perf(portal): achieve 58-60fps PipeWire screen capture

- Force PipeWire quantum=512 via NODE_FORCE_QUANTUM (48000/512=93Hz scheduling)
- Switch to libx264 ultrafast/zerolatency with 6 threads
- Use two-phase poll_and_encode: blocking recv_timeout for first frame,
  non-blocking try_recv drain for subsequent frames
- Remove fps_limit from portal path (PW already rate-limits via quantum/KWin;
  fps_limit's min_interval was silently dropping ~10% of valid frames)
- Remove diagnostic instrumentation (TIMING/PIPEWIRE logs, timing fields,
  pw_stats counters)
- Add lightweight production stats: per-10s fps log + shutdown summary
- Prefer libx264 over libopenh264 (better quality at same speed)

src/cap_portal.rs

@@ -13,6 +13,7 @@
 
 use std::os::fd::{AsRawFd, FromRawFd, OwnedFd};
 use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::Arc;
 use std::thread::{self, JoinHandle};
 
 use anyhow::Result;
@@ -80,13 +81,10 @@ pub struct CapPortal {
 struct PwThreadCtx {
     frame_tx: Sender<PwDmaBufFrame>,
     event_tx: Sender<PwCtrlEvent>,
-    dropped: AtomicU64,
+    dropped: Arc<AtomicU64>,
     shutdown_read: OwnedFd,
-    /// Portal 返回的 PipeWire 远程连接文件描述符
     pw_fd: OwnedFd,
-    /// Portal 返回的 PipeWire 节点 ID，标识要捕获的屏幕流
     node_id: u32,
-    /// 目标帧率（当前保留，未直接用于 PipeWire 协商）
     fps: u32,
 }
 
@@ -96,7 +94,7 @@ impl CapPortal {
     /// 执行流程:
     ///   1. 创建 Tokio 运行时（用于异步 Portal 调用）
     ///   2. 通过 XDG Desktop Portal 请求屏幕录制权限，获取 PipeWire fd 和 node_id
-    ///   3. 创建有界通道（容量 3）用于帧传递
+    ///   3. 创建有界通道（容量 16）用于帧传递
     ///   4. 创建 eventfd 对，用于线程安全的关闭信号传递
     ///   5. 启动 PipeWire 捕获线程
     pub fn new(args: &Args) -> Result<Self> {
@@ -107,7 +105,7 @@ impl CapPortal {
         // block_on 在此处同步等待异步 Portal 调用完成
         let (pw_fd, node_id) = rt.block_on(async { Self::setup_portal().await })?;
 
-        let (frame_tx, frame_rx) = bounded(3);
+        let (frame_tx, frame_rx) = bounded(16);
         let (event_tx, event_rx) = bounded(8);
 
         let efd = unsafe { libc::eventfd(0, libc::EFD_CLOEXEC | libc::EFD_NONBLOCK) };
@@ -124,10 +122,12 @@ impl CapPortal {
             return Err(anyhow::anyhow!("dup eventfd failed: {err}"));
         }
 
+        let pw_dropped = Arc::new(AtomicU64::new(0));
+
         let ctx = PwThreadCtx {
             frame_tx,
             event_tx,
-            dropped: AtomicU64::new(0),
+            dropped: pw_dropped.clone(),
             shutdown_read: unsafe { OwnedFd::from_raw_fd(efd) },
             pw_fd,
             node_id,
@@ -305,7 +305,7 @@ fn pipewire_thread(ctx: PwThreadCtx) {
         shutdown_read,
         pw_fd,
         node_id,
-        fps: _fps,
+        fps,
     } = ctx;
 
     let mainloop = match pw::main_loop::MainLoopBox::new(None) {
@@ -344,6 +344,7 @@ fn pipewire_thread(ctx: PwThreadCtx) {
             *pw::keys::MEDIA_TYPE => "Video",
             *pw::keys::MEDIA_CATEGORY => "Capture",
             *pw::keys::MEDIA_ROLE => "Screen",
+            *pw::keys::NODE_FORCE_QUANTUM => "512",
         },
     ) {
         Ok(s) => s,
@@ -359,9 +360,13 @@ fn pipewire_thread(ctx: PwThreadCtx) {
     let _listener = stream
         .add_local_listener::<()>()
         .state_changed(move |_, _, old, new| {
-            tracing::debug!("PipeWire stream state: {old:?} -> {new:?}");
+            tracing::info!("PipeWire stream state: {old:?} -> {new:?}");
             match new {
-                pw::stream::StreamState::Error(_) | pw::stream::StreamState::Unconnected => {
+                pw::stream::StreamState::Error(e) => {
+                    tracing::error!("PipeWire stream error: {e}");
+                    let _ = event_tx_state.try_send(PwCtrlEvent::StreamEnded);
+                }
+                pw::stream::StreamState::Unconnected => {
                     let _ = event_tx_state.try_send(PwCtrlEvent::StreamEnded);
                 }
                 _ => {}
@@ -390,11 +395,16 @@ fn pipewire_thread(ctx: PwThreadCtx) {
                 let drm_format = spa_to_drm_fourcc(info.format());
                 // 获取 DRM 修饰符，描述 GPU buffer 的内存布局（如 tiling 模式）
                 let modifier = info.modifier();
+                let framerate = info.framerate();
+                let max_framerate = info.max_framerate();
                 // 保存协商后的格式信息，供 process 回调读取
                 format_info.set(Some((width, height, drm_format, modifier)));
                 tracing::info!(
                     "PipeWire format negotiated: {width}x{height}, \
-                     drm_format={drm_format:#010x}, modifier={modifier:#x}"
+                     drm_format={drm_format:#010x}, modifier={modifier:#x}, \
+                     framerate={}/{}, max_framerate={}/{}",
+                    framerate.num, framerate.denom,
+                    max_framerate.num, max_framerate.denom,
                 );
             }
         })
@@ -405,15 +415,8 @@ fn pipewire_thread(ctx: PwThreadCtx) {
             let format_info = format_info.clone();
             let frame_tx = frame_tx.clone();
             let dropped = dropped;
-            let process_count = Rc::new(Cell::new(0u64));
-            let process_count_clone = process_count.clone();
             move |stream, _| {
-                let count = process_count_clone.get() + 1;
-                process_count_clone.set(count);
-                if count <= 5 || count % 60 == 0 {
-                    tracing::info!("PipeWire process callback #{count}");
-                }
-                // 从流中出队原始 buffer（包含帧数据的元信息）
+
                 let raw_buf = unsafe { stream.dequeue_raw_buffer() };
                 if raw_buf.is_null() {
                     return;
@@ -519,13 +522,8 @@ fn pipewire_thread(ctx: PwThreadCtx) {
         })
         .register();
 
-    // 空的参数数组，不主动请求特定格式（由 PipeWire 和源端协商决定）
     let mut params: [&pw::spa::pod::Pod; 0] = [];
 
-    // 连接到指定的 PipeWire 节点
-    // Direction::Input: 作为消费者（输入方向接收数据）
-    // AUTOCONNECT: 允许 PipeWire 自动连接源和消费者
-    // MAP_BUFFERS: 映射 buffer 到用户空间（DMA-BUF 模式下必须设置）
     if let Err(e) = stream.connect(
         pw::spa::utils::Direction::Input,
         Some(node_id),