Module source 

Elements that produce buffers.

Three shapes live here. Readers pull from something that already exists — a container, an RTSP stream, a capture device, or the application itself through AppSource. Generators synthesize (TestVideoSource, TestAudioSource). And fan-in elements (AudioMixer and the video compositors) are sources with inputs: they accept buffers from several upstream branches and emit one combined stream on their own schedule.

Pipeline::new builds the common single-source case. PipelineBuilder can register one or more of these in the same pipeline; each one’s SourceElement::run loop drives its own branches on a separate background thread.

Structs

AppSource

A source whose data comes from application code pushing buffers in, rather than this element reading them itself — GStreamer’s appsrc equivalent, the reverse of crate::elements::AppSink. Push encoded MediaBuffer::Packets (straight into a decoder) or already-decoded MediaBuffer::Video/MediaBuffer::Audio (e.g. frames from a camera SDK, or synthetic test data) via AppSourceHandle, from any thread — a live capture callback, a network receive loop, a test.

AppSourceHandle

A cheaply-cloneable handle for pushing buffers into an AppSource from any thread — Clone is just two refcount bumps (name and the channel sender are both cheap to share).

AudioMixer

Sums an arbitrary, dynamically-changing number of audio sources into one output stream — the structural mirror of crate::elements::Tee: Tee is one input fanned out to a dynamic set of outputs behind a lock; AudioMixer is a dynamic set of inputs (added/removed via MixerHandle, from whatever thread each one’s own source pipeline runs on) summed into one output. Unlike Tee, which is a passive Sink driven entirely by whatever calls consume, AudioMixer has to drive itself: it’s a SourceElement with its own run thread, ticking every TICK_INTERVAL to sum however many samples each currently-attached input has ready — because mixing has to keep producing something on a steady clock even when some (or all) inputs have gone quiet, the same reason WasapiCaptureSource synthesizes silence for gaps rather than just emitting nothing.

AudioMixerOptions

Construction-time options for AudioMixer::new — the mixer’s fixed output format. Every input is resampled to match this on the way in (see InputBuffer::push); the mixer never adapts to whatever an input happens to produce.

FileDemuxer

Demuxes a file, exposing one src pad per container stream (indexed the same way as StreamInfo::index). Linking a pad “selects” that stream; leaving it unlinked just drops its packets. Real demuxer I/O is blocking, so this is meant to be run as the pipeline’s source thread.

FileDemuxerHandle

Runtime control for a FileDemuxer, taken with FileDemuxer::looping_handle before the demuxer is moved into its pipeline.

MixFormat

The format every input is resampled to and every output frame carries.

MixerHandle

A cheaply-cloneable handle for adding or removing an AudioMixer’s input sources while the pipeline is running — the mirror image of crate::elements::TeeHandle: Tee lets you attach/detach outputs from another thread; this lets you attach/detach inputs. Keeps only a Weak reference for the same reason TeeHandle does: retaining a handle after the mixer’s own pipeline finishes must not keep its internal state alive forever, and every operation becomes a harmless no-op once the mixer is gone.

MixerInputSink

One AudioMixer input, returned by MixerHandle::add_source. Resamples every incoming frame to the mixer’s fixed output format and appends it to this input’s own buffer — the actual summing happens later, on AudioMixer::run’s own thread, not here. consume runs on whatever thread is driving the upstream source this got linked to (a different pipeline’s own thread, in the normal case), so every access to the shared input map goes through MixerShared’s lock.

PipelineBridge

Carries buffers from one crate::pipeline::Pipeline into another, so the two can start, end and fail independently.

PipelineBridgeHandle

A cheaply-cloneable way to connect a pipeline to a PipelineBridge, and to end it.

PipelineBridgeOptions

Construction-time options for PipelineBridge::new.

RtspOptions

Construction-time options for RtspSource::open.

RtspSource

Demuxes a live RTSP stream — the client/receive counterpart to crate::elements::RtspSink (which publishes). One src pad per stream the server advertises, same shape as crate::elements::FileDemuxer.

StreamInfo

Metadata about one stream in an opened container, reported up front so callers can decide what to build downstream before the pipeline runs.

SwVideoCompositor

Composites the latest frames from any number of independent input pipelines into one fixed-rate opaque BGRA video stream.

SwVideoCompositorHandle

A cheaply cloneable handle for adding and removing compositor inputs. It mirrors crate::elements::MixerHandle, but each registration also returns a SwVideoLayerHandle for changing that input’s placement.

SwVideoCompositorInput

The two endpoints created for one compositor input registration. Move sink into the upstream pipeline and retain layer in application code for runtime placement changes.

SwVideoCompositorInputSink

One terminal video input returned by SwVideoCompositorHandle::add_source. It stores only the latest frame, so a fast producer cannot build an unbounded queue behind a slower compositor output rate.

SwVideoLayerHandle

Thread-safe runtime placement control for one compositor input. Retaining it does not keep the input or compositor alive.

TestAudioOptions

Construction-time options for TestAudioSource::new.

TestAudioSource

Generates a synthetic sine-wave tone — GStreamer’s audiotestsrc equivalent. No real capture device involved: TestAudioSource::run fabricates however many samples wall-clock time now owes on a drift-free absolute schedule (expected = elapsed * sample_rate, needed = expected - samples_emitted — the same shape WasapiCaptureSource::fill_silence_gap/AudioMixer::mix_tick both use, not a fixed per-tick sample count, which would drift the same way a fixed-duration thread::sleep-only schedule would), stamps it with an increasing pts (one sample per tick of TestAudioSource::time_base’s units), and pushes it straight downstream — useful for exercising AudioMixer/an encoder/a muxer without a real microphone.

TestVideoOptions

Construction-time options for TestVideoSource::new.

TestVideoSource

Generates a synthetic, moving-diagonal-gradient video stream — GStreamer’s videotestsrc equivalent. No real decode/demux involved: run() fabricates one Pixel::YUV420P frame per tick, stamps it with an increasing pts (one tick per frame, in TestVideoSource::time_base’s units), and pushes it straight downstream — useful for exercising SwScaler/Pacer/D3d12Renderer/etc. without a real file or camera. D3d12Renderer in particular already handles Pixel::YUV420P on its CPU-upload path, so this can feed a renderer directly, no decoder needed.

TextLayer

Construction-time settings for one text layer, passed to D3d11VideoCompositorHandle::add_text_layer — the text sibling of super::video_layer::VideoLayer, which add_source takes the same way. font_data (raw TTF/OTF bytes; this crate bundles no font of its own) has no sane default, so — mirroring super::video_layer::VideoLayer::new, which takes the one field a caller must supply (rect) and defaults the rest — Self::new takes only font_data and defaults font_size/color/x/y, all freely reassignable before the call to add_text_layer.

VideoCompositorOptions

The compositor’s fixed output definition. Every emitted frame is an opaque ffmpeg::format::Pixel::BGRA frame at width x height.

VideoInputId

An opaque, stable identity for one compositor input registration. Replacing an input with the same name creates a different identity, so an old sink or layer handle can never affect its replacement.

VideoLayer

Runtime-adjustable spatial settings for one compositor input.

VideoRect

An output-space rectangle. Signed coordinates allow a layer to be moved partially outside the canvas while its size remains positive.

VideoSourceRect

An input-space rectangle: the part of a frame a layer draws.

Enums

AppSourceError

Errors specific to AppSource. Converts into the crate-wide Error via ? (see crate::error::Error).

AudioMixerError

Errors specific to AudioMixer. Converts into the crate-wide Error via ? (see crate::error::Error).

FileDemuxError

Errors specific to FileDemuxer. Converts into the crate-wide Error via ? (see crate::error::Error).

PipelineBridgeError

Errors specific to PipelineBridge.

RtspSourceError

Errors specific to RtspSource. Converts into the crate-wide Error via ? (see crate::error::Error).

SwVideoCompositorError

Errors specific to SwVideoCompositor.

TestAudioSourceError

Errors specific to TestAudioSource. Converts into the crate-wide Error via ? (see crate::error::Error).

TestVideoSourceError

Errors specific to TestVideoSource. Converts into the crate-wide Error via ? (see crate::error::Error).

VideoFit

How an input’s aspect ratio is mapped into its VideoRect.