gamescope only offers LINEAR dmabufs, which the EGL/GL interop path can't handle (NVIDIA's
EGL lists no LINEAR modifier for sampling). Attempt a direct CUDA external-memory import
(cuImportExternalMemory OPAQUE_FD, cached per buffer fd, one DtoD copy per frame into the
pooled buffer): the FFI + plumbing are in place, and LINEAR(0) is now advertised alongside
the tiled EGL modifiers (tiled first, so KWin still prefers it — regression-tested).
Empirically the 595 desktop driver rejects raw dmabuf fds as OPAQUE_FD (CUDA_ERROR_UNKNOWN),
matching the documented limitation — true LINEAR GPU import needs a Vulkan interop bridge
(import dmabuf via VK_EXT_external_memory_dma_buf, GPU-copy into an exportable allocation,
hand that to CUDA), noted as future work. So the importer now degrades instead of dying:
on GPU-import failure it logs once, disables itself, and falls through to the CPU mmap path.
Validated: gamescope + LUMEN_ZEROCOPY=1 runs full-rate (122.9 fps @720p120, valid HEVC) via
the fallback; KWin keeps real zero-copy.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Deep investigation (gdb + daemon traces) proved the gamescope capture stall is a gamescope
3.16.20 bug, not ours: it calls pw_loop_iterate() without pw_loop_enter()/leave(), and under
PipeWire 1.6's loop locking its main thread permanently holds the loop mutex — the pw thread
deadlocks, gamescope never acks the daemon's port_set_param(Format), and the link parks in
"negotiating" silently. Stock gst pipewiresrc fails identically. Fixed upstream by gamescope
commit e3ed1ea7 ("pipewire: Fix pipewire loop locking", pipewire#5148); first release 3.16.22.
Ubuntu 26.04 ships 3.16.20 (built ten days before the fix) — patch/upgrade required.
Consumer-side improvements from the investigation (all verified correct vs gamescope's pods,
and needed once the producer is fixed):
- discover the node from gamescope's own "stream available on node ID: N" log line (its
node.name appears on two objects; the advertised id is authoritative); pw-dump fallback
- CPU path accepts mappable dmabufs: Buffers param now offers MemPtr|MemFd|DmaBuf (gamescope
counter-offers exactly DmaBuf when its modifier pod wins, never MemPtr), mmap the fd
ourselves when MAP_BUFFERS didn't (Vulkan-exported dmabufs aren't flagged mappable), and
treat chunk.size==0 as the computed span
- warn_once on every silent frame-drop path in the process callback
- node.dont-reconnect on our capture streams: an orphaned stream re-targeted by wireplumber
onto a fresh node wedges it — and a stuck link head-blocks the daemon's shared work queue,
stalling ALL new link negotiation system-wide (this poisoned whole test sessions)
- LUMEN_GAMESCOPE_NODE (attach to an existing gamescope) + LUMEN_PW_FIXED_POD (negotiation
bisection) debug knobs
KWin path regression-tested (zero-copy intact). gamescope end-to-end validation pending the
patched gamescope build.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Honor the client's requested resolution by rendering a compositor virtual output at
exactly that size — native, headless, no scaling. There is no cross-compositor Wayland
protocol for this, so it's a per-compositor backend behind the (previously stubbed)
VirtualDisplay trait.
- vdisplay.rs: VirtualDisplay::create(mode) now returns a live VirtualOutput
{ node_id, remote_fd: Option<OwnedFd>, keepalive } with RAII teardown (drop releases
the output) instead of an inert OutputHandle + explicit destroy. Add compositor
detect() (LUMEN_COMPOSITOR / XDG_CURRENT_DESKTOP).
- vdisplay/kwin.rs: the KWin backend — the zkde_screencast_unstable_v1 stream_virtual_output
client (vendored protocol XML + wayland-scanner codegen). Creates a WxH output, returns
its PipeWire node (default daemon, remote_fd=None); a keepalive thread holds the Wayland
connection until dropped. (Moved here from capture/kwin.rs — it's a vdisplay backend, not
capture.)
- capture: generalize the PipeWire consumer to Option<OwnedFd> (portal remote vs. default
daemon) and add capture_virtual_output(vout), compositor-agnostic, owning the keepalive.
- gamestream/stream.rs: LUMEN_VIDEO_SOURCE=virtual creates a virtual display sized to the
client's cfg and captures it (self-contained, not pooled — a reconnect at a new
resolution gets a fresh output).
- m0: --source kwin-virtual goes through the trait.
Verified end-to-end against the running headless KWin: the request reaches the compositor
and is handled cleanly. Native creation needs a backend implementing createVirtualOutput —
the DRM backend, or the VirtualBackend since KWin 6.5.6; on this box's --virtual 6.4.5 it
returns "Could not find output" (expected; validates after the KWin upgrade). wlroots/Mutter
backends are the next ones to land on the same seam.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The PipeWire dmabuf now reaches NVENC with no CPU touch. Verified live against
headless KWin: a tiled BGRx dmabuf is imported and encoded to a pixel-correct
H.265 stream (decoded frame matches the captured desktop — no tiling artifacts,
no colour swap). The CPU-copy path stays the default and the runtime fallback.
Capture side (zerocopy::egl): desktop NVIDIA can't register a dmabuf EGLImage
with CUDA directly (cuGraphicsEGLRegisterImage is Tegra-only; cuGraphicsGLRegisterImage
rejects EGLImage-backed textures), so we follow OBS/Sunshine — bind the EGLImage
to a GL texture, render it through a fullscreen-triangle shader into an immutable
GL_RGBA8 texture (de-tiling + .bgra swizzle to the BGRx the encoder wants), then
register that texture with CUDA and copy it device-to-device into an owned buffer
so the dmabuf returns to the compositor immediately.
Encode side (encode/linux::submit_cuda): take a *pooled* CUDA surface via
av_hwframe_get_buffer and device→device-copy our imported buffer into it, instead
of wrapping our own pointer in a bare AVFrame. A bare frame is rejected with
EINVAL (NVENC ignores frames with null buf[0]; the encode path's av_frame_ref
needs a refcounted buffer), and a fresh device pointer every frame would thrash
NVENC's bounded resource-registration cache — the pool recycles a small set.
Also: gate FFmpeg AV_LOG_DEBUG behind LUMEN_FFMPEG_DEBUG for diagnosing
hw-frame rejects, and refresh the now-accurate module docs.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Wire the capture side of zero-copy (LUMEN_ZEROCOPY=1):
- EGL importer now opens the headless EGLDisplay on the NVIDIA EGL device
(EGL_PLATFORM_DEVICE_EXT) and queries its importable DRM modifiers
(eglQueryDmaBufModifiersEXT).
- The PipeWire stream advertises a BGRx dmabuf format with those modifiers as a
mandatory enum Choice + a dmabuf-only Buffers param; the compositor fixates an
importable tiled modifier. param_changed reads the negotiated modifier; the
process callback imports the dmabuf (eglCreateImage with explicit LO/HI
modifier) and would copy it into a CUDA buffer for the encoder.
Validated against headless KWin (Plasma 6.4): negotiation succeeds (13 NVIDIA
modifiers advertised, KWin fixates one, stream reaches Streaming with a real
tiled dmabuf) and `eglCreateImage` succeeds. The remaining blocker is
`cuGraphicsEGLRegisterImage` returning CUDA_ERROR_INVALID_VALUE on the
dmabuf-imported EGLImage — the likely fix is to bind the EGLImage to a GL
texture (glEGLImageTargetTexture2DOES) and register that via
cuGraphicsGLRegisterImage (OBS/Sunshine's path), which needs a GL context.
The CPU-copy path stays the default and is unaffected (regression-checked: real
KWin capture → HEVC). LUMEN_ZEROCOPY is opt-in/experimental until the CUDA
registration lands.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Scaffolding for dmabuf zero-copy (plan §9), opt-in via LUMEN_ZEROCOPY:
- src/zerocopy/{cuda,egl}.rs: hand-rolled CUDA Driver-API FFI (no Rust crate
exposes the EGL-interop calls / CUeglFrame) with a shared process-wide
CUcontext + pitched device buffers; an EGL importer (GBM platform on the
NVIDIA render node) that turns a dmabuf into an EGLImage, registers it with
CUDA, and copies it device-to-device into an owned buffer. `zerocopy-probe`
subcommand validates the FFI/linking/GPU access — confirmed on the box
(driver 595, EGL_EXT_image_dma_buf_import + modifiers).
- CapturedFrame gains a FramePayload enum (Cpu(Vec<u8>) | Cuda(DeviceBuffer));
the encoder branches: CPU keeps the expand+upload path, CUDA wraps the device
buffer in an AV_PIX_FMT_CUDA frame fed straight to hevc_nvenc (sharing our
CUcontext via a hand-declared AVCUDADeviceContext, since ffmpeg-sys doesn't
bind hwcontext_cuda.h). open_video/the encoder take a `cuda` flag derived from
the first frame's payload.
The capture-side dmabuf negotiation (which produces the Cuda frames) is the
next step; the CPU path is unchanged and remains the default + fallback. Builds
clean, clippy clean, tests pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
On RemoteDesktop-capable desktops (KWin, GNOME), select the ScreenCast source on
a session created via the RemoteDesktop portal and start it through RemoteDesktop,
so a single grant — pre-authorized headlessly via the `kde-authorized` permission,
exactly like the libei input path — also covers screen capture. Standalone
ScreenCast has no such bypass and would raise an un-clickable dialog on a headless
box. wlroots/Sway has no RemoteDesktop portal, so it keeps the plain ScreenCast
session; the choice keys off inject::default_backend(). The PipeWire consumer is
unchanged — the anchored session yields the same fd + node id.
Validated on headless KWin (Plasma 6.4): the portal grants the session with no
dialog and PipeWire negotiates the format (1920x1080 BGRx, Streaming). Frame
delivery on KWin still pends dmabuf import — KWin hands GPU dmabuf buffers and the
M0 consumer is CPU-copy/shm only (plan §9, zero-copy) — so it's the next step;
the CPU-copy path remains correct on wlroots.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Disconnect/reconnect now works reliably. Previously each stream spawned its own
portal+PipeWire (and PipeWire audio) capture threads and never stopped them, so a
reconnect opened a SECOND screencast session that conflicted with the leaked
first one ("no PipeWire frame within 10s" → black screen on reconnect).
- The screen capturer and audio capturer are now persistent, held in AppState and
reused across streams (created on the first stream). One screencast session for
the host's lifetime → no conflict, and instant reconnect (no re-handshake).
Verified live: 3 stream cycles, 1 create + 2 "reusing capturer", clean every time.
- Capturer::set_active gates the (5K, ~1.3 GB/s) de-pad copy to active streams, so
the persistent video capturer is nearly free while idle between streams.
- AudioCapturer::drain discards buffered chunks on reuse so the client never hears
stale audio captured while idle.
- stream.rs / gamestream/audio.rs split into a borrow-the-capturer wrapper + the
encode/send body, so the capturer is always returned to its slot on exit.
This holds whether the client reconnects via /resume (Moonlight's "running →
play/continue") or a fresh /launch — both re-run RTSP PLAY → a new stream cycle.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
A stock Moonlight client now gets video + full input + AUDIO from the
from-scratch GameStream host (verified live end-to-end on a macOS client).
Audio (audio.rs, audio/linux.rs, gamestream/audio.rs):
- Capture the default PipeWire sink's monitor (system output) as interleaved
f32 stereo @ 48kHz via stream.capture.sink, on its own thread.
- Opus-encode 5ms/240-sample stereo frames (RESTRICTED_LOWDELAY, CBR) and send
as GameStream RTP audio: 12-byte BE RTP_PACKET (packetType 97, seq+1/pkt,
timestamp += packetDuration, ssrc 0) on UDP 48000, after learning the client
endpoint from its port-learning ping.
- Encrypt the Opus payload with AES-128-CBC (PKCS7), key = launch rikey, IV =
BE32(rikeyid + seq) in [0..4]. Like the control stream, modern Moonlight
always decrypts audio regardless of the negotiated flags — plaintext makes it
log "Failed to decrypt audio packet" and play silence (diagnosed from the
client log). RTP header stays in the clear. Scheme cross-checked against
Sunshine stream.cpp/crypto.cpp + moonlight AudioStream.c.
- Pace each frame to its 5ms slot (PipeWire delivers ~1024-frame buffers) to
avoid bursts the client's jitter buffer hears as glitches. LUMEN_AUDIO_GAIN
applies optional linear gain for quiet sources.
- DESCRIBE SDP advertises the stereo Opus config (a=fmtp:97 surround-params).
Video (stream.rs): pace at a steady ≤60fps, re-encoding the last captured frame
when the compositor produces none. wlroots only emits on damage, so a static or
slow-updating desktop previously starved the client into a "network too slow"
abort; an unchanged frame costs a near-empty P-frame. Adds a non-blocking
Capturer::try_latest (portal drains to the freshest queued frame).
Misc: serialize pipewire init across the video + audio capture threads
(pwinit.rs, std::sync::Once) to avoid a concurrent pw_init race. Deps: opus,
cbc; libopus-dev in bootstrap-ubuntu.sh.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler