Sync to v0.17.1 — drop HEVC RTP Aggregation Packets + dual-record mode gate

[snokvist]

Syncs OpenIPC/waybeam_venc from v0.16.0 → v0.17.1. Two functional changes plus docs; no protocol/port/API surface changes beyond the RTP narrowing described below.

v0.17.0 — Drop HEVC RTP Aggregation Packets (single-NAL + FU-A only)

AP (NAL type 48) removed from both backends. The wire is now single-NAL + FU-A only, the universally-supported subset of RFC 7798.

In single-slice H.265 only VPS/SPS/PPS aggregated, and bundling the parameter set into one datagram made a single loss take out the whole GOP on a lossy RF link. AP also broke single-NAL+FU-A-only (majestic-tuned) depacketizers, which forwarded type-48 packets as corrupt video. Net negative for the FPV profile.

• HevcApBuilder deleted; send_nal/prepend_param_sets no longer take a builder. VPS/SPS/PPS prepend as separate packets on IDR.
• HevcRtpStats drops ap_packets/ap_nals; [pktzr] line becomes nals N | rtp N | fill N B | single N | fu N.
• Dead h26x_util_hevc_get_layer_id/_get_tid_plus1 removed.
• Tests assert no type-48 packet is ever emitted; TRAIL_N survives single-NAL + FU paths.
• Device-verified on Star6E IMX335: [pktzr] … single N | fu N, 60 fps, 0 drops.

v0.17.1 — gate dual-VENC creation on record.mode, not record.enabled

Cherry-picked from PR #86 by @wkumik (9410bd7, authorship preserved via -x).

Dual-record mode never engaged under runtime control: with record.enabled=false + /api/v1/record/start, ps->dual stayed NULL and the record path fell back to mirror mode, capturing ch0 (stream bitrate) instead of ch1 (record.bitrate). Channel topology now follows record.mode alone; record.enabled still controls only boot auto-start. Star6E only.

• Device-verified by @wkumik on ssc338q + imx415: post-fix recording captured ch1 at 41.3 Mbps / 1.0 s GOP (was ch0 ~5.2 Mbps / 0.25 s GOP).

This sync supersedes PR #86 — that PR will be closed with credit once this lands.

Docs

Single-PID reinit findings (STAR6E_SINGLE_PID_REINIT_FINDINGS.md), REFACTORING_PLAN / README / CRASH_LOG coherence.

Verification

• SOC_BUILD=star6e make build + SOC_BUILD=maruko make build clean.
• make test — 1653 passed, 0 failed.

🤖 Generated with Claude Code