mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer-rs.git
synced 2024-10-31 22:59:14 +00:00
examples: Add an example that shows how to write subclasses with virtual methods
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1356>
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7 changed files with 516 additions and 0 deletions
1
Cargo.lock
generated
1
Cargo.lock
generated
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@ -470,6 +470,7 @@ name = "examples"
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version = "0.22.0"
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dependencies = [
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"anyhow",
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"atomic_refcell",
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"byte-slice-cast",
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"cairo-rs",
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"cocoa",
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@ -40,6 +40,7 @@ pangocairo = { git = "https://github.com/gtk-rs/gtk-rs-core", optional = true }
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raw-window-handle = { version = "0.5", optional = true }
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uds = { version = "0.4", optional = true }
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winit = { version = "0.29", optional = true, default-features = false, features = ["rwh_05"] }
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atomic_refcell = "0.1"
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[target.'cfg(windows)'.dependencies]
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windows = { version = "0.52", features=["Win32_Graphics_Direct3D11",
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186
examples/src/bin/subclass_vfuncs/iirfilter/imp.rs
Normal file
186
examples/src/bin/subclass_vfuncs/iirfilter/imp.rs
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@ -0,0 +1,186 @@
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// In the imp submodule we include the actual implementation
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use std::{collections::VecDeque, sync::Mutex};
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use glib::{once_cell::sync::Lazy, prelude::*};
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use gst_audio::subclass::prelude::*;
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use byte_slice_cast::*;
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use atomic_refcell::AtomicRefCell;
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// The debug category we use below for our filter
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pub static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
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gst::DebugCategory::new(
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"rsiirfilter",
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gst::DebugColorFlags::empty(),
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Some("Rust IIR Filter"),
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)
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});
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#[derive(Default)]
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// This is the state of our filter
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struct State {
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a: Vec<f64>,
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b: Vec<f64>,
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x: VecDeque<f64>,
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y: VecDeque<f64>,
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}
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// This is the private data of our filter
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#[derive(Default)]
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pub struct IirFilter {
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coeffs: Mutex<Option<(Vec<f64>, Vec<f64>)>>,
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state: AtomicRefCell<State>,
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}
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// This trait registers our type with the GObject object system and
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// provides the entry points for creating a new instance and setting
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// up the class data
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#[glib::object_subclass]
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impl ObjectSubclass for IirFilter {
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const NAME: &'static str = "RsIirFilter";
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const ABSTRACT: bool = true;
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type Type = super::IirFilter;
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type ParentType = gst_audio::AudioFilter;
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type Class = super::Class;
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fn class_init(class: &mut Self::Class) {
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class.set_rate = |obj, rate| obj.imp().set_rate_default(rate);
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}
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}
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// Implementation of glib::Object virtual methods
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impl ObjectImpl for IirFilter {}
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impl GstObjectImpl for IirFilter {}
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// Implementation of gst::Element virtual methods
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impl ElementImpl for IirFilter {}
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// Implementation of gst_base::BaseTransform virtual methods
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impl BaseTransformImpl for IirFilter {
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// Configure basetransform so that we are always running in-place,
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// don't passthrough on same caps and also never call transform_ip
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// in passthrough mode (which does not matter for us here).
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//
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// The way how our processing is implemented, in-place transformation
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// is simpler.
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const MODE: gst_base::subclass::BaseTransformMode =
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gst_base::subclass::BaseTransformMode::AlwaysInPlace;
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const PASSTHROUGH_ON_SAME_CAPS: bool = false;
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const TRANSFORM_IP_ON_PASSTHROUGH: bool = false;
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fn start(&self) -> Result<(), gst::ErrorMessage> {
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self.parent_start()?;
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*self.state.borrow_mut() = State::default();
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Ok(())
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}
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fn stop(&self) -> Result<(), gst::ErrorMessage> {
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self.parent_stop()?;
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*self.state.borrow_mut() = State::default();
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Ok(())
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}
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fn transform_ip(&self, buf: &mut gst::BufferRef) -> Result<gst::FlowSuccess, gst::FlowError> {
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let mut state = self.state.borrow_mut();
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// Update coefficients if new coefficients were set
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{
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let mut coeffs = self.coeffs.lock().unwrap();
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if let Some((a, b)) = coeffs.take() {
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state.x.clear();
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state.y.clear();
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if !a.is_empty() {
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state.y.resize(a.len() - 1, 0.0);
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}
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if !b.is_empty() {
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state.x.resize(b.len() - 1, 0.0);
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}
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state.a = a;
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state.b = b;
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}
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}
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if state.a.is_empty() | state.b.is_empty() {
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return Ok(gst::FlowSuccess::Ok);
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}
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let mut map = buf.map_writable().map_err(|_| {
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gst::error!(CAT, imp: self, "Failed to map buffer writable");
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gst::FlowError::Error
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})?;
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let samples = map.as_mut_slice_of::<f32>().unwrap();
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assert!(state.b.len() - 1 == state.x.len());
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assert!(state.a.len() - 1 == state.y.len());
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for sample in samples.iter_mut() {
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let mut val = state.b[0] * *sample as f64;
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for (b, x) in Iterator::zip(state.b.iter().skip(1), state.x.iter()) {
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val += b * x;
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}
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for (a, y) in Iterator::zip(state.a.iter().skip(1), state.y.iter()) {
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val -= a * y;
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}
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val /= state.a[0];
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let _ = state.x.pop_back().unwrap();
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state.x.push_front(*sample as f64);
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let _ = state.y.pop_back().unwrap();
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state.y.push_front(val);
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*sample = val as f32;
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}
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Ok(gst::FlowSuccess::Ok)
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}
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}
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impl AudioFilterImpl for IirFilter {
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fn allowed_caps() -> &'static gst::Caps {
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static CAPS: Lazy<gst::Caps> = Lazy::new(|| {
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// On both of pads we can only handle F32 mono at any sample rate.
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gst_audio::AudioCapsBuilder::new_interleaved()
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.format(gst_audio::AUDIO_FORMAT_F32)
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.channels(1)
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.build()
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});
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&CAPS
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}
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fn setup(&self, info: &gst_audio::AudioInfo) -> Result<(), gst::LoggableError> {
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self.parent_setup(info)?;
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gst::debug!(CAT, imp: self, "Rate changed to {}", info.rate());
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let obj = self.obj();
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(obj.class().as_ref().set_rate)(&obj, info.rate());
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Ok(())
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}
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}
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/// Wrappers for public methods and associated helper functions.
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impl IirFilter {
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pub(super) fn set_coeffs(&self, a: Vec<f64>, b: Vec<f64>) {
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gst::debug!(CAT, imp: self, "Setting coefficients a: {a:?}, b: {b:?}");
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*self.coeffs.lock().unwrap() = Some((a, b));
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}
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}
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/// Default virtual method implementations.
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impl IirFilter {
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fn set_rate_default(&self, _rate: u32) {}
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}
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82
examples/src/bin/subclass_vfuncs/iirfilter/mod.rs
Normal file
82
examples/src/bin/subclass_vfuncs/iirfilter/mod.rs
Normal file
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@ -0,0 +1,82 @@
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use gst::{prelude::*, subclass::prelude::*};
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use gst_audio::subclass::prelude::*;
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mod imp;
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// This here defines the public interface of our element and implements
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// the corresponding traits so that it behaves like any other gst::Element
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//
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// GObject
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// ╰──GstObject
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// ╰──GstElement
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// ╰──GstBaseTransform
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// ╰──GstAudioFilter
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// ╰──IirFilter
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glib::wrapper! {
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pub struct IirFilter(ObjectSubclass<imp::IirFilter>) @extends gst_audio::AudioFilter, gst_base::BaseTransform, gst::Element, gst::Object;
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}
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/// Trait containing extension methods for `IirFilter`.
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pub trait IirFilterExt: IsA<IirFilter> {
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// Sets the coefficients by getting access to the private struct and simply setting them
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fn set_coeffs(&self, a: Vec<f64>, b: Vec<f64>) {
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self.upcast_ref::<IirFilter>().imp().set_coeffs(a, b)
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}
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}
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impl<O: IsA<IirFilter>> IirFilterExt for O {}
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/// Trait to implement in `IirFilter` subclasses.
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pub trait IirFilterImpl: AudioFilterImpl {
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/// Called whenever the sample rate is changing.
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fn set_rate(&self, rate: u32) {
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self.parent_set_rate(rate);
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}
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}
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/// Trait containing extension methods for `IirFilterImpl`, specifically methods for chaining
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/// up to the parent implementation of virtual methods.
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pub trait IirFilterImplExt: IirFilterImpl {
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fn parent_set_rate(&self, rate: u32) {
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unsafe {
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let data = Self::type_data();
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let parent_class = &*(data.as_ref().parent_class() as *mut Class);
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(parent_class.set_rate)(self.obj().unsafe_cast_ref(), rate)
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}
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}
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}
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impl<T: IirFilterImpl> IirFilterImplExt for T {}
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/// Class struct for `IirFilter`.
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#[repr(C)]
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pub struct Class {
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parent: <<imp::IirFilter as ObjectSubclass>::ParentType as glib::ObjectType>::GlibClassType,
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set_rate: fn(&IirFilter, rate: u32),
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}
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unsafe impl ClassStruct for Class {
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type Type = imp::IirFilter;
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}
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impl std::ops::Deref for Class {
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type Target = glib::Class<<<Self as ClassStruct>::Type as ObjectSubclass>::ParentType>;
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fn deref(&self) -> &Self::Target {
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unsafe { &*(&self.parent as *const _ as *const _) }
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}
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}
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unsafe impl<T: IirFilterImpl> IsSubclassable<T> for IirFilter {
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fn class_init(class: &mut glib::Class<Self>) {
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Self::parent_class_init::<T>(class);
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let class = class.as_mut();
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class.set_rate = |obj, rate| unsafe {
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let imp = obj.unsafe_cast_ref::<T::Type>().imp();
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imp.set_rate(rate);
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};
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}
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}
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165
examples/src/bin/subclass_vfuncs/lowpass/imp.rs
Normal file
165
examples/src/bin/subclass_vfuncs/lowpass/imp.rs
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// In the imp submodule we include the actual implementation
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use std::sync::Mutex;
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use glib::{once_cell::sync::Lazy, prelude::*};
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use gst::prelude::*;
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use gst_audio::subclass::prelude::*;
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use crate::iirfilter::{IirFilterExt, IirFilterImpl};
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// These are the property values of our filter
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pub struct Settings {
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cutoff: f32,
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}
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impl Default for Settings {
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fn default() -> Self {
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Settings { cutoff: 0.0 }
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}
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}
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// This is the state of our filter
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#[derive(Default)]
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pub struct State {
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rate: Option<u32>,
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}
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// This is the private data of our filter
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#[derive(Default)]
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pub struct Lowpass {
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settings: Mutex<Settings>,
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state: Mutex<State>,
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}
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// This trait registers our type with the GObject object system and
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// provides the entry points for creating a new instance and setting
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// up the class data
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#[glib::object_subclass]
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impl ObjectSubclass for Lowpass {
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const NAME: &'static str = "RsLowpass";
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type Type = super::Lowpass;
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type ParentType = crate::iirfilter::IirFilter;
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}
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// Implementation of glib::Object virtual methods
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impl ObjectImpl for Lowpass {
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fn properties() -> &'static [glib::ParamSpec] {
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static PROPERTIES: Lazy<Vec<glib::ParamSpec>> = Lazy::new(|| {
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vec![glib::ParamSpecFloat::builder("cutoff")
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.nick("Cutoff")
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.blurb("Cutoff frequency in Hz")
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.default_value(Settings::default().cutoff)
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.minimum(0.0)
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.mutable_playing()
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.build()]
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});
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PROPERTIES.as_ref()
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}
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fn set_property(&self, _id: usize, value: &glib::Value, pspec: &glib::ParamSpec) {
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match pspec.name() {
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"cutoff" => {
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self.settings.lock().unwrap().cutoff = value.get().unwrap();
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self.calculate_coeffs();
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}
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_ => unimplemented!(),
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};
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}
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fn property(&self, _id: usize, pspec: &glib::ParamSpec) -> glib::Value {
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match pspec.name() {
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"cutoff" => self.settings.lock().unwrap().cutoff.to_value(),
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_ => unimplemented!(),
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}
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}
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}
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impl GstObjectImpl for Lowpass {}
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// Implementation of gst::Element virtual methods
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impl ElementImpl for Lowpass {
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// The element specific metadata. This information is what is visible from
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// gst-inspect-1.0 and can also be programmatically retrieved from the gst::Registry
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// after initial registration without having to load the plugin in memory.
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fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
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static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
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gst::subclass::ElementMetadata::new(
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"Lowpass Filter",
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"Filter/Effect/Audio",
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"A Lowpass audio filter",
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"Sebastian Dröge <sebastian@centricular.com>",
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)
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});
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Some(&*ELEMENT_METADATA)
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}
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}
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// Implementation of gst_base::BaseTransform virtual methods
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impl BaseTransformImpl for Lowpass {
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const MODE: gst_base::subclass::BaseTransformMode =
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<<crate::iirfilter::IirFilter as glib::object::ObjectSubclassIs>::Subclass>::MODE;
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const PASSTHROUGH_ON_SAME_CAPS: bool =
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<<crate::iirfilter::IirFilter as glib::object::ObjectSubclassIs>::Subclass>::PASSTHROUGH_ON_SAME_CAPS;
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const TRANSFORM_IP_ON_PASSTHROUGH: bool =
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<<crate::iirfilter::IirFilter as glib::object::ObjectSubclassIs>::Subclass>::TRANSFORM_IP_ON_PASSTHROUGH;
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fn start(&self) -> Result<(), gst::ErrorMessage> {
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self.parent_start()?;
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*self.state.lock().unwrap() = State::default();
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Ok(())
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}
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}
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// Implement of gst_audio::AudioFilter virtual methods
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impl AudioFilterImpl for Lowpass {}
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// Implement of IirFilter virtual methods
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impl IirFilterImpl for Lowpass {
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fn set_rate(&self, rate: u32) {
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self.state.lock().unwrap().rate = Some(rate);
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self.calculate_coeffs();
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}
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}
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impl Lowpass {
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fn calculate_coeffs(&self) {
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use std::f64;
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let Some(rate) = self.state.lock().unwrap().rate else {
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return;
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};
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let cutoff = self.settings.lock().unwrap().cutoff;
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// See Audio EQ Cookbook
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// https://www.w3.org/TR/audio-eq-cookbook
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let cutoff = cutoff as f64 / rate as f64;
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let omega = 2.0 * f64::consts::PI * cutoff;
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let q = 1.0;
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let alpha = f64::sin(omega) / (2.0 * q);
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let mut b = vec![
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(1.0 - f64::cos(omega)) / 2.0,
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1.0 - f64::cos(omega),
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(1.0 - f64::cos(omega) / 2.0),
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];
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let mut a = vec![1.0 + alpha, -2.0 * f64::cos(omega), 1.0 - alpha];
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let a0 = a[0];
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for a in &mut a {
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*a /= a0;
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}
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for b in &mut b {
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*b /= a0;
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}
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self.obj().set_coeffs(a, b);
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}
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}
|
15
examples/src/bin/subclass_vfuncs/lowpass/mod.rs
Normal file
15
examples/src/bin/subclass_vfuncs/lowpass/mod.rs
Normal file
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@ -0,0 +1,15 @@
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mod imp;
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// This here defines the public interface of our element and implements
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// the corresponding traits so that it behaves like any other gst::Element
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//
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// GObject
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// ╰──GstObject
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// ╰──GstElement
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// ╰──GstBaseTransform
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// ╰──GstAudioFilter
|
||||
// ╰──IirFilter
|
||||
// ╰──Lowpass
|
||||
glib::wrapper! {
|
||||
pub struct Lowpass(ObjectSubclass<imp::Lowpass>) @extends crate::iirfilter::IirFilter, gst_audio::AudioFilter, gst_base::BaseTransform, gst::Element, gst::Object;
|
||||
}
|
66
examples/src/bin/subclass_vfuncs/main.rs
Normal file
66
examples/src/bin/subclass_vfuncs/main.rs
Normal file
|
@ -0,0 +1,66 @@
|
|||
// This example implements a baseclass IirFilter, and a subclass Lowpass of that.
|
||||
//
|
||||
// The example shows how to provide and implement virtual methods, and how to provide non-virtual
|
||||
// methods on the base class.
|
||||
|
||||
use gst::prelude::*;
|
||||
|
||||
mod iirfilter;
|
||||
mod lowpass;
|
||||
|
||||
#[path = "../../examples-common.rs"]
|
||||
mod examples_common;
|
||||
|
||||
fn example_main() {
|
||||
gst::init().unwrap();
|
||||
|
||||
let pipeline = gst::Pipeline::new();
|
||||
let src = gst::ElementFactory::make("audiotestsrc")
|
||||
.property_from_str("wave", "white-noise")
|
||||
.build()
|
||||
.unwrap();
|
||||
let filter = glib::Object::builder::<lowpass::Lowpass>()
|
||||
.property("cutoff", 4000.0f32)
|
||||
.build();
|
||||
let conv = gst::ElementFactory::make("audioconvert").build().unwrap();
|
||||
let sink = gst::ElementFactory::make("autoaudiosink").build().unwrap();
|
||||
|
||||
pipeline
|
||||
.add_many([&src, filter.as_ref(), &conv, &sink])
|
||||
.unwrap();
|
||||
gst::Element::link_many([&src, filter.as_ref(), &conv, &sink]).unwrap();
|
||||
|
||||
let bus = pipeline.bus().unwrap();
|
||||
|
||||
pipeline
|
||||
.set_state(gst::State::Playing)
|
||||
.expect("Unable to set the pipeline to the `Playing` state");
|
||||
|
||||
for msg in bus.iter_timed(gst::ClockTime::NONE) {
|
||||
use gst::MessageView;
|
||||
|
||||
match msg.view() {
|
||||
MessageView::Eos(..) => break,
|
||||
MessageView::Error(err) => {
|
||||
println!(
|
||||
"Error from {:?}: {} ({:?})",
|
||||
err.src().map(|s| s.path_string()),
|
||||
err.error(),
|
||||
err.debug()
|
||||
);
|
||||
break;
|
||||
}
|
||||
_ => (),
|
||||
}
|
||||
}
|
||||
|
||||
pipeline
|
||||
.set_state(gst::State::Null)
|
||||
.expect("Unable to set the pipeline to the `Null` state");
|
||||
}
|
||||
|
||||
fn main() {
|
||||
// tutorials_common::run is only required to set up the application environment on macOS
|
||||
// (but not necessary in normal Cocoa applications where this is set up automatically)
|
||||
examples_common::run(example_main);
|
||||
}
|
Loading…
Reference in a new issue