Struct retina::Timestamp

pub struct Timestamp { /* private fields */ }

An annotated RTP timestamp.

This couples together three pieces of information:

• The stream’s starting time. In client use, this is often as received in the RTSP RTP-Info header but may be controlled via crate::client::InitialTimestampPolicy. According to RFC 3550 section 5.1, “the initial value of the timestamp SHOULD be random”.

• The codec-specific clock rate.

• The timestamp as an i64. In client use, its top bits should be inferred from wraparounds of 32-bit RTP timestamps. The Retina client’s policy is that timestamps that differ by more than i32::MAX from previous timestamps are treated as backwards jumps. It’s allowed for a timestamp to indicate a time before the stream’s starting point.

In combination, these allow conversion to “normal play time” (NPT): seconds since start of the stream.

According to RFC 3550 section 5.1, RTP timestamps “MUST be derived from a clock that increments monotonically”. In practice, many RTP servers violate this. The Retina client allows such violations unless crate::client::PlayOptions::enforce_timestamps_with_max_jump_secs says otherwise.

Timestamp can’t represent timestamps which overflow/underflow i64 can’t be constructed or elapsed times (elapsed = timestamp - start) which underflow i64. The client will return error in these cases. This should rarely cause problems. It’d take ~2^32 packets (~4 billion) to advance the time this far forward or backward even with a hostile server.

The Display and Debug implementations currently display:

• the bottom 32 bits, as seen in RTP packet headers. This advances at a codec-specified clock rate.
• the full timestamp.
• NPT

Implementations

impl Timestamp

pub fn new(timestamp: i64, clock_rate: NonZeroU32, start: u32) -> Option<Self>

Creates a new timestamp unless timestamp - start underflows.

pub fn timestamp(&self) -> i64

Returns time since some arbitrary point before the stream started.

pub fn start(&self) -> u32

Returns timestamp of the start of the stream.

pub fn clock_rate(&self) -> NonZeroU32

Returns codec-specified clock rate, in Hz.

pub fn elapsed(&self) -> i64

Returns elapsed time since the stream start in clock rate units.

pub fn elapsed_secs(&self) -> f64

Returns elapsed time since the stream start in seconds, aka “normal play time” (NPT).

pub fn try_add(&self, delta: u32) -> Option<Self>

Returns self + delta unless it would overflow.

Trait Implementations

impl Clone for Timestamp

fn clone(&self) -> Timestamp

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Timestamp

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Timestamp

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Timestamp

fn eq(&self, other: &Timestamp) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Timestamp

impl Eq for Timestamp

impl StructuralEq for Timestamp

impl StructuralPartialEq for Timestamp