GStreamer Rust bindings release 0.10.0 & gst-plugin release 0.1.0

Today I’ve released version 0.10.0 of the Rust GStreamer bindings, and after a journey of more than 1½ years the first release of the GStreamer plugin writing infrastructure crate “gst-plugin”.

Check the repositories¹² of both for more details, the code and various examples.

GStreamer Bindings

Some of the changes since the 0.9.0 release were already outlined in the previous blog post, and most of the other changes were also things I found while writing GStreamer plugins. For the full changelog, take a look at the CHANGELOG.md in the repository.

Other changes include

  • I went over the whole API in the last days, added any missing things I found, simplified API as it made sense, changed functions to take Option<_> if allowed, etc.
  • Bindings for using and writing typefinders. Typefinders are the part of GStreamer that try to guess what kind of media is to be handled based on looking at the bytes. Especially writing those in Rust seems worthwhile, considering that basically all of the GIT log of the existing typefinders consists of fixes for various kinds of memory-safety problems.
  • Bindings for the Registry and PluginFeature were added, as well as fixing the relevant API that works with paths/filenames to actually work on Paths
  • Bindings for the GStreamer Net library were added, allowing to build applications that synchronize their media of the network by using PTP, NTP or a custom GStreamer protocol (for which there also exists a server). This could be used for building video-walls, systems recording the same scene from multiple cameras, etc. and provides (depending on network conditions) up to < 1ms synchronization between devices.

Generally, this is something like a “1.0” release for me now (due to depending on too many pre-1.0 crates this is not going to be 1.0 anytime soon). The basic API is all there and nicely usable now and hopefully without any bugs, the known-missing APIs are not too important for now and can easily be added at a later time when needed. At this point I don’t expect many API changes anymore.

GStreamer Plugins

The other important part of this announcement is the first release of the “gst-plugin” crate. This provides the basic infrastructure for writing GStreamer plugins and elements in Rust, without having to write any unsafe code.

I started experimenting with using Rust for this more than 1½ years ago, and while a lot of things have changed in that time, this release is a nice milestone. In the beginning there were no GStreamer bindings and I was writing everything manually, and there were also still quite a few pieces of code written in C. Nowadays everything is in Rust and using the automatically generated GStreamer bindings.

Unfortunately there is no real documentation for any of this yet, there’s only the autogenerated rustdoc documentation available from here, and various example GStreamer plugins inside the GIT repository that can be used as a starting point. And various people already wrote their GStreamer plugins in Rust based on this.

The basic idea of the API is however that everything is as Rust-y as possible. Which might not be too much due to having to map subtyping, virtual methods and the like to something reasonable in Rust, but I believe it’s nice to use now. You basically only have to implement one or more traits on your structs, and that’s it. There’s still quite some boilerplate required, but it’s far less than what would be required in C. The best example at this point might be the audioecho element.

Over the next days (or weeks?) I’m not going to write any documentation yet, but instead will write a couple of very simple, minimal elements that do basically nothing and can be used as starting points to learn how all this works together. And will write another blog post or two about the different parts of writing a GStreamer plugin and element in Rust, so that all of you can get started with that.

Let’s hope that the number of new GStreamer plugins written in C is going to decrease in the future, and maybe even new people who would’ve never done that in C, with all the footguns everywhere, can get started with writing GStreamer plugins in Rust now.

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