dvb-conformance 9.2.0

# dvb-conformance

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ETSI TR 101 290 v1.4.1 transport-stream conformance monitor (DVB measurement
guidelines). Feed TS packets with a caller-supplied monotonic clock, drain
structured conformance events per indicator.

## Quick start

```rust
use dvb_conformance::{ConformanceMonitor, ConformanceEvent, Indicator};
use core::time::Duration;

let mut monitor = ConformanceMonitor::new();  // default config

let mut t = Duration::ZERO;
for packet in ts_packets {
    t += Duration::from_micros(188 * 8 * 1_000_000 / 6_000_000); // ≈188 bytes @ 6 Mbit/s
    for event in monitor.feed(packet, t) {
        eprintln!("[{:?}] {}: {}", event.priority, event.indicator.name(), event.detail);
    }
}
```

Use `ConformanceMonitor::with_config(Config { .. })` to tune thresholds (PAT/PMT
max intervals, PCR repetition and discontinuity limits, SI repetition intervals, etc.).

## What's implemented

### Indicators — 23 implemented, per the `Indicator` enum in `src/lib.rs`

| Priority | Clause | Indicator | Notes |
|----------|--------|-----------|-------|
| 1 | 1.1 | `TsSyncLoss` | Hysteresis: 5 consecutive good → in-sync; 2 consecutive bad → sync lost |
| 1 | 1.2 | `SyncByteError` | `sync_byte != 0x47` on any packet |
| 1 | 1.3.a | `PatError2` | PAT absent > 500 ms (default); wrong table_id or scrambled on PID 0x0000 |
| 1 | 1.4 | `ContinuityCountError` | CC wrap + duplicate-packet allowance (one dup per sequence) |
| 1 | 1.5.a | `PmtError2` | PMT absent > 500 ms per `program_map_PID`; scrambled on PMT PID |
| 1 | 1.6 | `PidError` | Referenced ES PID absent > 5 s (default) |
| 2 | 2.1 | `TransportError` | `transport_error_indicator` set |
| 2 | 2.2 | `CrcError` | CRC-32 mismatch on completed long-form SI/PSI section |
| 2 | 2.3a | `PcrRepetitionError` | PCR interval > 100 ms (default) on any PCR-carrying PID |
| 2 | 2.3b | `PcrDiscontinuityError` | PCR delta > 100 ms (default) without `discontinuity_indicator` |
| 2 | 2.5 | `PtsError` | PTS interval > 700 ms (default) on ES PIDs |
| 2 | 2.6 | `CatError` | Wrong table_id on PID 0x0001; scrambled packet with no CAT seen |
| 3 | 3.1 | `NitError` | Bad table_id on PID 0x0010 (not NIT_actual/NIT_other/ST); NIT_actual absent > 10 s (default) |
| 3 | 3.2 | `SiRepetitionError` | Max-interval dimension: NIT_actual (10 s), SDT_actual (2 s), EIT P/F actual (2 s), TDT (30 s); min-gap (25 ms) shared by 3.1.a/3.2/3.5.a/3.6.a/3.7/3.8 via `SiMinGapError` |
| 3 | 3.4 | `UnreferencedPid` | A PID persists > 500 ms (default) without being referenced by the PAT/CAT/a PMT or a well-known SI PID |
| 3 | 3.5 | `SdtError` | Bad table_id on PID 0x0011 (not SDT_actual/SDT_other/BAT/ST); SDT_actual absent > 2 s (default) |
| 3 | 3.6 | `EitError` | Bad table_id on PID 0x0012 (not EIT P/F or schedule range 0x50–0x6F or ST); EIT P/F actual absent > 2 s (default) |
| 3 | 3.7 | `RstError` | Bad table_id on PID 0x0013 (not RST/ST) |
| 3 | 3.8 | `TdtError` | Bad table_id on PID 0x0014 (not TDT/TOT/ST); TDT absent > 30 s (default) |

### New indicators (P3 deferred, #736)

| Priority | Clause | Indicator | Notes |
|----------|--------|-----------|-------|
| 3 | 3.6.c | `EitPfError` | EIT P/F sub-table missing one of its two sections (per-service, not global) |
| 3 | 3.1.b | `NitOtherError` | NIT_other (0x41) sections with same `section_number` > 10 s apart; fires only after presence established |
| 3 | 3.5.b | `SdtOtherError` | SDT_other (0x46) sections with same `section_number` > 10 s apart; fires only after presence established |
| 3 | 3.6.b | `EitOtherError` | EIT P/F other (0x4F) sections with same `section_number` > 10 s apart; fires only after presence established |
| 3 | — | `SiMinGapError` | Two sections of same `(table_id, section_number)` < 25 ms apart (shared by 3.1.a/3.2/3.5.a/3.6.a/3.7/3.8) |

### New indicators (T-STD, #737)

| Priority | Clause | Indicator | Notes |
|----------|--------|-----------|-------|
| 2 | 2.4 | `PcrAccuracyError` | **Not implemented** — requires hardware arrival timing with ±500 ns resolution (ISO/IEC 13818-1 §2.4.2.2); the variant exists for documentation completeness only; never emitted |
| 3 | 3.3 | `BufferError` | TBsys overflow (512-byte buffer, 1 Mbit/s drain); TBn overflow deferred (needs coded bitrate Rxn from descriptors) |
| 3 | 3.9 | `EmptyBufferError` | TBn/TBsys empty at least once per second; MBn check deferred (needs leak-method parameters from descriptors) |
| 3 | 3.10 | `DataDelayError` | Data delay through T-STD transport buffers > 1 s; still-picture 60 s threshold NOT implemented — requires PMT stream_type detection from descriptors |

### T-STD buffer model (#737)

A partial ISO/IEC 13818-1 T-STD buffer model (see `src/tstd.rs`) drives
indicators 3.3, 3.9, and 3.10:

- **TBn** (per-PID, 512 bytes): modelled for empty-interval and data-delay
  tracking. Overflow detection is **deferred** — it requires the coded bitrate
  `Rxn` from descriptors (multiplex_buffer_descriptor).
- **TBsys** (global, 512 bytes, 1 Mbit/s drain): fed at PSI section completion.
  Overflow (firewall), empty-interval, and data-delay checks are implemented.
- **MBn / EBn / Bn / Bsys**: **deferred** — these require codec-level buffer
  sizes from descriptors and are not yet parsed by the monitor.

All buffer sizes and rates are named constants citing the vendored ITU-T
H.222.0 v9 (08/2023) PDF. The full transcription is at
`dvb-conformance/docs/h222_0-tstd-buffer-model.md`.

| Constant | Value | H.222.0 clause |
|----------|-------|----------------|
| TBn / TBsys size | 512 bytes | §2.4.2.4, p.42: "The transport buffer size is fixed at 512 bytes" |
| TBsys drain rate | 1 Mbit/s | §2.4.2.4, p.42: "For systems data: Rxn = 1×10⁶ bits per second" |
| Bsys size | 1536 bytes | §2.4.2.4, p.43: "The main buffer Bsys … size BSsys = 1536 bytes" (deferred) |
| TB leak rate floor | 125 kbit/s | Modelling floor, not a spec value (Rxn ≥ 2×10⁶ bps per §2.4.2.4) |

**Note on 2.4 PCR_accuracy_error**: this indicator requires hardware arrival
timestamps with ±500 ns accuracy. The monitor is sans-IO with a
caller-supplied clock; a packet-index-derived timing estimate cannot
honestly resolve 500 ns. A false positive here is worse than a gap
(cf. the withdrawn `PtsCheck`). The indicator exists in the enum for
documentation completeness but is never emitted.

Excluded, split by reason:

**Not computable without hardware arrival timing** (needs ±500 ns resolution):

| Clause | Indicator | Reason |
|--------|-----------|--------|
| 2.4 | `PCR_accuracy_error` | Requires ±500 ns PCR accuracy measurement against a hardware reference clock (ISO/IEC 13818-1 §2.4.2.2); a packet-index-derived arrival estimate cannot resolve 500 ns |

**Partially implemented — TBn overflow / MBn / EBn / Bn / Bsys deferred**
(needs codec-dependent buffer-size descriptors not yet parsed by the monitor):

| Clause | Indicator | Deferred sub-checks |
|--------|-----------|---------------------|
| 3.3 | `Buffer_error` | TBn overflow (needs Rxn from descriptors); MBn/EBn/Bn underflow/overflow; Bsys overflow |
| 3.9 | `Empty_buffer_error` | MBn empty-at-least-once-per-second (leak method) |
| 3.10 | `Data_delay_error` | Still-picture video data 60 s threshold differentiation; MBn delay |

**Feasible, deferred** (reusable with the existing timer machinery, but not
yet implemented):

None — all previously deferred Priority-3 dimensions (25 ms min-gap, `_other`
repetition, EIT P/F pairing) were implemented in #736. See the table above.

### Caller-supplied time model

`ConformanceMonitor::feed(packet, t)` takes a `core::time::Duration` alongside
each TS packet. The monitor uses this clock for all presence/absence timeout
checks (1.3.a, 1.5.a, 1.6, 2.3a, 2.3b, 2.5, 3.2). The caller must supply
monotonic non-decreasing timestamps; the monitor does not enforce this but
non-monotonic timestamps will produce spurious events. Because there is no
independent hardware clock, PCR accuracy (2.4) and buffer-model indicators are
not computable.

### SI_repetition_error (3.2) — implementation notes

- Maximum-interval checks are implemented for NIT_actual (10 s), SDT_actual
  (2 s), EIT P/F actual (2 s), and TDT (30 s). Each table's timer is lazily
  armed — checking starts only after the first section of that table is seen;
  an entirely absent table is not flagged by this indicator (that is the role
  of the out-of-scope per-table presence indicators).
- EIT P/F is tracked at the table level (any section with table_id `0x4E`
  resets the timer), not per section_number, to avoid false positives on dense
  EIT schedules.

### PAT-following PMT discovery

The monitor parses each completed PAT section and automatically starts tracking
the `program_map_PID` entries it finds, enabling indicator 1.5.a (PMT absence)
and ES PID extraction (indicator 1.6).

### NIT/SDT/EIT/RST/TDT_error (3.1, 3.5, 3.6, 3.7, 3.8) — implementation notes

- Each indicator validates the `table_id` of every completed section on its
  well-known PID against the allowed set from `docs/tr_101_290.md` clause
  3.x, firing immediately on a disallowed value.
- The absence dimension of 3.1/3.5/3.6/3.8 (NIT_actual/SDT_actual/EIT P/F
  actual/TDT missing beyond the repetition interval) is raised from the
  *same* lazily-armed timer that drives `SiRepetitionError` (3.2) — the two
  indicators are the same underlying absence event with two spec identities
  (the old combined indicator vs. the newer split `_actual` variant); both
  fire together.
- `RstError` (3.7) has no documented absence threshold in Table 5.0c, so it
  only has the bad-table_id dimension.

### Unreferenced_PID (3.4) — implementation notes

- Tracks the first-seen time of any PID that is not (yet) part of the
  referenced set: PAT, CAT, the well-known SI PIDs (NIT/SDT-BAT/EIT/RST/
  TDT-TOT), the null PID, the reserved-for-future-use range (0x0002–0x000F),
  `program_map_PID`s from the PAT, and ES/PCR PIDs from a PMT. A PID that
  persists past the 500 ms (default) threshold without becoming referenced
  raises `UnreferencedPid`.
- **Known limitations** (documented, not silently swallowed): CAT-referenced
  EMM PIDs are not exempted — this monitor validates CAT `table_id` but does
  not decode CA descriptors to extract `CA_PID`s. PIDs "user defined as
  private data streams" (the spec's own carve-out) are likewise not
  distinguishable from the wire alone. Either can produce a false positive
  for a stream using that pattern; the crate does not currently model it.

## Feature flags

| Feature | Default | Description |
|---------|---------|-------------|
| `std` | **on** | Link the standard library. Without it the crate is `#![no_std]` + `alloc`. |
| `serde` | **on** | Serialize-only (`serde::Serialize`) on `ConformanceEvent`, `Indicator`, `Priority`, `Stats`. |

## MSRV

Rust **1.86**.

## References

- ETSI TR 101 290 v1.4.1 (2020-06) — DVB Measurement Guidelines (§5.2.1 Table 5.0a, §5.2.2 Table 5.0b, §5.2.3 Table 5.0c)
- ISO/IEC 13818-1 — MPEG-2 Systems

## Examples

Run with `cargo run -p dvb-conformance --example <name>`:

- **`monitor_stream`** — run the TR 101 290 monitor over a capture and print the headline stats.
- **`priority_breakdown`** — tally findings by measurement priority (1/2/3) and indicator.

## License

Licensed under either of MIT ([LICENSE-MIT](../LICENSE-MIT)) or Apache-2.0
([LICENSE-APACHE](../LICENSE-APACHE)), at your option.