Crate dash_runtime 

Sans-IO MPEG-DASH: the MPD model and parser, segment addressing, the UTC clock and the live-edge arithmetic a DASH client is built on, and client::DashClient, a client state machine for static (VOD) and dynamic (live) presentations.

Spec: ISO/IEC 23009-1:2022 (clause 5.3 MPD, 5.3.9 Segment information, 5.6 BaseURL, 5.8.5.7 UTCTiming, Annex A client behaviour, Annex I URL parameters), DASH-IF IOP v4.3 (live timing) and ETSI TS 103 285 (BaseURL priority). The verified page references are in the private spec repository (private/specs-verified/dash/docs-specs/); decisions where the standard contradicts itself are in docs/dash-runtime/DESIGN.md section 11.

Nothing here does I/O or reads a clock. Every instant is an argument; the caller fetches the MPD, the sidx and the segments, times its own requests, and asks this crate what to fetch and when it becomes available.

Module	What it gives
mpd	mpd::Mpd: the consume-only model, a bounded namespace-aware parser, attribute inheritance down Period > AdaptationSet > Representation, BaseURL alternates and URL resolution
address	address::SegmentPlan: the lazy Segment list of a Representation (templates with width tags and $$, timelines with negative @r and @n, SegmentList, SegmentBase + sidx), with availability windows
timing	timing::clock::UtcClock, UTCTiming sampling, xs:dateTime / HTTP Date / NTP readers, PeriodStart, availability and live-edge arithmetic
client	client::config::DashConfig: the DASH knobs of a client session (clock ladder, early-request cadence, refresh floor)
selection	Pure choice of AdaptationSet and Representation by role, language, codec and bandwidth
client	client::DashClient: plays static and dynamic MPDs to ordered Fmp4Demux samples, with typed failure classes, Period continuity and an origin pin

Format policy

The model is consume-only: there is no MPD serializer. The workspace round-trip invariant is met against transmux’s DASH generator by a differential test (tests/differential.rs): everything the generator writes is parsed, and the two parsers agree on every field both read, the expanded segment numbers and times, and the resolved URLs.

Scope of 0.1

The client plays static and dynamic MPDs: a dynamic one gets a clock (UTCTiming, the host clock via DashClient::set_wall_clock, or the MPD response Date), a join near the live edge, availability gating and MPD refresh.

The core handles: static and dynamic MPDs, SegmentTemplate ($Number$, $Time$, $Bandwidth$, $RepresentationID$), SegmentTimeline, SegmentList, SegmentBase with a sidx, BaseURL alternates, multiple Periods, UTCTiming (direct, http-xsdate, http-iso, http-head, http-ntp). Typed Unsupported (the Representation is dropped, never misread): segment sequences (S@k, $SubNumber$), MPD@type="list", data: addresses, open-ended byte ranges, hierarchical sidx.

Examples

• cargo run -p dash-runtime --example list_segments prints the segment URLs of an MPD file.
• cargo run -p dash-runtime --example live_window prints the live edge of a dynamic MPD at a simulated clock.
• cargo run -p dash-runtime --example play_live plays a dynamic MPD against a loopback origin and a simulated clock.
• cargo run -p dash-runtime --example play_static plays a static MPD from the file system through DashClient and prints what a host receives.

use dash_runtime::address::{PlanOptions, plan_representation};
use dash_runtime::mpd::Mpd;
use dash_runtime::selection::RepRef;

let xml = r#"<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" type="static"
                  mediaPresentationDuration="PT6S">
  <Period><AdaptationSet mimeType="video/mp4">
    <SegmentTemplate timescale="1000" duration="2000" startNumber="0"
                     media="$RepresentationID$/$Number%03d$.m4s"/>
    <Representation id="v1" bandwidth="500000"/>
  </AdaptationSet></Period>
</MPD>"#;
let mpd = Mpd::parse(xml.as_bytes()).unwrap();
let planned = plan_representation(&mpd, RepRef::at(0, 0, 0), &PlanOptions::default()).unwrap();
let refs: Vec<_> = planned.plan.iter().map(|s| s.reference).collect();
assert_eq!(refs, ["v1/000.m4s", "v1/001.m4s", "v1/002.m4s"]);

Modules

address

Representation to Segment plan (ISO/IEC 23009-1 5.3.9.2-5.3.9.6).

client

The sans-IO DASH client for static (VOD) presentations (docs/dash-runtime/DESIGN.md sections 1, 5 and 7).

error

Typed errors for MPD parsing.

limits

Hostile-input bounds for MPD parsing and segment expansion.

mpd

MPD model and parser (ISO/IEC 23009-1 clause 5.3, Annex B).

selection

Pure selection of AdaptationSets and Representations (docs/dash-runtime/DESIGN.md 5.1), by role, language, codec and bandwidth, into the variant model a host speaks.

timing

Pure time arithmetic: UTC clock, xs:dateTime, UTCTiming, availability, live edge and PeriodStart. Nothing in this module reads a clock; every function takes the instants it needs as arguments.