BUG-2 (HIGH): SHM Buffer event caused permanent hang
In the ZwlrScreencopyFrameV1 dispatcher, receiving a SHM Buffer event
left in_flight_surface stuck at AllocQueued forever, preventing
queue_alloc_frame() from requesting new frames.
Fix: treat Buffer as a metadata offer (v3 protocol), wait for
BufferDone to decide failure, and add AllocQueued state guard to
LinuxDmabuf handler.
BUG-3 (MEDIUM): Portal backend picked wrong GPU on multi-GPU systems
state_portal.rs hardcoded /dev/dri/renderD128 then renderD129, which
selects the wrong GPU when PipeWire uses a different device.
Fix: extract find_drm_render_nodes() as shared utility; defer DRM
device selection to first PipeWire frame; test each candidate with
av_hwframe_transfer_data to find the GPU that can actually import
the DMA-BUF frame.
BUG-4 (LOW): VAAPI device context created twice unnecessarily
try_finalize_output() created an AvHwDevCtx stored in EverythingButFmt,
but negotiate_format() discarded it (_hw_device_ctx) and EncState::new
created a new one.
Fix: thread the existing hw_device_ctx through negotiate_format() and
create_encoder() to EncState::new() which reuses it when provided.
Add comprehensive Chinese documentation comments to cap_portal,
main, and state_portal modules covering architecture, lifecycle,
and data flow for each component.
PipeWire spa_meta_header.pts is CLOCK_MONOTONIC in nanoseconds, but the
encoder expects frame-number units (time_base = 1/fps). The raw nanosecond
value was assigned directly to AVFrame.pts, causing the encoder/muxer to
interpret timestamps as billions of frames, producing corrupted duration
metadata and broken rate control.
Fix: record the first frame's PTS as a nanosecond base, compute elapsed
nanoseconds for each subsequent frame, then convert to frame numbers via
elapsed_ns * fps / 1_000_000_000. Using elapsed time avoids i64 overflow
on absolute timestamps (~10^18 ns).
Matches the WLR path pattern (state.rs:525-527) which converts microseconds
to frame numbers for the same encoder.
Add a second capture backend for compositors without wlr-screencopy
(KWin, GNOME, etc.) using the xdg-desktop-portal ScreenCast interface
and PipeWire DMA-BUF streaming.
New files:
- src/backend_detect.rs: auto-detect wlr-screencopy vs portal backend
- src/cap_portal.rs: Portal session setup + PipeWire DMA-BUF thread
- src/state_portal.rs: StatePortal encoder pipeline (DMA-BUF → VAAPI)
Changes:
- Cargo.toml: add ashpd 0.13, tokio 1, pipewire 0.9, libspa 0.9,
crossbeam-channel 0.5
- src/args.rs: add --backend CLI flag
- src/avhw.rs: extract create_encoder() from inline State code
- src/main.rs: route to portal or wlr-screencopy based on backend
- src/state.rs: fix params.destroy() on dup failure, cleanup
in_flight_surface on copy fail, use create_encoder()
- tests/integration_test.rs: add --backend flag tests
