fix： 树莓派gstreamer pipeline报错

examples/camera_demo.rs

@@ -128,9 +128,23 @@ fn create_demo_config() -> Config {
         
     // 根据操作系统和设备类型自动选择合适的设备路径
     let device = if is_raspberry_pi {
-        // 使用更简单的GStreamer pipeline，尝试不同配置方式和格式
-        // 此pipeline尝试放宽限制，避免严格的格式约束
-        "v4l2src ! videoconvert ! appsink".to_string()
+        // 尝试读取可用设备列表
+        match std::process::Command::new("v4l2-ctl").arg("--list-devices").output() {
+            Ok(output) => {
+                let devices = String::from_utf8_lossy(&output.stdout);
+                info!("检测到视频设备:\n{}", devices);
+                
+                // 根据输出查找最可能是摄像头的设备
+                if devices.contains("/dev/video0") {
+                    // 使用USB摄像头，优先选择video1而不是video0，可能会更稳定
+                    "v4l2src device=/dev/video0 ! videoconvert ! appsink".to_string()
+                } else {
+                    // 回退到默认配置
+                    "v4l2src ! videoconvert ! appsink".to_string()
+                }
+            },
+            Err(_) => "v4l2src ! videoconvert ! appsink".to_string()
+        }
     } else if std::env::consts::OS == "linux" {
         "/dev/video0".to_string()
     } else if std::env::consts::OS == "macos" {

src/camera/controller.rs

@@ -95,12 +95,20 @@ impl CameraController {
                 .context("Failed to lock focus at infinity")?;
         }
 
+        // 给相机一点时间初始化
+        info!("Waiting for camera to stabilize...");
+        tokio::time::sleep(tokio::time::Duration::from_millis(500)).await;
+        
         // 尝试拍摄测试帧以确保相机设置正确
         info!("Testing camera by capturing a test frame...");
-        let mut test_stream = match camera.start_streaming() {
-            Ok(stream) => stream,
+        
+        // 使用已打开的相机实例直接捕获一帧，而不是创建新的流
+        match camera.capture_test_frame() {
+            Ok(_) => {
+                info!("Successfully captured test frame - camera is working correctly");
+            },
             Err(e) => {
-                error!("Failed to start test stream: {}", e);
+                error!("Failed to capture test frame: {}", e);
                 
                 // 检查是否在树莓派上，以及是否已经使用GStreamer
                 let is_raspberry_pi = std::fs::read_to_string("/proc/cpuinfo")
@@ -124,17 +132,6 @@ impl CameraController {
                 
                 return Err(anyhow::anyhow!("Camera initialization failed: {}", e));
             }
-        };
-        
-        // 尝试捕获测试帧
-        match test_stream.capture_frame() {
-            Ok(_) => {
-                info!("Successfully captured test frame - camera is working correctly");
-            },
-            Err(e) => {
-                error!("Failed to capture test frame: {}", e);
-                return Err(anyhow::anyhow!("Camera initialization failed: Unable to capture test frame"));
-            }
         }
 
         self.camera = Some(camera);
@@ -165,7 +162,7 @@ impl CameraController {
         info!("Starting camera streaming with device: {}", self.settings.device);
         let stream_result = camera.start_streaming();
         
-        let stream = match stream_result {
+        let mut stream = match stream_result {
             Ok(stream) => stream,
             Err(e) => {
                 error!("Failed to start camera streaming: {}", e);
@@ -211,20 +208,25 @@ impl CameraController {
             }
         };
 
+        // 先保存一个测试帧副本
+        let test_frame = match stream.capture_frame() {
+            Ok(frame) => {
+                info!("Successfully captured test frame from stream - camera stream is working correctly");
+                Some(frame)
+            },
+            Err(e) => {
+                error!("Test frame capture failed: {}", e);
+                return Err(anyhow::anyhow!("Camera stream test failed: {}", e));
+            }
+        };
+        
+        // 现在可以安全地移动stream的所有权
         self.stream = Some(stream);
         self.is_running = true;
-
-        // 尝试捕获一个测试帧，确保流工作正常
-        if let Some(mut stream_test) = self.stream.as_mut() {
-            match stream_test.capture_frame() {
-                Ok(_) => info!("Successfully captured test frame - camera stream is working correctly"),
-                Err(e) => {
-                    error!("Test frame capture failed: {}", e);
-                    self.is_running = false;
-                    self.stream = None;
-                    return Err(anyhow::anyhow!("Camera stream test failed: {}", e));
-                }
-            }
+        
+        // 如果有测试帧，则处理它（如果需要）
+        if test_frame.is_some() {
+            debug!("Test frame was successfully captured");
         }
 
         // Clone necessary values for the capture task

src/camera/opencv.rs

@@ -435,6 +435,28 @@ impl OpenCVCamera {
         Ok(())
     }
     
+    /// 捕获一个测试帧（不创建单独的流）
+    pub fn capture_test_frame(&mut self) -> Result<core::Mat> {
+        info!("Capturing test frame from main camera instance");
+        
+        if !self.capture.is_opened()? {
+            return Err(anyhow!("Camera is not open"));
+        }
+        
+        let mut frame = core::Mat::default();
+        
+        // 尝试捕获帧
+        if self.capture.read(&mut frame)? {
+            if frame.empty() {
+                return Err(anyhow!("Captured frame is empty"));
+            }
+            info!("Successfully captured test frame, size: {}x{}", frame.cols(), frame.rows());
+            Ok(frame)
+        } else {
+            Err(anyhow!("Failed to capture test frame"))
+        }
+    }
+    
     /// Check if the camera is currently streaming
     pub fn is_streaming(&self) -> bool {
         self.is_streaming