feat: add example for uvc streamer

examples/vision/streaming/uvc_stream.py

@@ -0,0 +1,26 @@
+from maix import camera, display, app, time, uvc
+
+cam = camera.Camera(640, 360)   # Manually set resolution
+                                # | 手动设置分辨率
+# disp = display.Display()        # MaixCAM default is 522x368
+                                # | MaixCAM 默认是 522x368
+
+uvcs = uvc.UvcStreamer(0)
+# uvcs.use_mjpg(1) for mjpg or yuyv default without it
+# uvcs.use_mjpg(1) 是为了刷 mjpg 通道，不添加这一行默认是 yuyv 通道
+uvcs.use_mjpg(1)
+
+while not app.need_exit():
+    # time.fps_start()          # Manually set fps calculation start point, comment here mean last time fps() call is start
+                                # | 动设置帧率（FPS）计算开始点，这里注释了表示上一次 fps 函数即是开始
+    img = cam.read()            # Get one frame from camera, img is maix.image.Image type object
+                                # | 从摄像头获取一帧图像，img 是 maix.image.Image 类型的对象
+    # disp.show(img)              # Show image to screen
+                                # | 将图像显示到屏幕
+    uvcs.show(img)
+
+    fps = time.fps()            # Calculate FPS between last time fps() call and this time call.
+                                # | 计算两次 fps 函数调用之间的帧率
+    print(f"time: {1000/fps:.02f}ms, fps: {fps:.02f}") # print FPS in console
+                                                       # | 在终端打印帧率（FPS）
+

tools/os/gen_os.sh

@@ -148,7 +148,7 @@ cp -r "tmp/sys_builtin_files/boot/boards" "tmp/sys_builtin_files/maixapp/"
 ./update_img.sh tmp/sys_builtin_files "tmp/$os_version_str.img"
 
 # 9. xz 压缩镜像
-xz -zv "tmp/$os_version_str.img"
+xz -zv -T 0 "tmp/$os_version_str.img"
 
 echo "Complete: os file: tmp/$os_version_str.img.xz"
 

tools/os/update_img.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 
 set -e
+set -o pipefail
 
 source_dir=$1
 img_file=$2
@@ -34,7 +35,9 @@ $THISDIR/fuse2fs -o fakeroot -o offset=$PART_OFFSET $img_file $mount_root
 
 # copy root files
 echo "copy root files now"
-find $source_dir -mindepth 1 -maxdepth 1 -type d ! -name "boot" -exec cp -r {} $mount_root \;
+find $source_dir -mindepth 1 -maxdepth 1 -type d ! -name "boot" | while read -r dir; do
+    cp -r "$dir" "$mount_root"
+done
 sync
 echo "copy root files done"