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gst-plugin-tutorial: port-tutorial-documentation-to-new-register-API

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This commit is contained in:
Abdul Rehman 2019-10-03 19:13:56 +05:00 committed by Sebastian Dröge
parent b84388b0f3
commit 60a19826e6
2 changed files with 53 additions and 39 deletions
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51
gst-plugin-tutorial/tutorial-1.md
View file

@ -49,9 +49,12 @@ gstreamer-video = { git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs
name = "gstrstutorial"
crate-type = ["cdylib"]
path = "src/lib.rs"
[build-dependencies]
gst-plugin-version-helper = { git = "https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs" }
```
We depend on the `gstreamer`, `gstreamer-base` and `gstreamer-video` crates for various GStreamer APIs that will be used later, and the `glib` crate to be able to use some GLib API that we’ll need. GStreamer is building upon GLib, and this leaks through in various places.
We depend on the `gstreamer`, `gstreamer-base` and `gstreamer-video` crates for various GStreamer APIs that will be used later, and the `glib` crate to be able to use some GLib API that we’ll need. GStreamer is building upon GLib, and this leaks through in various places. We also have one build dependency on the `gst-plugin-version-helper` crate, which helps to get some information about the plugin for the `gst_plugin_define!` macro automatically.
With the basic project structure being set-up, we should be able to compile the project with `cargo build` now, which will download and build all dependencies and then creates a file called `target/debug/libgstrstutorial.so` (or .dll on Windows, .dylib on macOS). This is going to be our GStreamer plugin.
@ -81,16 +84,17 @@ Next we make use of the `gst_plugin_define!` `macro` from the `gstreamer` crate
```rust
gst_plugin_define!(
rstutorial,
"Rust Tutorial Plugin",
env!("CARGO_PKG_DESCRIPTION"),
plugin_init,
"1.0",
concat!(env!("CARGO_PKG_VERSION"), "-", env!("COMMIT_ID")),
"MIT/X11",
"rstutorial",
"rstutorial",
"https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs",
"2017-12-30"
env!("CARGO_PKG_NAME"),
env!("CARGO_PKG_NAME"),
env!("CARGO_PKG_REPOSITORY"),
env!("BUILD_REL_DATE")
);
```
GStreamer requires this information to be statically available in the shared library, not returned by a function.
The static plugin metadata that we provide here is
@ -104,6 +108,21 @@ The static plugin metadata that we provide here is
1. origin of the plugin
1. release date of this version
Next we create `build.rs` in the project main directory.
```rust
extern crate gst_plugin_version_helper;
fn main() {
gst_plugin_version_helper::get_info()
}
```
`build.rs` compiles and runs before anything else, [see](https://doc.rust-lang.org/cargo/reference/build-scripts.html).
Therefore, `gst_plugin_version_helper::get_info()` will provide various information via `cargo` environment variables such as `COMMIT_ID` and `BUILD_REL_DATE` and these environment variables are then later accessed by our invocation of the `gst_plugin_define!` macro during compilation.
In addition we’re defining an empty plugin entry point function that just returns `Ok(())`
```rust
@ -177,7 +196,12 @@ impl ObjectSubclass for Rgb2Gray {
}
pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
gst::Element::register(Some(plugin), "rsrgb2gray", 0, Rgb2Gray::get_type())
gst::Element::register(
Some(plugin),
"rsrgb2gray",
gst::Rank::None,
Rgb2Gray::get_type(),
)
}
```
@ -273,7 +297,12 @@ impl ElementImpl for Rgb2Gray {}
impl BaseTransformImpl for Rgb2Gray {}
pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
gst::Element::register(Some(plugin), "rsrgb2gray", 0, Rgb2Gray::get_type())
gst::Element::register(
Some(plugin),
"rsrgb2gray",
gst::Rank::None,
Rgb2Gray::get_type(),
)
}
```
@ -762,7 +791,7 @@ impl ObjectImpl for Rgb2Gray {
match *prop {
subclass::Property("invert", ..) => {
let mut settings = self.settings.lock().unwrap();
let invert = value.get().unwrap();
let invert = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: element,
@ -774,7 +803,7 @@ impl ObjectImpl for Rgb2Gray {
}
subclass::Property("shift", ..) => {
let mut settings = self.settings.lock().unwrap();
let shift = value.get().unwrap();
let shift = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: element,

41
gst-plugin-tutorial/tutorial-2.md
View file

@ -218,7 +218,7 @@ impl ObjectImpl<BaseSrc> for SineSrc {
match *prop {
Property::UInt("samples-per-buffer", ..) => {
let mut settings = self.settings.lock().unwrap();
let samples_per_buffer = value.get().unwrap();
let samples_per_buffer = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: &element,
@ -234,7 +234,7 @@ impl ObjectImpl<BaseSrc> for SineSrc {
}
Property::UInt("freq", ..) => {
let mut settings = self.settings.lock().unwrap();
let freq = value.get().unwrap();
let freq = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: &element,
@ -246,7 +246,7 @@ impl ObjectImpl<BaseSrc> for SineSrc {
}
Property::Double("volume", ..) => {
let mut settings = self.settings.lock().unwrap();
let volume = value.get().unwrap();
let volume = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: &element,
@ -258,7 +258,7 @@ impl ObjectImpl<BaseSrc> for SineSrc {
}
Property::Boolean("mute", ..) => {
let mut settings = self.settings.lock().unwrap();
let mute = value.get().unwrap();
let mute = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: &element,
@ -270,7 +270,7 @@ impl ObjectImpl<BaseSrc> for SineSrc {
}
Property::Boolean("is-live", ..) => {
let mut settings = self.settings.lock().unwrap();
let is_live = value.get().unwrap();
let is_live = value.get_some().expect("type checked upstream");
gst_info!(
self.cat,
obj: &element,
@ -340,31 +340,16 @@ impl BaseSrcImpl<BaseSrc> for SineSrc {
}
}
struct SineSrcStatic;
// The basic trait for registering the type: This returns a name for the type and registers the
// instance and class initializations functions with the type system, thus hooking everything
// together.
impl ImplTypeStatic<BaseSrc> for SineSrcStatic {
fn get_name(&self) -> &str {
"SineSrc"
}
fn new(&self, element: &BaseSrc) -> Box<BaseSrcImpl<BaseSrc>> {
SineSrc::new(element)
}
fn class_init(&self, klass: &mut BaseSrcClass) {
SineSrc::class_init(klass);
}
}
// Registers the type for our element, and then registers in GStreamer under
// the name "sinesrc" for being able to instantiate it via e.g.
// the name "rssinesrc" for being able to instantiate it via e.g.
// gst::ElementFactory::make().
pub fn register(plugin: &gst::Plugin) {
let type_ = register_type(SineSrcStatic);
gst::Element::register(plugin, "rssinesrc", 0, type_);
gst::Element::register(
Some(plugin),
"rssinesrc",
gst::Rank::None,
SineSrc::get_type(),
)
}
```
@ -1048,4 +1033,4 @@ Try the following pipeline for testing seeking. You should be able to seek the c
gst-launch-1.0 rssinesrc ! audioconvert ! monoscope ! timeoverlay ! navseek ! glimagesink
```
And with that all features are implemented in our sine wave raw audio source.
And with that all features are implemented in our sine wave raw audio source.