txdemo: SvcTxDemo — per-temporal-layer UEP injector for SVC-T video#112
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Showcase of the per-packet radiotap path: map each HEVC NAL's temporal_id (and IRAP/parameter-set criticality) to a PHY TxMode, so base/IDR layers fly at a robust MCS and enhancement layers ride the fast MCS — a graceful degradation staircase instead of one MCS cliff. App-level only; no WiFiDriver core change. - svc_tx.h: LayerPolicy (TID->TxMode ladder + critical override), parse_hevc_nal, default_policy, and policy_from_env (DEVOURER_SVC_LADDER='CRIT=..;T0=..;T1=..'). - SvcTxDemo: reads length-prefixed HEVC NALs, classifies, fragments to MTU, injects each at its layer's rate via build_stream_radiotap + send_packet. - RadiotapBuilder: factor parse_tx_mode_env -> reusable parse_tx_mode_str(spec) so each ladder rung is a DEVOURER_TX_RATE-style string. - tests/gen_svc_nals.py (synthetic 1:4:8:16 IDR:T0:T1:T2 stream) + tests/svc_uep_onair.sh on-air harness; CLAUDE.md note. Hardware-verified (8814 TX -> 8821 monitor, ch6): the demo's TID counts and the witness MCS histogram both reproduce the 1:4:8:16 layer mix across MCS0/1/4/7, with the robust rungs over-delivered vs the fragile ones (the UEP payoff). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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What
A demo that exploits the per-packet radiotap path (merged in #111) for SVC-T temporal-layer video: map each HEVC NAL's
temporal_id— and IRAP/parameter-set criticality — to a PHYTxMode, so the base/IDR layers fly at a robust MCS and the enhancement layers ride the fast MCS. The result is a graceful degradation staircase (60→30→15 fps as SNR drops) instead of a single MCS cliff — open-loop unequal-error-protection (UEP), a good fit for one-way wfb-ng-style links.App-level only — no change to
WiFiDrivercore behaviour; it just consumesTxMode/build_stream_radiotap/send_packet.Changes
txdemo/svc_tx_demo/svc_tx.h—LayerPolicy(TID→TxModeladder +criticaloverride),parse_hevc_nal(TID + IRAP/param-set classification from the 2-byte HEVC header),default_policy, andpolicy_from_env.txdemo/svc_tx_demo/main.cpp(SvcTxDemo) — reads length-prefixed HEVC NALs from stdin, classifies each, fragments to the radio MTU, and injects every fragment at its layer's rate.src/RadiotapBuilder.{h,cpp}— factorparse_tx_mode_env→ reusableparse_tx_mode_str(spec), so each ladder rung is aDEVOURER_TX_RATEstring.tests/gen_svc_nals.py(synthetic 1:4:8:16 IDR:T0:T1:T2 stream) +tests/svc_uep_onair.sh(on-air histogram harness);CMakeLists.txttarget; CLAUDE.md note.Config:
DEVOURER_SVC_LADDER="CRIT=MCS0/20/LDPC/STBC;T0=MCS1/20/LDPC/STBC;T1=MCS4;T2=MCS7/40/SGI"(unset → built-in default).Verification
cmake --buildclean;ctestpasses.On hardware (8814 TX → 8821 monitor, ch6): the demo's per-TID counts and the witness MCS histogram both reproduce the 1:4:8:16 layer mix across MCS0 / MCS1 / MCS4 / MCS7:
The robust rungs are over-delivered vs the fragile ones (3.9 vs 4, 14.8 vs 16) — the UEP payoff, observed. (The on-air histogram uses an all-20 MHz/no-LDPC-STBC ladder so a plain 20 MHz sniffer can decode every rung; the realistic default stacks 40 MHz/LDPC/STBC, which is a sniffer-decode limit, not a TX limit.)
🤖 Generated with Claude Code