media-core/engine/timebase.zig

Página generada desde native/zig/media-core/media_engine.zig. No se edita a mano: bun run docs:gen la regenera y bun run docs:check falla si difiere.

Time-base arithmetic shared by both engines and the packager. One place decides rounding, so a keyframe index, a segment plan and a packet compare equal when they describe the same instant.

Intermediate products are exact: i128 when every time-base term fits 32 bits (the common case: ISOBMFF timescales, libav AVRational), i256 when a term does not (a Matroska TimestampScale is an untrusted u64). Results that do not fit i64 saturate instead of wrapping or trapping (inputs are untrusted).

timebase.max_timeline_ticksCopiar enlace

const · línea 33

pub const max_timeline_ticks: i64 = (1 << 62) - 1

Timeline bound of the engine (ZC6-P1-01). Every timestamp or duration a demuxer hands out, in its own ticks, satisfies inTimeline: at most 2^62 - 1 ticks in magnitude (so the sum or difference of any two fits i64: DTS synthesis, pts - dts, dts + duration, segment spans), and an instant of at most 2^52 µs (~142 years; epoch timestamps fit) once converted (so the µs arithmetic of plans and indexes cannot saturate). Parsers check it where they read a timestamp from the file; the contract checks it again on every packet of either engine.

timebase.max_timeline_usCopiar enlace

const · línea 34

pub const max_timeline_us: i64 = 1 << 52

Sin ///.

timebase.inTimelineCopiar enlace

fn · línea 36

pub fn inTimeline(v: i64, tb: Rational) bool

Sin ///.

timebase.toUsCopiar enlace

fn · línea 42

pub fn toUs(v: i64, tb: Rational) i64

v (in tb units) to microseconds, rounding toward -inf. Same rule as the container parsers use for keyframe indexes (ticksToUs).

timebase.rescaleCopiar enlace

fn · línea 56

pub fn rescale(v: i64, from: Rational, to: Rational) i64

v from time base from to to, rounding to nearest with ties away from zero (libavutil av_rescale_q, AV_ROUND_NEAR_INF): both engines map a source timestamp to the same output tick.

timebase.outputTimescaleCopiar enlace

fn · línea 75

pub fn outputTimescale(kind: facts.Kind, source: Rational, sample_rate: ?u32) u32

Output timescale of a track in fMP4 (the rule movenc applies, so both engines emit the same one): audio at its sample rate; video at the source time-base denominator, doubled until it reaches 10000 (a 1/1000 Matroska time base becomes 1/16000, an exact multiple).