QoS profiles

Generated from packages/seyd-qos/src/lib.rs. A profile is a ceiling: the closed-loop controller moves the bitrate request and the FEC rates inside it, never above it. The robot picks a profile (qos_profile in seydd.toml, seyd_set_qos_profile, Agent.set_qos_profile) and a driver may ask for another (SeydSession.setQos). Degrade resolution first and frame rate last: for a remote pilot, the interval between frames is latency, not quality.

Targets the publisher must honour (sent as video-config)

Field	latency	balanced	quality	Meaning
max_bitrate_kbps	1500	3000	6000	The ceiling on the publisher’s video bitrate; the closed-loop controller moves the actual request between 25 % of this and this.
latency_budget_ms	100	100	200	How much end-to-end delay the profile is prepared to spend, told to the publisher so it can size its own buffers (VBV, lookahead).
max_gop_ms	10000	10000	4000	The longest the publisher may go without a full recovery point — an IDR, or a completed intra-refresh sweep.
prefer_intra_refresh	true	true	true	Ask the publisher to refresh the picture gradually — a strip of intra-coded blocks per frame sweeping the picture within max_gop_ms — rather than with periodic IDRs, where its encoder can (x264, NVENC, Jetson; not the ONVIF cameras surveyed).

Seyd’s own transport policy

Field	latency	balanced	quality	Meaning
fec_delta_pct	25	15	8	Reed-Solomon parity added to a delta frame’s block, as a percentage of its data chunks, on a clean link; the controller raises it under loss.
fec_key_pct	50	30	15	Parity for keyframes, which are larger and cost a GOP if torn.
backlog_drop_frames	1	2	3	Drop a delta frame if the send backlog exceeds this many frame-times.
recovery_grace_ms	700	900	1400	How long the sender waits for a recovery point after asking for one before it resumes sending delta frames regardless.

Pilot policy

Field	latency	balanced	quality	Meaning
pilot_deadline_delta_ms	20	30	50	How long the pilot waits for a delta frame’s missing chunks before closing it out.
pilot_deadline_key_ms	40	60	100	The same wait for a keyframe.
pilot_presentation_delay_ms	50	100	150	How long the pilot holds a decoded frame past its capture slot before painting it (ADR 0005).
on_loss	Continue	Continue	FreezeUntilIdr	What the pilot does when a frame cannot be repaired: keep decoding (continue, and ask for a recovery point) or freeze until the next IDR.

Field notes

name

The profile’s name: latency, balanced or quality.

max_bitrate_kbps

The ceiling on the publisher’s video bitrate; the closed-loop controller moves the actual request between 25 % of this and this.

latency_budget_ms

How much end-to-end delay the profile is prepared to spend, told to the publisher so it can size its own buffers (VBV, lookahead).

max_gop_ms

The longest the publisher may go without a full recovery point — an IDR, or a completed intra-refresh sweep. A ceiling, and a safety net: Seyd asks for recovery points when it needs them (recovery-request), so the periodic one only has to catch a publisher that ignores it (ADR 0009). It is long on purpose: a periodic IDR is several times a delta frame, and measured on the demo camera it arrived ~22 ms late and made every GOP’s first two intervals 60 ms then 18 ms; at 10 s GOPs arrival judder fell from 3.7 to 0.9 ms mean and the stream lost 43 % of its bitrate, the IDRs’ share. A joining pilot never waits for it: the agent asks for an IDR on hello.

prefer_intra_refresh

Ask the publisher to refresh the picture gradually — a strip of intra-coded blocks per frame sweeping the picture within max_gop_ms — rather than with periodic IDRs, where its encoder can (x264, NVENC, Jetson; not the ONVIF cameras surveyed). Removes the keyframe burst entirely; measured on the sim through a shaped link as g2g p95 148 → 48 ms (docs/latency-sources.md §11).

fec_delta_pct

Reed-Solomon parity added to a delta frame’s block, as a percentage of its data chunks, on a clean link; the controller raises it under loss.

fec_key_pct

Parity for keyframes, which are larger and cost a GOP if torn.

backlog_drop_frames

Drop a delta frame if the send backlog exceeds this many frame-times.

pilot_deadline_delta_ms

How long the pilot waits for a delta frame’s missing chunks before closing it out.

pilot_deadline_key_ms

The same wait for a keyframe.

pilot_presentation_delay_ms

How long the pilot holds a decoded frame past its capture slot before painting it (ADR 0005). This is the profile’s judder-versus-latency call: a keyframe is ~8x a delta frame and is produced in one frame slot, so without a budget here the picture hitches once per GOP. It is a bound, not an average — a frame never waits longer than this past its own arrival — so it is the latency the profile is prepared to spend. 0 disables pacing and restores decode-on-arrival.

recovery_grace_ms

How long the sender waits for a recovery point after asking for one before it resumes sending delta frames regardless. A publisher that recovers with intra-refresh or an LTR reference never produces a keyframe, so waiting for one latches the stream silent forever. Roughly one refresh cycle: long enough that a real keyframe arrives first when the publisher sends IDRs, short enough that a stall is not visible as a freeze.

on_loss

What the pilot does when a frame cannot be repaired: keep decoding (continue, and ask for a recovery point) or freeze until the next IDR.