fix(webrtc): SO_SNDBUF 2MB + VBV rate limiting + stats integration

P0 - UDP send buffer: set SO_SNDBUF=2MB to prevent EAGAIN on large IDR
frames (218KB/256KB keyframes caused 18+ EAGAIN bursts). Actual Linux
buffer 4096KB confirmed.

P1 - VBV rate limiting: cap rc_max_rate=bitrate and rc_buffer_size=
bitrate/4 for WebRTC encode path, preventing oversized IDR frames.

Stats: integrate PipelineStats into cap_portal (dropped_count), state.rs
(wlroots path), webrtc.rs (browser getStats enhancement + stats panel).

src/cap_portal.rs

@@ -73,6 +73,7 @@ pub struct CapPortal {
     event_rx: Receiver<PwCtrlEvent>,
     pw_thread: Option<JoinHandle<()>>,
     rt: Runtime,
+    pw_dropped: Arc<AtomicU64>,
 }
 
 /// PipeWire 捕获线程的上下文数据
@@ -149,6 +150,7 @@ impl CapPortal {
             event_rx,
             pw_thread: Some(pw_thread),
             rt,
+            pw_dropped,
         })
     }
 
@@ -160,6 +162,16 @@ impl CapPortal {
         &self.event_rx
     }
 
+    /// Returns the total number of PipeWire frames dropped due to channel backlog.
+    pub fn dropped_count(&self) -> u64 {
+        self.pw_dropped.load(Ordering::Relaxed)
+    }
+
+    /// Returns the number of frames currently waiting in the capture channel.
+    pub fn capture_queue_depth(&self) -> usize {
+        self.frame_rx.len()
+    }
+
     /// 通过 XDG Desktop Portal 建立屏幕录制会话
     ///
     /// 与桌面环境的 D-Bus 服务交互，请求用户授权屏幕录制。
@@ -476,7 +488,9 @@ fn pipewire_thread(ctx: PwThreadCtx) {
     let mainloop = match pw::main_loop::MainLoopBox::new(None) {
         Ok(ml) => ml,
         Err(e) => {
-            let _ = event_tx.try_send(PwCtrlEvent::Error(format!("MainLoop::new failed: {e}")));
+            if let Err(e) = event_tx.try_send(PwCtrlEvent::Error(format!("MainLoop::new failed: {e}"))) {
+                tracing::error!("MainLoop::new failed and error channel also failed: {e}");
+            }
             return;
         }
     };
@@ -484,7 +498,9 @@ fn pipewire_thread(ctx: PwThreadCtx) {
     let context = match pw::context::ContextBox::new(mainloop.loop_(), None) {
         Ok(c) => c,
         Err(e) => {
-            let _ = event_tx.try_send(PwCtrlEvent::Error(format!("Context::new failed: {e}")));
+            if let Err(e) = event_tx.try_send(PwCtrlEvent::Error(format!("Context::new failed: {e}"))) {
+                tracing::error!("Context::new failed and error channel also failed: {e}");
+            }
             return;
         }
     };
@@ -492,7 +508,9 @@ fn pipewire_thread(ctx: PwThreadCtx) {
     let core = match context.connect_fd(pw_fd, None) {
         Ok(c) => c,
         Err(e) => {
-            let _ = event_tx.try_send(PwCtrlEvent::Error(format!("connect_fd failed: {e}")));
+            if let Err(e) = event_tx.try_send(PwCtrlEvent::Error(format!("connect_fd failed: {e}"))) {
+                tracing::error!("connect_fd failed and error channel also failed: {e}");
+            }
             return;
         }
     };
@@ -514,7 +532,9 @@ fn pipewire_thread(ctx: PwThreadCtx) {
     ) {
         Ok(s) => s,
         Err(e) => {
-            let _ = event_tx.try_send(PwCtrlEvent::Error(format!("Stream::new failed: {e}")));
+            if let Err(e) = event_tx.try_send(PwCtrlEvent::Error(format!("Stream::new failed: {e}"))) {
+                tracing::error!("Stream::new failed and error channel also failed: {e}");
+            }
             return;
         }
     };
@@ -584,12 +604,14 @@ fn pipewire_thread(ctx: PwThreadCtx) {
 
                 let raw_buf = unsafe { stream.dequeue_raw_buffer() };
                 if raw_buf.is_null() {
+                    tracing::trace!("process: null raw_buf");
                     return;
                 }
 
                 // 获取 SPA buffer 结构体，包含数据数组、元数据等
                 let spa_buf = unsafe { (*raw_buf).buffer };
                 if spa_buf.is_null() {
+                    tracing::trace!("process: null spa_buf");
                     unsafe { stream.queue_raw_buffer(raw_buf) };
                     return;
                 }
@@ -599,6 +621,7 @@ fn pipewire_thread(ctx: PwThreadCtx) {
                 let n_datas = unsafe { (*spa_buf).n_datas };
                 let datas_ptr = unsafe { (*spa_buf).datas };
                 if n_datas == 0 || datas_ptr.is_null() {
+                    tracing::trace!("process: no data (n_datas={n_datas})");
                     unsafe { stream.queue_raw_buffer(raw_buf) };
                     return;
                 }
@@ -609,11 +632,13 @@ fn pipewire_thread(ctx: PwThreadCtx) {
                     unsafe { &*(datas_ptr as *const pw::spa::buffer::Data) };
                 let fd = data_ref.fd();
                 if fd < 0 {
+                    tracing::trace!("process: invalid fd={fd}");
                     unsafe { stream.queue_raw_buffer(raw_buf) };
                     return;
                 }
 
                 if data_ref.as_raw().chunk.is_null() {
+                    tracing::trace!("process: null chunk");
                     unsafe { stream.queue_raw_buffer(raw_buf) };
                     return;
                 }
@@ -651,6 +676,7 @@ fn pipewire_thread(ctx: PwThreadCtx) {
                     return;
                 };
                 if width == 0 || height == 0 || format == 0 {
+                    tracing::trace!("process: invalid dimensions {width}x{height} format={format}");
                     unsafe { stream.queue_raw_buffer(raw_buf) };
                     return;
                 }
@@ -695,7 +721,9 @@ fn pipewire_thread(ctx: PwThreadCtx) {
         StreamFlags::AUTOCONNECT | StreamFlags::MAP_BUFFERS,
         &mut params,
     ) {
-        let _ = event_tx.try_send(PwCtrlEvent::Error(format!("stream.connect failed: {e}")));
+        if let Err(e) = event_tx.try_send(PwCtrlEvent::Error(format!("stream.connect failed: {e}"))) {
+            tracing::error!("stream.connect failed and error channel also failed: {e}");
+        }
         return;
     }
 

src/state.rs

@@ -46,6 +46,7 @@ use crate::args::Args;
 use crate::avhw::{AvHwDevCtx, EncState, SwEncState};
 use crate::cap_wlr_screencopy::CapWlrScreencopy;
 use crate::fps_limit::FpsLimit;
+use crate::stats::{FrameTimings, PipelineStats};
 use crate::transform::{transpose_if_transform_transposed, Transform};
 use crate::webrtc::WebRtcState;
 
@@ -213,6 +214,9 @@ pub struct State<S: CaptureSource> {
     pub stage: EncConstructionStage<S>,
     pub in_flight_surface: InFlightSurface<S>,
     pub starting_timestamp: Option<i64>,
+    pub stats_start_time: Option<Instant>,
+    pub stats_last_time: Option<Instant>,
+    pub stats_frames: u64,
     pub first_frame: bool,
     pub args: Args,
     pub errored: bool,
@@ -226,6 +230,7 @@ pub struct State<S: CaptureSource> {
     webrtc_rx: Option<crossbeam_channel::Receiver<Vec<u8>>>,
     webrtc_frames_sent: u64,
     webrtc_paused: Option<Arc<AtomicBool>>,
+    stats: PipelineStats,
 }
 
 // ---------------------------------------------------------------------------
@@ -302,6 +307,9 @@ impl<S: CaptureSource> State<S> {
             },
             in_flight_surface: InFlightSurface::None,
             starting_timestamp: None,
+            stats_start_time: None,
+            stats_last_time: None,
+            stats_frames: 0,
             first_frame: true,
             fps_limit: FpsLimit::new(fps),
             args,
@@ -315,6 +323,7 @@ impl<S: CaptureSource> State<S> {
             webrtc_rx,
             webrtc_frames_sent: 0,
             webrtc_paused,
+            stats: PipelineStats::new(),
         };
 
         // registry_queue_init consumes registry events internally during its
@@ -492,7 +501,7 @@ impl<S: CaptureSource> State<S> {
         // is a freshly allocated empty Video frame.
         let ret = unsafe { ffi::av_hwframe_get_buffer(frames_rgb_ctx, surface.as_mut_ptr(), 0) };
         if ret < 0 {
-            tracing::error!("av_hwframe_get_buffer failed: error {}", ret);
+            tracing::error!("av_hwframe_get_buffer failed: {}", crate::avhw::ff_err(ret));
             self.errored = true;
             return;
         }
@@ -505,7 +514,7 @@ impl<S: CaptureSource> State<S> {
         }
         let ret = unsafe { ffi::av_hwframe_map(map_frame.as_mut_ptr(), surface.as_ptr(), 0) };
         if ret < 0 {
-            tracing::error!("av_hwframe_map failed: error {}", ret);
+            tracing::error!("av_hwframe_map failed: {}", crate::avhw::ff_err(ret));
             self.errored = true;
             return;
         }
@@ -530,7 +539,7 @@ impl<S: CaptureSource> State<S> {
                 // takes ownership of the fd, and the original fd is owned by map_frame.
                 let fd_dup = unsafe { libc::dup(obj.fd) };
                 if fd_dup < 0 {
-                    tracing::error!("failed to dup dma-buf fd");
+                    tracing::error!("failed to dup dma-buf fd: {}", std::io::Error::last_os_error());
                     // wayland-client does not auto-destroy params on Drop.
                     params.destroy();
                     self.errored = true;
@@ -574,6 +583,8 @@ impl<S: CaptureSource> State<S> {
     where
         S::Frame: Default,
     {
+        self.stats.record_capture();
+
         let (mut surface, _drm_map, frame, buffer) =
             match mem::replace(&mut self.in_flight_surface, InFlightSurface::None) {
                 InFlightSurface::CopyQueued {
@@ -614,10 +625,29 @@ impl<S: CaptureSource> State<S> {
                 .is_some()
         };
         if should_encode {
+            let encode_start = Instant::now();
             if let Err(e) = enc.encode_frame(&surface) {
                 tracing::error!("encode_frame failed: {}", e);
                 self.errored = true;
             }
+            let encode_elapsed = encode_start.elapsed().as_micros() as u64;
+            self.stats.record_encode(&FrameTimings {
+                total_us: encode_elapsed,
+                ..Default::default()
+            });
+        }
+        self.stats_frames += 1;
+        if let Some(last) = self.stats_last_time {
+            if last.elapsed() >= std::time::Duration::from_secs(10) {
+                let delta = self.stats_frames;
+                let fps = delta as f64 / last.elapsed().as_secs_f64();
+                tracing::info!(frames = self.stats_frames, fps = format!("{fps:.1}"), "encoding stats");
+                self.stats_last_time = Some(std::time::Instant::now());
+                self.stats_frames = 0;
+            }
+        } else {
+            self.stats_start_time = Some(std::time::Instant::now());
+            self.stats_last_time = Some(std::time::Instant::now());
         }
     }
 
@@ -670,13 +700,23 @@ impl<S: CaptureSource> State<S> {
                 if let Err(e) = wrtc.write_h264_frame(&data, self.webrtc_frames_sent, self.args.fps) {
                     tracing::debug!("WebRTC write frame error: {e}");
                 }
+                self.stats.record_send(0.0, None);
                 self.webrtc_frames_sent = self.webrtc_frames_sent.saturating_add(1);
             }
             if count > 0 {
-                tracing::info!("WebRTC forwarded {count} frames from channel");
+                tracing::debug!("WebRTC forwarded {count} frames from channel");
             }
         }
 
+        if self.args.stats && self.stats.should_snapshot() {
+            self.stats.set_queue_depths(
+                0,
+                self.webrtc_rx.as_ref().map(|r| r.len()).unwrap_or(0),
+            );
+            let snap = self.stats.snapshot_and_reset();
+            tracing::info!("stats: {snap}");
+        }
+
         Ok(())
     }
 
@@ -995,8 +1035,7 @@ impl<S: CaptureSource> Dispatch<WlRegistry, GlobalListContents> for State<S> {
         qhandle: &QueueHandle<State<S>>,
     ) {
         use wayland_client::protocol::wl_registry::Event as RegistryEvent;
-        tracing::debug!("Dispatch<WlRegistry>::event fired: {:?}", event);
-
+        
         match event {
             RegistryEvent::Global {
                 name,

src/webrtc.rs

@@ -19,11 +19,13 @@ const HTML_PAGE: &str = r#"<!DOCTYPE html>
 video{max-width:90vw;max-height:80vh;border:1px solid #333}
 #status{margin:12px;font-size:14px;color:#aaa}
 #debug{position:fixed;bottom:8px;left:8px;font-size:11px;color:#666;max-width:90vw;white-space:pre-wrap}
+#stats-panel{position:fixed;top:8px;right:8px;background:rgba(0,0,0,0.7);color:#0f0;font:11px monospace;padding:6px 10px;border-radius:4px;z-index:100;pointer-events:none;max-width:90vw;white-space:pre;line-height:1.5}
 </style></head>
 <body>
 <div id="status">Connecting...</div>
 <video id="video" autoplay playsinline muted></video>
 <pre id="debug"></pre>
+<div id="stats-panel"></div>
 <script>
 const status = document.getElementById('status');
 const video  = document.getElementById('video');
@@ -51,25 +53,92 @@ function preferH264(sdp) {
 }
 
 function installStatsLogger(peer) {
+  const panel = document.getElementById('stats-panel');
+  let prev = null;
+  const intervalSecs = 1;
+
   setInterval(() => {
     if (peer !== pc) return;
-    const v = video;
-    log(`video: readyState=${v.readyState} currentTime=${v.currentTime.toFixed(2)} ` +
-        `paused=${v.paused} width=${v.videoWidth} height=${v.videoHeight} ` +
-        `srcObject=${v.srcObject ? 'yes' : 'no'}`);
     peer.getStats().then(stats => {
+      let rtp = null, rtt = null, codecStr = '';
+      let freezeCount = null, totalFreezesDuration = null;
+
       stats.forEach(report => {
-        if (report.type === 'inbound-rtp' && report.kind === 'video') {
-          log(`RTP-in: packetsReceived=${report.packetsReceived} packetsLost=${report.packetsLost} ` +
-              `bytesReceived=${report.bytesReceived} framesDecoded=${report.framesDecoded} ` +
-              `framesDropped=${report.framesDropped} codecId=${report.codecId}`);
-        }
-        if (report.type === 'codec' && report.mimeType && report.mimeType.includes('H264')) {
-          log(`Codec: ${report.mimeType} ${report.payloadType} sdpFmtpLine=${report.sdpFmtpLine}`);
+        if (report.type === 'inbound-rtp' && report.kind === 'video') rtp = report;
+        if (report.type === 'codec' && report.mimeType && report.mimeType.includes('H264'))
+          codecStr = report.mimeType + ' ' + (report.payloadType || '');
+        // candidate-pair: feature-detect 'selected' property
+        if (report.type === 'candidate-pair') {
+          const isSel = ('selected' in report) ? report.selected : report.state === 'succeeded';
+          if (isSel && typeof report.currentRoundTripTime === 'number') rtt = report.currentRoundTripTime;
         }
       });
+
+      // Freeze stats (feature-detect)
+      if (rtp && typeof rtp.freezeCount !== 'undefined') {
+        freezeCount = rtp.freezeCount;
+        totalFreezesDuration = rtp.totalFreezesDuration;
+      }
+
+      if (!rtp) return;
+
+      const cur = {
+        framesDecoded: rtp.framesDecoded || 0,
+        framesDropped: rtp.framesDropped || 0,
+        framesPerSecond: rtp.framesPerSecond || 0,
+        packetsLost: rtp.packetsLost || 0,
+        jitter: rtp.jitter || 0,
+        bytesReceived: rtp.bytesReceived || 0,
+        totalDecodeTime: rtp.totalDecodeTime || 0,
+        jitterBufferDelay: rtp.jitterBufferDelay || 0,
+        jitterBufferEmittedCount: rtp.jitterBufferEmittedCount || 0,
+        freezeCount: freezeCount,
+        totalFreezesDuration: totalFreezesDuration,
+        rtt: rtt,
+      };
+
+      // Raw log to debug element (backward compat)
+      log('RTP-in: decoded=' + cur.framesDecoded + ' lost=' + cur.packetsLost +
+          ' bytes=' + cur.bytesReceived + ' fps=' + cur.framesPerSecond +
+          (codecStr ? ' codec=' + codecStr : ''));
+
+      if (!prev) { prev = cur; return; }
+
+      // Compute deltas
+      const dFrames = cur.framesDecoded - prev.framesDecoded;
+      const dDropped = cur.framesDropped - prev.framesDropped;
+      const dLost = cur.packetsLost - prev.packetsLost;
+      const dBytes = cur.bytesReceived - prev.bytesReceived;
+      const dDecodeTime = cur.totalDecodeTime - prev.totalDecodeTime;
+      const dJitterBufDelay = cur.jitterBufferDelay - prev.jitterBufferDelay;
+      const dJitterBufCount = cur.jitterBufferEmittedCount - prev.jitterBufferEmittedCount;
+      const kbps = Math.round(dBytes * 8 / intervalSecs / 1000);
+      const decodeMs = dFrames > 0 ? (dDecodeTime / dFrames * 1000).toFixed(1) : '—';
+      const jitterBufMs = dJitterBufCount > 0 ? (dJitterBufDelay / dJitterBufCount * 1000).toFixed(1) : '—';
+      const jitterMs = (cur.jitter * 1000).toFixed(1);
+      const rttMs = cur.rtt !== null ? (cur.rtt * 1000).toFixed(1) : null;
+
+      let line = 'FPS:' + cur.framesPerSecond +
+        ' Decoded:' + cur.framesDecoded + '(+' + dFrames + ')' +
+        ' Dropped:' + cur.framesDropped + (dDropped > 0 ? '(+' + dDropped + ')' : '') +
+        ' Lost:' + dLost +
+        ' Jitter:' + jitterMs + 'ms' +
+        (rttMs !== null ? ' RTT:' + rttMs + 'ms' : '') +
+        ' Decode:' + decodeMs + 'ms' +
+        ' JBuf:' + jitterBufMs + 'ms';
+
+      if (freezeCount !== null) {
+        const dFreeze = cur.freezeCount - (prev.freezeCount || 0);
+        if (cur.freezeCount > 0 || dFreeze > 0)
+          line += ' Freeze:' + cur.freezeCount + '(+' + dFreeze + ')';
+      }
+
+      line += ' ' + kbps + 'kbps';
+
+      panel.textContent = line;
+      prev = cur;
     }).catch(() => {});
-  }, 2000);
+  }, intervalSecs * 1000);
 }
 
 function connect() {
@@ -178,12 +247,16 @@ impl WebRtcState {
                     HTML_PAGE.len(),
                     HTML_PAGE
                 );
-                let _ = stream.write_all(resp.as_bytes());
+                if let Err(e) = stream.write_all(resp.as_bytes()) {
+                    tracing::debug!("HTTP write error: {e}");
+                }
             } else if req_str.starts_with("POST /sdp") {
                 let body = extract_body(&req_str);
                 if body.is_empty() {
                     let resp = "HTTP/1.1 400 Bad Request\r\nConnection: close\r\n\r\nempty body";
-                    let _ = stream.write_all(resp.as_bytes());
+                    if let Err(e) = stream.write_all(resp.as_bytes()) {
+                        tracing::debug!("HTTP write error: {e}");
+                    }
                     continue;
                 }
 
@@ -206,17 +279,23 @@ impl WebRtcState {
                             answer_json.len(),
                             answer_json
                         );
-                        let _ = stream.write_all(resp.as_bytes());
+                        if let Err(e) = stream.write_all(resp.as_bytes()) {
+                            tracing::debug!("HTTP write error: {e}");
+                        }
                     }
                     Err(e) => {
                         tracing::error!("SDP offer handling failed: {e}");
                         let resp = "HTTP/1.1 500 Internal Server Error\r\nConnection: close\r\n\r\n";
-                        let _ = stream.write_all(resp.as_bytes());
+                        if let Err(e) = stream.write_all(resp.as_bytes()) {
+                            tracing::debug!("HTTP write error: {e}");
+                        }
                     }
                 }
             } else {
                 let resp = "HTTP/1.1 404 Not Found\r\nConnection: close\r\n\r\n";
-                let _ = stream.write_all(resp.as_bytes());
+                if let Err(e) = stream.write_all(resp.as_bytes()) {
+                    tracing::debug!("HTTP write error: {e}");
+                }
             }
         }
         Ok(handled)
@@ -225,7 +304,7 @@ impl WebRtcState {
     pub fn poll_rtc(&mut self) -> Result<()> {
         if let Some(inner) = self.inner.as_mut() {
             if inner.poll_rtc()? {
-                tracing::warn!("WebRTC connection closed/failed; clearing connection state");
+                tracing::info!("WebRTC connection closed; clearing connection state");
                 self.inner = None;
             }
         }
@@ -252,7 +331,7 @@ impl WebRtcState {
             false
         };
         if should_destroy {
-            tracing::warn!("WebRTC connection failed during write; clearing connection state");
+            tracing::info!("WebRTC connection failed during write; clearing connection state");
             self.inner = None;
         }
         Ok(())
@@ -270,10 +349,49 @@ impl WebRtcInner {
 
         let socket = UdpSocket::bind("0.0.0.0:0")?;
         socket.set_nonblocking(true)?;
+
+        // Increase UDP send buffer to absorb IDR frame bursts (256KB IDR → ~145 RTP
+        // packets in a single poll_rtc loop).  Default Linux wmem is ~208KB which
+        // causes EAGAIN on large keyframes.  2MB comfortably buffers several IDRs.
+        const SND_BUF_REQ: usize = 2 * 1024 * 1024;
+        // SAFETY: fd is a valid UDP socket; setsockopt/getsockopt with SOL_SOCKET +
+        // SO_SNDBUF are safe on Linux.  We check the return value and log the actual
+        // kernel-assigned buffer (Linux may cap at wmem_max and/or double the value).
+        unsafe {
+            let fd = std::os::unix::io::AsRawFd::as_raw_fd(&socket);
+            let val: libc::c_int = SND_BUF_REQ as libc::c_int;
+            let ret = libc::setsockopt(
+                fd,
+                libc::SOL_SOCKET,
+                libc::SO_SNDBUF,
+                &val as *const libc::c_int as *const libc::c_void,
+                std::mem::size_of::<libc::c_int>() as libc::socklen_t,
+            );
+            if ret < 0 {
+                tracing::warn!("setsockopt SO_SNDBUF failed (errno {})", std::io::Error::last_os_error());
+            }
+            let mut actual: libc::c_int = 0;
+            let mut actual_len: libc::socklen_t = std::mem::size_of::<libc::c_int>() as libc::socklen_t;
+            let gret = libc::getsockopt(
+                fd,
+                libc::SOL_SOCKET,
+                libc::SO_SNDBUF,
+                &mut actual as *mut libc::c_int as *mut libc::c_void,
+                &mut actual_len,
+            );
+            if gret == 0 {
+                tracing::info!(
+                    "UDP send buffer: requested {}KB, actual {}KB",
+                    SND_BUF_REQ / 1024,
+                    actual / 1024,
+                );
+            }
+        }
+
         let local_addr = socket.local_addr()?;
 
         let lan_ip = local_ip().unwrap_or_else(|| {
-            tracing::warn!("Failed to detect LAN IP, falling back to 127.0.0.1");
+            tracing::debug!("Failed to detect LAN IP, falling back to 127.0.0.1");
             "127.0.0.1".to_string()
         });
         let candidate_addr: SocketAddr = format!("{lan_ip}:{}", local_addr.port()).parse()?;
@@ -320,7 +438,7 @@ impl WebRtcInner {
         let mid = match self.video_mid {
             Some(m) => m,
             None => {
-                tracing::warn!("discover_video_params: no video_mid yet");
+                tracing::debug!("discover_video_params: no video_mid yet");
                 return;
             }
         };
@@ -344,13 +462,20 @@ impl WebRtcInner {
         loop {
             match self.rtc.poll_output() {
                 Ok(Output::Transmit(t)) => {
-                    tracing::info!("TX {} bytes -> {}", t.contents.len(), t.destination);
+                    tracing::trace!("TX {} bytes -> {}", t.contents.len(), t.destination);
                     if let Err(e) = self.socket.send_to(&t.contents, t.destination) {
-                        tracing::warn!("UDP send error: {e}");
+                        if e.kind() == std::io::ErrorKind::WouldBlock {
+                            tracing::debug!(
+                                "UDP send WouldBlock ({} bytes) — send buffer full",
+                                t.contents.len(),
+                            );
+                        } else {
+                            tracing::warn!("UDP send error to {}: {e}", t.destination);
+                        }
                     }
                 }
                 Ok(Output::Event(e)) => {
-                    tracing::info!("RTC event: {e:?}");
+                    tracing::debug!("RTC event: {e:?}");
                     match &e {
                         Event::Connected => {
                             tracing::info!("WebRTC connected!");
@@ -400,7 +525,7 @@ impl WebRtcInner {
                 Ok((n, source)) => {
                     recv_count += 1;
                     if recv_count <= 5 {
-                        tracing::info!("UDP recv {} bytes from {}", n, source);
+                        tracing::trace!("UDP recv {} bytes from {}", n, source);
                     }
                     let input = Input::Receive(
                         Instant::now(),
@@ -438,14 +563,14 @@ impl WebRtcInner {
         let mid = match self.video_mid {
             Some(m) => m,
             None => {
-                tracing::warn!("write_h264: no video_mid");
+                tracing::debug!("write_h264: no video_mid");
                 return Ok(false);
             }
         };
         let pt = match self.video_pt {
             Some(p) => p,
             None => {
-                tracing::warn!("write_h264: no video_pt");
+                tracing::debug!("write_h264: no video_pt");
                 return Ok(false);
             }
         };
@@ -474,7 +599,7 @@ impl WebRtcInner {
         let writer = match self.rtc.writer(mid) {
             Some(w) => w,
             None => {
-                tracing::warn!("write_h264: no writer for mid={mid}");
+                tracing::debug!("write_h264: no writer for mid={mid}");
                 return Ok(false);
             }
         };