dailz
b4b9990efe
Add quantitative capture-to-send latency measurement so we can diagnose remaining latency sources after #24/#25 PTS fixes. Previously frame_age_p95 was always 0.0ms because the WebRTC code path never propagated capture timestamps, even though stats.rs already supported the metric. The infrastructure existed but was disconnected. Changes: - avhw.rs: Add capture_time: Instant field to CpuNv12Frame (set when PipeWire delivers frame) and EncodedH264Frame (propagated through encode thread via new last_capture_time side-channel on SwEncEncode). - state_portal.rs: Change sent_gap channel type from Sender<f64> to Sender<(f64, Option<f64>)> so WebRTC thread can send pre-computed age_ms = capture_time.elapsed() at the exact send moment (not at stats drain time, which would inflate the measurement by ~1s). - stats.rs: record_send_from_thread now accepts Option<f64> age_ms and pushes to frame_age_ms Vec when Some. After this commit: - stats: log lines show real frame_age_p95 / frame_age_max in ms - Expected range: 5-30ms (import + scale + encode + channel send) - If much higher: server pipeline has queueing issue - If low but user still sees latency: confirms bottleneck is network or browser-side (jitter buffer, decode queue) Scope notes: - Only Portal/PipeWire path is instrumented. wlr-screencopy path uses different code path (EncState, not SwEncState) and will continue to report frame_age=0.0ms. Adding wlr instrumentation is separate scope. - This is diagnostic only — does NOT change user-visible behavior. No encoding, sending, or stats output format changes. Tests: - cargo build --release: 0 new warnings (19 baseline preserved) - cargo test: 96 lib + 3 integration, 0 failed - SAFETY comments preserved verbatim - 3 files changed, +39/-10 lines Refs #20.
wl-webrtc
Wayland screen capture and encoding tool.
Prerequisites
- Rust toolchain (1.70+):
rustup default stable - FFmpeg 6.0+ dev libraries with VAAPI support:
- Arch:
pacman -S ffmpeg - Ubuntu/Debian:
apt install libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libva-dev - Fedora:
dnf install ffmpeg-devel libva-devel
- Arch:
- Wayland dev libraries:
- Arch:
pacman -S wayland-protocols - Ubuntu/Debian:
apt install libwayland-dev wayland-protocols - Fedora:
dnf install wayland-devel wayland-protocols-devel
- Arch:
- DRM dev libraries:
- Arch:
pacman -S libdrm - Ubuntu/Debian:
apt install libdrm-dev - Fedora:
dnf install libdrm-devel
- Arch:
Build
cargo build --release
Run
# Basic capture to file
wl-webrtc --output output.mp4
# With custom FPS and bitrate
wl-webrtc --output output.mp4 --fps 60 --bitrate 8000000
# Specify DRM device for hardware encoding
wl-webrtc --output output.mp4 --drm-device /dev/dri/renderD128
# Verbose mode
wl-webrtc --output output.mp4 -v
CLI Arguments
| Argument | Default | Description |
|---|---|---|
-o, --output |
(required) | Output file path (e.g., output.mp4) |
--output-name |
auto | Wayland output name to capture |
--fps |
30 | Target frames per second |
--codec |
h264 | Video codec (h264 only for MVP) |
--hw-accel |
vaapi | Hardware acceleration method |
--drm-device |
auto | DRM render device path |
--bitrate |
auto | Target bitrate in bps |
--gop-size |
auto | Group of Pictures size |
-v, --verbose |
false | Enable verbose logging |
--port |
0 | WebTransport server port (unused in MVP) |