PipeWire implementation

[midoriiro]

PipeWire implementation based on pipewire/pipewire-rs/doc and others draft PRs in this repository (thanks to them).

There is two additional crates, one for the PW client and one for SPA utils (used for some POD deserialization).

Client capabilities:

• Retrieve all Audio/(Sink/Source) nodes
  • Thats include default audio nodes (defined by your session manager)
  • Format information (sample rate, sample format, channels)
• Retrieve metadata for global settings and default audio nodes (provided by session manager, AKA WirePlumber)
• Create and manage stream
• Create virtual node

I updated some CPAL examples (enumerate and beep).

TODO (just some ideas):

• Duplex audio node:
  • Can be useful as a "loopback" device. In CPAL that mean input stream can be retrieved, updated and injected in output stream. Need a POC, I'm just supposing.
• Updating Port/Link of an audio node: Use case, a virtual node is a DSP (EQ, Reverb, ...), clients nodes (Spotify, browser, ...), audio node (sound card playback). DSP node will be inserted between clients nodes and audio node, with all ports/links remapped correctly.
  • Or simple use case: create a virtual node and plug it to an audio node monitor ports
• Subscribe to node/stream events/listeners: stream format or parameters changed, same for node.
• Improve test coverage and create some integration test
  • Use TestContainer to test different cases with embed PipeWire and session manager installed in a container image
• Improve documentation (README.md to explain client initialization flow, post initialization flow, how to handle PW object creation)
• Improve client API: currently PipewireClient is just a struct with a bunch of function that send requests. I would like to create different structs to separate concern and improve readability/maintainability (struct API for node, struct API for stream, etc)
• Improve quality code in general, clean some code, keep coherence in different parts on code base

I'm posting this PR as draft for now, if you have any suggestion/feedback or particular use cases, I'm glad to discuss it.

Note: You will need to install PipeWire development lib from your package manager. Having WirePlumber or PipeWire Media Session running. If your PW socket is located somewhere else you can define env vars:

• (socket name): PIPEWIRE_REMOTE
• (socket location): PIPEWIRE_RUNTIME_DIR or XDG_RUNTIME_DIR

[midoriiro]

I guess I'll move this client to a separate repository, this PR became prettry huge héhé.

[est31]

Hi and thank you for this pull request. PipeWire is certainly the future and therefore this PR is very valuable.

Sadly, the time that I can dedicate to cpal and my free time OSS endeavours is very limited as of late. So I can't really review this PR in its depth. I glanced over the code and it doesn't look bad.

Would you be interested in me merging this and then the community figures out if there is issues/bugs? If you have the time to spare, I can make you a maintainer.

[midoriiro]

Hi thanks for your feedback, indeed this a huge PR. I'm still working on it but on my own repository at this moment, I was planning to return to this PR to include only the PipeWire integration into CPAL.

I don't mind if you merge it now, that could be cool to have feedbacks. But I was thinking if this Pipewire client implementation could have it own repository under RustAudio organization. What do you think ? Either way, I would be glad to maintain it.

[colinmarc]

I'll just note here that my PR #957 has some overlap with this, since PipeWire has first-class support for the PulseAudio protocol. I don't have a preference for how that overlap gets resolved.

(I didn't see this until after I opened #957.)

[midoriiro]

I'll just note here that my PR #957 has some overlap with this, since PipeWire has first-class support for the PulseAudio protocol. I don't have a preference for how that overlap gets resolved.

(I didn't see this until after I opened #957.)

Good question, if by overlap you mean about merge conflicts that will depend on which PR will be merged first. I need to do some rework before this PR will be merged.

If you mean overlap between PulseAudio integration and PipeWire integration. I guess if you have a PipeWire server running on your system, you could use CPAL PulseAudio integration to connect to the PipeWire server through their pipewire-pulse daemon.

I don't have any knowledge about how PA is working but to integrate PW to CPAL I needed to create an init phase to retrieve default configuration (sample rate, etc) and default devices configured by the session manager (WirePlumber). That could be interesting to know how your PA implementation behave when connected to pipewire-pulse daemon.

If think the two implementations can coexists. If tomorrow I'm going to switch to Archlinux and setup a PA server, I'll be glad to find a PA integration into CPAL.