server: stabilize uvc device selection

server/src/main.rs

@@ -5,6 +5,7 @@
 use anyhow::Context as _;
 use futures_util::{Stream, StreamExt};
 use gstreamer as gst;
+use std::path::Path;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 use std::{backtrace::Backtrace, panic, pin::Pin, sync::Arc};
@@ -141,7 +142,16 @@ fn pick_uvc_device() -> anyhow::Result<String> {
         return Ok(path);
     }
 
+    let ctrl = UsbGadget::find_controller().ok();
+    if let Some(ctrl) = ctrl.as_deref() {
+        let by_path = format!("/dev/v4l/by-path/platform-{ctrl}-video-index0");
+        if Path::new(&by_path).exists() {
+            return Ok(by_path);
+        }
+    }
+
     // walk /dev/video* via udev and look for an output‑capable node (gadget exposes one)
+    let mut fallback: Option<String> = None;
     if let Ok(mut en) = udev::Enumerator::new() {
         let _ = en.match_subsystem("video4linux");
         if let Ok(devs) = en.scan_devices() {
@@ -150,14 +160,33 @@ fn pick_uvc_device() -> anyhow::Result<String> {
                     .property_value("ID_V4L_CAPABILITIES")
                     .and_then(|v| v.to_str())
                     .unwrap_or_default();
-                if caps.contains(":video_output:") {
-                    if let Some(node) = dev.devnode() {
-                        return Ok(node.to_string_lossy().into_owned());
+                if !caps.contains(":video_output:") {
+                    continue;
+                }
+                let Some(node) = dev.devnode() else { continue };
+                let node = node.to_string_lossy().into_owned();
+                let product = dev
+                    .property_value("ID_V4L_PRODUCT")
+                    .and_then(|v| v.to_str())
+                    .unwrap_or_default();
+                let path = dev
+                    .property_value("ID_PATH")
+                    .and_then(|v| v.to_str())
+                    .unwrap_or_default();
+                if let Some(ctrl) = ctrl.as_deref() {
+                    if product == ctrl || path.contains(ctrl) {
+                        return Ok(node);
                     }
                 }
+                if fallback.is_none() {
+                    fallback = Some(node);
+                }
             }
         }
     }
+    if let Some(node) = fallback {
+        return Ok(node);
+    }
 
     Err(anyhow::anyhow!(
         "no video_output v4l2 node found; set LESAVKA_UVC_DEV"

server/src/video.rs

@@ -10,6 +10,8 @@ use gstreamer_app as gst_app;
 use lesavka_common::lesavka::VideoPacket;
 use tokio_stream::wrappers::ReceiverStream;
 use tonic::Status;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::Arc;
 use tracing::{Level, debug, enabled, error, info, trace, warn};
 
 const EYE_ID: [&str; 2] = ["l", "r"];
@@ -81,6 +83,14 @@ pub async fn eye_ball(dev: &str, id: u32, _max_bitrate_kbit: u32) -> anyhow::Res
     let eye = EYE_ID[id as usize];
     gst::init().context("gst init")?;
 
+    let target_fps = env_u32("LESAVKA_EYE_FPS", 25);
+    let frame_interval_us = if target_fps == 0 {
+        0
+    } else {
+        (1_000_000 / target_fps) as u64
+    };
+    let last_sent = Arc::new(AtomicU64::new(0));
+
     let desc = format!(
         "v4l2src name=cam_{eye} device=\"{dev}\" io-mode=mmap do-timestamp=true ! \
          queue ! \
@@ -166,6 +176,7 @@ pub async fn eye_ball(dev: &str, id: u32, _max_bitrate_kbit: u32) -> anyhow::Res
         }
     });
 
+    let last_sent_cloned = last_sent.clone();
     sink.set_callbacks(
         gst_app::AppSinkCallbacks::builder()
             .new_sample(move |sink| {
@@ -211,6 +222,14 @@ pub async fn eye_ball(dev: &str, id: u32, _max_bitrate_kbit: u32) -> anyhow::Res
                     .nseconds()
                     / 1_000;
 
+                if frame_interval_us > 0 {
+                    let last = last_sent_cloned.load(Ordering::Relaxed);
+                    if last != 0 && pts_us.saturating_sub(last) < frame_interval_us {
+                        return Ok(gst::FlowSuccess::Ok);
+                    }
+                    last_sent_cloned.store(pts_us, Ordering::Relaxed);
+                }
+
                 /* -------- ship over gRPC ----- */
                 let data = map.as_slice().to_vec();
                 let size = data.len();