Add new virtio-media V4l2 stream virtual device - #2935
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Let's avoid forking emulated_camera_mplane as the first commit, it makes the second commit very hard to review. Feel free to introduce the new device in the first commit.
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The previous implementation of the send_events function used all but one descriptor because the iterator was advanced through the entire collection of descriptors. Then only one descriptor is released back. This limits the throughput for devices and makes them more susceptible to jitter due to system load. This implementation only advances the descriptor iterator by one, leaving the rest unused. Bug: 472497998 Assisted-by: Jetski:Gemini 3.5 Flash
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This adds the implementation of the v4l2_stream_proxy device, which reads from a FIFO and behaves as a virtio-media device. worker_thread_loop in v4l2_stream_proxy uses nix::poll and nix::sys::eventfd to wait for both FIFO data and control signals (Stop/BufferQueued) without busy looping or sleeping. Bug: 472497998 Assisted-by: Jetski:Gemini 3.5 Flash
This adds all of the necessary flags and configuration to launch the v4l2_stream_proxy virtual device from the cvd cli. Bug: 472497998 Assisted-by: Jetski:Gemini 3.5 Flash
Adds TestV4l2StreamProxyCompliance to e2e tests, which: 1. Creates a FIFO on the host. 2. Starts a goroutine to write dummy YUV420M frames to the FIFO. 3. Launches CVD with v4l2_stream_proxy pointing to the FIFO. 4. Finds the video node in the guest. 5. Runs v4l2-compliance on the guest. Bug: 472497998 Assisted-by: Jetski:Gemini 3.5 Flash
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This PR introduces the
v4l2_streamdevice, avhost-user-mediabackend that enables streaming video from a host-side source (via a FIFO/named pipe) into a guest VM using thevirtio-mediaprotocol.It allows video data generated on the host (e.g., from a video file, synthetic test source, or any other producer of raw video frames) to be streamed directly into the guest VM's V4L2 framework.
The first commit copies over the
emulated_camera_mplanecrate into the newv4l2_streamcrate, and includes minimal changes to get it building and launchable. The second commit modifies the new crate with the new functionality.b/472497998