The periodic TX timer had an arbitrary phase against packet boundaries,
so packets waited up to one packet time (different after every restart).
- One-shot esp_timer aimed at the next packet's due time from PTP, with
the clock re-read after sending.
- 1 kHz tone from a per-rate lookup table (one period = rate/1000
samples) instead of sinf() per sample.
Measured (RTP time - arrival, 4 ms vs 1 ms packets, expected -3.07 ms
incl. wire time): -3.3 ms extra before, now -3.14 ms. Tone within
1.0 LSB of the ideal PTP-phased sine, no gaps.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
bsncubed
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