iter9:
- 6 hypotheses eliminated (libva-readback, slot-binding, stale-residue,
constraint_set_flags, POC sentinel, reference_ts magnitude)
- libva-vs-kdirect H.264 wire-byte diff is now empirically zero
- α-2 + α-7 shipped as wire-payload hygiene cleanups (zero behavior
change but cleaner semantics)
iter10 candidate ranking:
1. α-8 OUTPUT bitstream byte dump (compare in-memory slice bytes)
2. α-9 untraced control diff (device-wide controls beyond DECODE_MODE
+ START_CODE)
3. Kernel-side investigation (rkvdec source dive for 16x32 partial-
decode signature)
4. Pivot to Bug 5 (HEVC) or Bug 6 (VP8)
Two more iterations of diminishing returns suggest either deeper
empirical work (OUTPUT-byte dump or kernel investigation) or pivot
to a different bug.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
