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SourceElement

media_pp::element

Trait SourceElement 

Source 
pub trait SourceElement: Source {
    // Required methods
    fn run(&mut self, control: &ControlReceiver, bus: &Bus) -> Result<()>;
    fn seek(&mut self, target: Duration) -> Result<Duration>;
}
Expand description

A pure source: has output but no input. Its run method drives the production loop and pushes buffers into its own src pad(s) until EOS or an error. crate::pipeline::Pipeline::run normally invokes that loop on the pipeline’s background source thread; a caller may also invoke a concrete implementation directly. Sources typically wrap blocking I/O reads (demuxer, file/network source).

Required Methods§

Source

fn run(&mut self, control: &ControlReceiver, bus: &Bus) -> Result<()>

Drives this source until Eos (normal completion), crate::pipeline::Pipeline::finish, or Stop (see ControlMsg::Stop) — call crate::control::drain_control once per loop iteration to make control responsive between blocking reads.

bus is this source’s own way to report a failure pushing into one of its pads without treating it as fatal — post a crate::bus::BusEvent::Error and keep going (drop that one buffer), the same way a crate::queue::Queue handles a failing downstream Sink — rather than returning Err and ending this source’s thread over one bad buffer. A returned Err is still how genuinely fatal failures (this source can’t continue at all) reach crate::pipeline::Pipeline::run, which posts it to bus itself.

Source

fn seek(&mut self, target: Duration) -> Result<Duration>

Repositions this source to target, an absolute position from the start of the media (e.g. av_seek_frame for crate::elements::FileDemuxer). Called by crate::control::drain_control as part of handling ControlMsg::Seek, before that message is forwarded to the source’s own pads — so whatever’s read next comes from the new position by the time downstream elements are told to flush for it.

Returns where this actually landed, which is allowed to differ from target — a container seek can only ever reposition to a keyframe at or before it (landing mid-GOP would leave downstream decoders/muxers with no reference frame to start from), so target is a request, not a guarantee. drain_control reports the gap between the two via crate::bus::BusEvent::Seeked; callers that need to know where playback actually resumed should watch that instead of assuming target took effect verbatim.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§