media-doctor — DVB / MPEG-TS diagnostics

A lint-style analysis harness for MPEG-2 Transport Streams, HLS playlists, and DASH MPDs. Each [Diagnostic] checks one rule against a TS byte buffer and pushes [Finding]s into a [Report]; a small CLI runs the full set over a file. no_std + alloc (the CLI is std).

Diagnostics

Diagnostics are validated against real captures (e.g. a clean H.264+AAC stream and a multi-programme DVB capture yield zero false positives) plus crafted fault fixtures.

CLI

$ media-doctor check --input stream.ts
Findings: 0 error(s), 0 warning(s), 0 info(s)

$ media-doctor check-hls --input playlist.m3u8
Findings: 0 error(s), 0 warning(s), 0 info(s)

$ media-doctor check-dash --input manifest.mpd
Findings: 0 error(s), 0 warning(s), 0 info(s)

--json emits the report as JSON (requires the serde feature, on by default).

watch — live compliance probe (issue #665)

$ media-doctor watch --udp 239.1.1.1:5000 --metrics-addr 127.0.0.1:9090
media-doctor watch: ingesting UDP 239.1.1.1:5000, metrics on http://127.0.0.1:9090/metrics

Continuously ingests a live raw-MPEG-TS-over-UDP feed (unicast or multicast — the address's multicast-range membership decides whether the socket joins an IGMP group) and serves an always-current snapshot as Prometheus text exposition format on GET /metrics:

Metrics exposed (see media_doctor::WatchState for the full accounting):

Scope (v1): UDP only. The full product-vision idea (docs/IDEAS.md item #4) also covers SRT; that needs srt-runtime's sans-IO handshake/ARQ engine and is a follow-up issue, not implemented here. PcrCheck/CcAnomalyCheck are not separately re-wired for watch — ConformanceMonitor already computes the equivalent PCR-repetition/discontinuity and continuity-count indicators from the same per-packet data.

The ingest/metrics core (media_doctor::WatchState::feed_datagram / render_prometheus) is plain logic with no socket dependency, so it's unit-tested by feeding a real capture chunked into UDP-payload-sized pieces — no socket is ever opened in tests. The watch binary itself is a thin UdpSocket/TcpListener shell (two std::threads sharing Arc<Mutex<WatchState>>; no async runtime) around that core.

Library

use media_doctor::{Diagnostic, PtsCheck, Report};

let mut report = Report::new();
PtsCheck.run(&ts_bytes, &mut report);
for f in report.findings() {
    println!("[{:?}] {} @ {:?}", f.severity, f.rule_id, f.location);
}

HLS playlists are validated with check_playlist (legacy line-based) or check_hls_playlist (structured, using broadcast_hls::MediaPlaylist::parse). DASH MPDs are validated with check_dash_mpd (structured, using transmux::Mpd::parse).

Deferred Manifest Rules

These rules are spec-mandated but deferred from the current implementation. Each has a specific, stated reason — a rule without a reason looks like an accidental omission, which is the failure this project keeps correcting.

Deferred rules fall into three categories:

• Source not available: the spec text is not in a form this project can read (e.g. ISO/IEC 23009-1 is not vendored, so any profile rule would be fabricated).
• Information not in manifest: the manifest alone does not carry the data the rule needs (e.g. init-segment contents, cross-reload state, another playlist's content).
• Model gap: the transmux parser for the manifest doesn't carry the field the rule would inspect.

Anything not in one of these categories — most importantly, things the spec does not require — are listed separately under "Rules that are not spec requirements" below so they are never mistaken for missing checks.

HLS (RFC 8216bis)

6 deferred HLS rules (was previously counted as 7 — the tag-ordering entry was a miscount, since tag ordering is enforced by the structured parser and is not a deferred gap).

DASH (ISO/IEC 23009-1)

Rules that are not spec requirements

These are things that might look like missing checks but are simply not required by the spec. They belong here — not in the deferred list — so their absence is not mistaken for an omission.

These deferred rules are recorded here (not only in a PR body) so users know exactly what the validator does and does not check. They are also cross-referenced in the CHANGELOG.

License

MIT OR Apache-2.0.