OSPP-2025: Proposal for Audio Controls Feature in vhost-device-sound

Add proposal to extend vhost-device-sound and QEMU vhost-user-sound
pci device to support audio control operations, as defined in
VirtIO Sound 1.3

Signed-off-by: Dorinda Bassey <dbassey@redhat.com>

Author: Dorinda Bassey

ospp/OSPP-2025.md

@@ -82,3 +82,92 @@ Libraries & Tools:
 ## Project Repository
 
 https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-sound/src
+
+# Project Name
+
+Audio Controls Feature for vhost-device-sound
+
+## Project Mentor
+
+Dorinda Bassey <dbassey@redhat.com>
+
+## Project Description
+
+The virtio-sound device emulation has been evolving to provide better virtualization support for audio functionalities.
+The goal of this project is to extend the capabilities of the virtio-sound device within the [vhost-device-sound](https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-sound)
+crate by adding audio control features such as volume adjustment, muting/unmuting, and mode switching.
+
+Recent [patches](https://lore.kernel.org/all/20240423150951.41600-39-pbonzini@redhat.com/) have introduced support for audio
+controls in the Linux headers used by QEMU, and the [VirtIO sound 1.3 specification](https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html#x1-56700014)
+has now incorporated these audio controls feature.
+
+This project will focus on implementing these new features in the Rust-based vhost-device-sound crate. This new feature enhancement will
+allow a user of the guest OS to dynamically control audio settings, improving the flexibility and usability of virtualized audio devices.
+
+The audio controls support should be implemented following the [VirtIO sound 1.3 specification](https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html#x1-56700014).
+
+## Project Notes
+
+- This project should extend vhost-device-sound to support audio control operations in compliance with [VirtIO Sound 1.3 specification](https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html#x1-56700014).
+- Add Feature Negotiation support for [VIRTIO_SND_F_CTLS](https://gitlab.com/qemu-project/qemu/-/blob/master/include/standard-headers/linux/virtio_snd.h#L15)
+  to both vhost-device-sound and QEMU to ensure that control messages are only enabled if `VIRTIO_SND_F_CTLS` is successfully negotiated between the guest and host.
+- Extend the vhost-device-sound to Handle the new audio control messages from the guest.
+- Requires modifications to QEMU’s vhost-user-sound frontend to handle feature negotiation and control messages.
+- The implementation should support:
+    - Volume control (per-channel adjustments).
+    - Muting/unmuting audio streams.
+    - Switching audio output modes (e.g., speakers/headphones).
+- Extend the [PipeWire Backend](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-sound/src/audio_backends/pipewire.rs)
+  to Implement audio control features using the [pipewire-rs crate](https://gitlab.freedesktop.org/pipewire/pipewire-rs).
+- Extend the [Alsa Backend](https://github.com/rust-vmm/vhost-device/blob/main/vhost-device-sound/src/audio_backends/alsa.rs)
+  to Implement audio control features using the [alsa rust bindings](https://github.com/diwic/alsa-rs.git).
+- The implementation will be tested using QEMU as the vhost-user frontend.
+- Automated tests will be written using cargo test.
+- A possible stretch goal is contributing to rust-vmm/vhost-device by fixing existing issues.
+
+### Other contacts
+
+Matias Ezequiel Vara Larsen <mvaralar@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>
+
+## Project Difficulty
+
+Advanced (some understanding of QEMU vhost-user sound frontend device would be good to know)
+
+## Project Size
+
+180 Hours
+
+## Technical Domain Labels
+
+[Virtualization] | [Emulation] | [Vhost-user]
+
+## Programming Language Labels
+
+[Rust] | [C]
+
+## Expect Outcome
+
+1. Extended Audio Control Features in vhost-device-sound
+    - Implement support for volume adjustment, muting/unmuting, and mode switching.
+    - Ensure compliance with the [VirtIO Sound 1.3 specification](https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html#x1-56700014).
+2. Integration with QEMU
+    - Modify QEMU's vhost-user frontend to handle new audio control commands.
+3. Automated Testing
+    - Unit tests for the backend using cargo test.
+    - Verification through QEMU testing.
+4. Documentation and Upstreaming
+    - Well-documented and upstreamed code both in vhost-device and QEMU following Rust, rust-vmm and QEMU coding standards.
+
+## Project Technical Requirements
+
+Libraries & Tools:
+- vhost-device-sound crate
+- Alsa Rust bindings
+- Pipewire Rust bindings
+- QEMU for testing the vhost-user integration
+
+## Project Repositories
+
+https://github.com/rust-vmm/vhost-device/tree/main/vhost-device-sound/src
+
+https://gitlab.com/qemu-project/qemu