---
## 基本知識
---
* USB 運作模式
* 『Host 負責主導整個 USB 結構的通訊』，會輪詢所有裝置需要傳送資料
* 將以 PCI Bus 的形式存在供作業系統控制
* lspci
```
root@opkiller:~# lspci
00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 / PCIe bridge (rev 01)
```
* USB 架構規範
* 模式(Configurations)：只能一種模式，不能同時兩種模式並行運作。(韌體升級/一般模式)。
* 介面(Interfaces)：一個 USB 裝置可能有很多個輸入或輸出介面。
* 設定值(Settings)
* 端點(Endpoints)
* USB Device 初始化流程
* Host -> (GET/**問**) Device Descriptors = Enumeration
* Device Descriptors
* GET -> 模式的數量(bNumConfigurations) => Configuration Descriptors
* GET -> 介面的數量(bNumInterfaces) => Interface
* GET -> 端點的數量(bNumEndpoints) => **Endpoint (傳輸資料)**
* **Endpoint 的傳輸形態**：
* Control 控制中斷模式 : 須有足夠頻寬完成每次傳輸(使用 Endpoint 0)。
* Bulk 批量傳輸 : 大量且安全的傳輸，且能夠分批。
* Isochronous 同步傳輸 : 大量且穩定持續但不保證安全的傳輸。
* Interrupt 中斷傳輸: 以輪詢機制來請求傳輸
* GET -> 端點的資料傳輸模式(bmAttributes)
* list-devices 定義
* USB PHY 2.0 : 指 USB 2.0 的物理層（Physical Layer）
* USB 2.0 Camera : 指一個使用 USB 2.0 介面的攝像頭
* 最大頻寬 (share in every device)
* USB 2.0 最大頻寬為 480 Mbps（兆位元每秒）
* USB 3.0 Gen 1 最大頻寬為 5 Gbps（兆位元每秒）- 超速（SuperSpeed）模式
* USB 3.0 Gen 2 最大頻寬為 10 Gbps（兆位元每秒）
* 每個 USB 裝置的頻寬計算([粗略](https://www.mistralsolutions.com/articles/video-surveillance-bandwidth-requirements-calculation-utilization/))
* Frame Size = Resolution * Colour Depth
* Bit Rate = Frame Size * Frame Rate (fps)
* Example
* Frame Size = (1280x720)x(8x3) = 22,118,400 bits = ~ 22.11 Mbps (Mbits/sec)
* Bit Rate (Minimum Bandwidth) = 22.1184 Mbps * 30 = ~ 663 Mbps (Mbits/sec)
Note : Maximum Bandwidth of USB 2.0 is 480 Mbps
* 每個 USB 裝置的頻寬計算(實際)
* 取決於多個因素，包括裝置本身的能力、連接的USB控制器和主機系統的支援能力。
* 例子，如何計算 UVC Camera 的 Mbps 傳輸速率是否足夠
1. 取得各 UVC 每禎所需要的頻寬
* dmesg : Selecting alternate setting 11 (3060 B/frame bandwidth).
* 每幀的長度為 125us
* 每幀 3060 位元組等於 195 Mbps (3060 x 1000000/125 x 8)
2. 計算當前所使用的 UVC 格式所傳輸的頻寬
UVC Camera 所使用 RGB, 240p @ 25 FPS => 320x240x3x25 = 5760000 byte = 46 MB
* 嵾考文獻
1. [Multiple UVC cameras on Linux: an unexpected challenge](https://www.thegoodpenguin.co.uk/blog/multiple-uvc-cameras-on-linux/)
2. [Understanding why USB Isochronous Bandwidth Errors Occur](https://www.thegoodpenguin.co.uk/blog/understanding-why-usb-isochronous-bandwidth-errors-occur/)
3. [淺談 USB 通訊架構之定義（一）](https://fred-zone.blogspot.com/2009/08/usb.html)
4. [淺談 USB 通訊架構之定義（二）](https://fred-zone.blogspot.com/2009/08/usb_10.html)
</br>
---
## 實驗 1 : i.MX8 能否同時運行雙顆 UVC 攝像頭
<p style="font-size: larger;">主要原因是 USB 2.0 的共享頻寬限制</p>
---
### Research Result
* Research USB Interface by using **dual- UCV camera** with difference resolution
* 預計 MJPG 的壓縮比為 10:1
| Resolution | Bandwidth (bps) |i.MX8MP|i.MX8MM|
|---|---|---|---|
| **Hub 2.0 + dual camera USB 2.0:**|||
|2 x 240p@30fps (MJPEG,YUV)| 5.5M + 36M |**Work**|Fail|
|2 x 480p@30fps (MJPEG,YUV)| 22M+ **147M** |Fail|Fail|
|480p@30fps, 240p@30fps (MJPEG YUV)| 22M + 36M |Fail|Fail|
|480p@25fps, 240p@30fps(YUV,YUV)| 184M + 36M |Fail|Fail|
|720p@5fps, 240p@30fps(YUV,YUV) |73M + 36M |**Work**|Fail|
| **Hub 3.0 + dual camera USB 2.0:**|||
|2 x 240p@30fps (MJPEG,YUV)| 5.5M + 36M |**Work**|Fail|
|2 x 480p@30fps (MJPEG,YUV)| 22M + 147M |Fail|Fail|
|480p@30fps, 240p@30(MJPEG YUV)| 22M + 36M |**Work**|Fail|
|720p@30fps, 240p@30(MJPEG YUV)| 66M + 36M |**Work**|Fail|
|1080p@30fps, 240p@30(MJPEG YUV)| 149M + 36M |**Work**|Fail|
|480p@25fps, 240p@30fps(YUV,YUV)| 184M + 36M |**Work**|Fail|
|720p@5fps, 240p@30fps(YUV,YUV) |73M + 36M |**Work**|Fail|
</br>
* 造成雙鏡頭的 Fail 原因之一 : 頻寬不足
* Message : Failed to submit URB 0 (-28)
* Answer
* **Debug** : uvc_video.c , [linux-imx/version/git/drivers/media/usb/uvc]
* URB（USB Request Block） 是 USB 驅動程式和 USB 設備之間進行通信的基本單位
* Error : Failed to submit URB 0 (-28) => 傳輸接收封包錯誤 = **頻寬不足**
```c++
//(1) URB 添加到 UVC 驅動程式的 URB 隊列中，並觸發相應的 USB 傳輸操作
/* Submit the URBs. */
for_each_uvc_urb(uvc_urb, stream) {
ret = uvc_submit_urb(uvc_urb, gfp_flags);
if (ret < 0) {
dev_err(&stream->intf->dev,
"Failed to submit URB %u (%d).\n",
uvc_urb_index(uvc_urb), ret);
uvc_video_stop_transfer(stream, 1);
return ret;
}
}
//(2) 用於支援 USB 視訊設備的驅動程式，它負責處理視訊數據的捕獲、編碼、解碼和顯示等操作
static int uvc_submit_urb(struct uvc_urb *uvc_urb, gfp_t mem_flags)
{
/* Sync DMA. */
dma_sync_sgtable_for_device(uvc_stream_to_dmadev(uvc_urb->stream),
uvc_urb->sgt,
uvc_stream_dir(uvc_urb->stream));
return usb_submit_urb(uvc_urb->urb, mem_flags);
}
//(3) 支援各種不同的 USB 設備，包括存儲設備、音訊設備、輸入設備等
//link web = https://www.cnblogs.com/tureno/articles/6811367.html
```
* **Graph of USB 2.0 HUB**
Note : 因頻寬被均分給每個裝置(HUB + Camera * 2), 故每裝置的頻寬約 160 Mbps
* 參考網站
* [usb_submit_urb流程分析](https://www.twblogs.net/a/5e4edfb4bd9eee101df63c96)
* [linux设备驱动之USB数据传输分析 usb_submit_urb](https://www.cnblogs.com/tureno/articles/6811367.html)
* [vcvideo: Failed to submit URB 0 (-28)](https://support.xilinx.com/s/question/0D52E00006hpYmcSAE/uvcvideo-failed-to-submit-urb-0-28?language=en_US) -> replace USB 1.0 Hub to USB 2.0 Hub
* [intr_urb_submit failed:-28 / No space left on device](https://e2e.ti.com/support/processors-group/processors/f/processors-forum/136197/intr_urb_submit-failed--28-no-space-left-on-device)
* [**Linux 下打開多個 UVC 攝像頭報錯問題**](https://blog.csdn.net/qq_20862815/article/details/129163401)
* 問題 ioctl(fd, VIDIC_STREAMON, &type) => 頻寬分配問題 = 並**非均分概念**
* 解決方式 : 修改 vMaxPacketSize 與 bInterval
* vMaxPacketSize 表示每次傳輸所使用的封包大小, 最大值 3072 (0x1400) 字節
* bInterval 表示每次間隔多久時間傳輸, 數值 1 為最快(125us) 至 數值 16 為最快(2^(15) * 125us)
* USB BitRate and Bandwidth (Hub + Dual UVC Camera)
```
root@op-kiler-kivy:~# lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
|__ Port 1: Dev 10, If 0, Class=Video, Driver=uvcvideo, 480M
|__ Port 1: Dev 10, If 1, Class=Video, Driver=uvcvideo, 480M
|__ Port 2: Dev 11, If 3, Class=Audio, Driver=snd-usb-audio, 480M
|__ Port 2: Dev 11, If 1, Class=Video, Driver=uvcvideo, 480M
|__ Port 2: Dev 11, If 2, Class=Audio, Driver=snd-usb-audio, 480M
|__ Port 2: Dev 11, If 0, Class=Video, Driver=uvcvideo, 480M
```
</br>
</br>
---
### Device Info
$ v4l2-ctl --list-devices
```
root@opkiller:~# v4l2-ctl --list-devices
():
/dev/v4l-subdev0
/dev/v4l-subdev2
/dev/v4l-subdev3
(csi0):
/dev/v4l-subdev1
FSL Capture Media Device (platform:32c00000.bus:camera):
/dev/media1
VIV (platform:viv0):
/dev/video4
vsi_v4l2dec (platform:vsi_v4l2dec):
/dev/video1
vsi_v4l2enc (platform:vsi_v4l2enc):
/dev/video0
viv_media (platform:vvcam-video.0):
/dev/media2
USB PHY 2.0: USB 2.0 Camera (usb-xhci-hcd.1.auto-1.1):
/dev/video2
/dev/video3
/dev/media0
USB2.0 Camera: USB2.0 Camera (usb-xhci-hcd.1.auto-1.4):
/dev/video5
/dev/video6
/dev/media3
```
$ v4l2-ctl -d /dev/video2 --list-formats-ext
```
root@op-kiler-kivy:~# v4l2-ctl -d /dev/video2 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
[0]: 'MJPG' (Motion-JPEG, compressed)
Size: Discrete 1920x1080
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 1280x720
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 352x288
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 320x240
Interval: Discrete 0.033s (30.000 fps)
[1]: 'YUYV' (YUYV 4:2:2)
Size: Discrete 1280x720
Interval: Discrete 0.200s (5.000 fps)
Size: Discrete 640x480
Interval: Discrete 0.040s (25.000 fps)
Size: Discrete 640x360
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 352x288
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 320x240
Interval: Discrete 0.033s (30.000 fps)
```
$ v4l2-ctl -d /dev/video5 --list-formats-ext
```
root@op-kiler-kivy:~# v4l2-ctl -d /dev/video5 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
[0]: 'YUYV' (YUYV 4:2:2)
Size: Discrete 640x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 160x120
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 176x144
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 320x240
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 352x288
Interval: Discrete 0.033s (30.000 fps)
```
</br>
</br>
---
### Platform : NXP i.MX8M Plus
#### (1) I.MX8M PLUS , dual USB-Webcamera , 640x480 (YUV + MJPG)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=640,height=480,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video2 ! \
jpegdec ! video/x-raw,width=640,height=480,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
</br>
#### (2) I.MX8M PLUS , dual USB-Webcamera , 320x240 (YUV + MJPG)
* It's **work**
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=320,height=240,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video2 ! \
jpegdec ! video/x-raw,width=320,height=240,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
</br>
#### (3) I.MX8M PLUS , dual USB-Webcamera , 480p@30 and 240p@30 (YUV + MJPG)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=640,height=480,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video2 ! \
jpegdec ! video/x-raw,width=320,height=240,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
#### (4) I.MX8M PLUS , dual USB-Webcamera , 480p@25 and 240p@30 (YUV + YUV)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video2 ! \
"video/x-raw,format=YUY2,width=640,height=480,framerate=25/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=320,height=240" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
#### (5) I.MX8M PLUS , dual USB-Webcamera , 720p@5fps and 240p@30fps (YUV + YUV)
* It's **work**
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video2 ! \
"video/x-raw,format=YUY2,width=1280,height=720,framerate=5/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=320,height=240" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
</br>
</br>
</br>
### Platform : NXP i.MX8M Min
#### (1) I.MX8M Min , dual USB-Webcamera , 640x480 (YUV + MJPG)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video3 ! \
"video/x-raw,format=YUY2,width=640,height=480,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video5 ! \
jpegdec ! video/x-raw,width=640,height=480,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
</br>
#### (2) I.MX8M Min , dual USB-Webcamera , 320x240 (YUV + MJPG)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video3 ! \
"video/x-raw,format=YUY2,width=320,height=240,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video5 ! \
jpegdec ! video/x-raw,width=320,height=240,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
</br>
#### (3) I.MX8M Min , dual USB-Webcamera , 480p and 240p (YUV + MJPG)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video3 ! \
"video/x-raw,format=YUY2,width=640,height=480,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video5 ! \
jpegdec ! video/x-raw,width=320,height=240,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
#### (4) I.MX8M Min , dual USB-Webcamera , 480p@25 and 240p@30 (YUV + YUV)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=640,height=480,framerate=25/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video3 ! \
"video/x-raw,format=YUY2,width=320,height=240" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
#### (5) I.MX8M Min dual USB-Webcamera , 720p@5fps and 240p@30fps (YUV + YUV)
* It's fail (Failed to allocate required memory.)
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video5 ! \
"video/x-raw,format=YUY2,width=1280,height=720,framerate=5/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video3 ! \
"video/x-raw,format=YUY2,width=320,height=240" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
</br>
</br>
</br>
---
## 實驗 2 : MJPG 與 YUV 是否會造成 CPU 使用率上升
<p style="font-size: larger;">MJPG (use 47% CPU) , YUV (use 15% CPU) </p>
---
### 使用 MJPG 的 CPU 使用率
* 代碼
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video6 ! \
"video/x-raw,format=YUY2,width=320,height=240,framerate=30/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video4 ! \
jpegdec ! video/x-raw,width=1280,height=720,framerate=30/1 ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
* 結果
</br>
### 使用 YUV 的 CPU 使用率
* 代碼
```
gst-launch-1.0 \
imxcompositor_g2d \
background=0x000000FF \
name=comp \
sink_0::xpos=0 sink_0::ypos=0 \
sink_0::width=640 sink_0::height=480 \
sink_1::xpos=640 sink_1::ypos=0\
sink_1::width=640 sink_1::height=480 ! \
waylandsink \
v4l2src device=/dev/video4 ! \
"video/x-raw,format=YUY2,width=1280,height=720,framerate=5/1" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_0 \
v4l2src device=/dev/video6 ! \
"video/x-raw,format=YUY2,width=320,height=240" ! \
imxvideoconvert_g2d ! video/x-raw, width=640, height=480! \
comp.sink_1
```
* 結果
</br>
</br>
</br>
---
## 實驗 3 : 了解 USB / UVC Camera Information
---
### Info
```
Bus 001 Device 007: ID 1124:2925 Jieli Technology USB PHY 2.0
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x1124
idProduct 0x2925
bcdDevice 1.00
iManufacturer 1 Jieli Technology
iProduct 2 USB PHY 2.0
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0345
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 6 USB 2.0 Camera
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 0
iInterface 6 USB 2.0 Camera
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 0x0067
dwClockFrequency 30.000000MHz
bInCollection 1
baInterfaceNr( 0) 1
VideoControl Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Camera Sensor
bAssocTerminal 0
iTerminal 0
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 3
bmControls 0x00000000
VideoControl Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 5 (PROCESSING_UNIT)
Warning: Descriptor too short
bUnitID 2
bSourceID 1
wMaxMultiplier 0
bControlSize 2
bmControls 0x00000040
White Balance Temperature
iProcessing 0
bmVideoStandards 0x1a
NTSC - 525/60
SECAM - 625/50
NTSC - 625/50
VideoControl Interface Descriptor:
bLength 26
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 3
guidExtensionCode {28f03370-6311-4a2e-ba2c-6890eb334016}
bNumControls 8
bNrInPins 1
baSourceID( 0) 2
bControlSize 1
bmControls( 0) 0x00
iExtension 0
VideoControl Interface Descriptor:
bLength 26
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 4
guidExtensionCode {dddf7394-973e-4727-bed9-04ed6426dc67}
bNumControls 8
bNrInPins 1
baSourceID( 0) 3
bControlSize 1
bmControls( 0) 0x00
iExtension 0
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 5
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 4
iTerminal 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x85 EP 5 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 4
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
VideoStreaming Interface Descriptor:
bLength 15
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormats 2
wTotalLength 0x01b3
bEndpointAddress 0x84 EP 4 IN
bmInfo 0
bTerminalLink 5
bStillCaptureMethod 2
bTriggerSupport 1
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 0
bmaControls( 1) 0
VideoStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 6 (FORMAT_MJPEG)
bFormatIndex 1
bNumFrameDescriptors 6
bFlags 0
Fixed-size samples: No
bDefaultFrameIndex 1
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 1 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 1920
wHeight 1080
dwMinBitRate 497664000
dwMaxBitRate 995328000
dwMaxVideoFrameBufferSize 4147200
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 1280
wHeight 720
dwMinBitRate 221184000
dwMaxBitRate 442368000
dwMaxVideoFrameBufferSize 1843200
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 73728000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 360
dwMinBitRate 55296000
dwMaxBitRate 110592000
dwMaxVideoFrameBufferSize 460800
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 24330240
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 6
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 18432000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 22
bDescriptorType 36
bDescriptorSubtype 3 (STILL_IMAGE_FRAME)
bEndpointAddress 0x00 EP 0 OUT
bNumImageSizePatterns 3
wWidth( 0) 1280
wHeight( 0) 720
wWidth( 1) 640
wHeight( 1) 480
wWidth( 2) 320
wHeight( 2) 240
bNumCompressionPatterns 4
bCompression( 0) 1
bCompression( 1) 5
bCompression( 2) 10
bCompression( 3) 20
VideoStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 13 (COLORFORMAT)
bColorPrimaries 1 (BT.709,sRGB)
bTransferCharacteristics 1 (BT.709)
bMatrixCoefficients 4 (SMPTE 170M (BT.601))
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED)
bFormatIndex 2
bNumFrameDescriptors 5
guidFormat {32595559-0000-0010-8000-00aa00389b71}
bBitsPerPixel 16
bDefaultFrameIndex 1
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 2 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 1280
wHeight 720
dwMinBitRate 221184000
dwMaxBitRate 442368000
dwMaxVideoFrameBufferSize 1843200
dwDefaultFrameInterval 2000000
bFrameIntervalType 1
dwFrameInterval( 0) 2000000
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 73728000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 400000
bFrameIntervalType 1
dwFrameInterval( 0) 400000
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 360
dwMinBitRate 55296000
dwMaxBitRate 110592000
dwMaxVideoFrameBufferSize 460800
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 24330240
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 18432000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 3 (STILL_IMAGE_FRAME)
bEndpointAddress 0x00 EP 0 OUT
bNumImageSizePatterns 3
wWidth( 0) 1280
wHeight( 0) 720
wWidth( 1) 640
wHeight( 1) 480
wWidth( 2) 320
wHeight( 2) 240
bNumCompressionPatterns 0
VideoStreaming Interface Descriptor:
bLength 6
bDescriptorType 36
bDescriptorSubtype 13 (COLORFORMAT)
bColorPrimaries 1 (BT.709,sRGB)
bTransferCharacteristics 1 (BT.709)
bMatrixCoefficients 4 (SMPTE 170M (BT.601))
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x1400 3x 1024 bytes
bInterval 1
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 2
bInterfaceCount 2
bFunctionClass 1 Audio
bFunctionSubClass 2 Streaming
bFunctionProtocol 0
iFunction 5 USB Microphone
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 0
iInterface 5 USB Microphone
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 1.00
wTotalLength 0x0026
bInCollection 1
baInterfaceNr(0) 3
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 0
bNrChannels 1
wChannelConfig 0x0003
Left Front (L)
Right Front (R)
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 8
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 3
bSourceID 1
bControlSize 1
bmaControls(0) 0x03
Mute Control
Volume Control
iFeature 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 2
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 3
iTerminal 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5 USB Microphone
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5 USB Microphone
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 0x0001 PCM
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 1 Discrete
tSamFreq[ 0] 8000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0060 1x 96 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioStreaming Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 2
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5 USB Microphone
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 0x0001 PCM
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 1 Discrete
tSamFreq[ 0] 16000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0060 1x 96 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioStreaming Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 3
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5 USB Microphone
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 0x0001 PCM
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 1 Discrete
tSamFreq[ 0] 44100
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0060 1x 96 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioStreaming Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 4
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 5 USB Microphone
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 0x0001 PCM
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 1 Discrete
tSamFreq[ 0] 48000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x0060 1x 96 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioStreaming Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
Device Status: 0x0001
Self Powered
root@opkiller:~# ^C
root@opkiller:~# lsusb -d 214b:7250 -v
Bus 001 Device 002: ID 214b:7250 Huasheng Electronics USB2.0 HUB
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 9 Hub
bDeviceSubClass 0
bDeviceProtocol 1 Single TT
bMaxPacketSize0 64
idVendor 0x214b Huasheng Electronics
idProduct 0x7250
bcdDevice 1.00
iManufacturer 0
iProduct 1 USB2.0 HUB
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 0x0019
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
Self Powered
Remote Wakeup
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 9 Hub
bInterfaceSubClass 0
bInterfaceProtocol 0 Full speed (or root) hub
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0001 1x 1 bytes
bInterval 12
Hub Descriptor:
bLength 9
bDescriptorType 41
nNbrPorts 4
wHubCharacteristic 0x00e0
Ganged power switching
Ganged overcurrent protection
TT think time 32 FS bits
Port indicators
bPwrOn2PwrGood 50 * 2 milli seconds
bHubContrCurrent 100 milli Ampere
DeviceRemovable 0x00
PortPwrCtrlMask 0xff
Hub Port Status:
Port 1: 0000.0100 power
Port 2: 0000.0100 power
Port 3: 0000.0507 highspeed power suspend enable connect
Port 4: 0000.0507 highspeed power suspend enable connect
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 9 Hub
bDeviceSubClass 0
bDeviceProtocol 0 Full speed (or root) hub
bMaxPacketSize0 64
bNumConfigurations 1
Device Status: 0x0001
Self Powered
```
### Bandwidth
* (1) lsusb
```
root@op-kiler-kivy:~/nnstreamer# lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
|__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
|__ Port 1: Dev 10, If 0, Class=Video, Driver=uvcvideo, 480M
|__ Port 1: Dev 10, If 1, Class=Video, Driver=uvcvideo, 480M
|__ Port 2: Dev 11, If 3, Class=Audio, Driver=snd-usb-audio, 480M
|__ Port 2: Dev 11, If 1, Class=Video, Driver=uvcvideo, 480M
|__ Port 2: Dev 11, If 2, Class=Audio, Driver=snd-usb-audio, 480M
|__ Port 2: Dev 11, If 0, Class=Video, Driver=uvcvideo, 480M
```
* (2) usb-devices
* single camera
```c++
root@op-kiler-kivy:~/nnstreamer# usb-devices
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 1
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=1d6b ProdID=0002 Rev=05.15
S: Manufacturer=Linux 5.15.52+g36363d8623ba xhci-hcd
S: Product=xHCI Host Controller
S: SerialNumber=xhci-hcd.1.auto
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 12 Spd=480 MxCh= 0
D: Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=1871 ProdID=01f0 Rev=00.08
S: Manufacturer=AVEO Technology Corp.
S: Product=USB2.0 Camera
C: #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=500mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=0e(video) Sub=01 Prot=00 Driver=uvcvideo
E: Ad=85(I) Atr=03(Int.) MxPS= 8 Ivl=8ms
I: If#= 1 Alt= 0 #EPs= 0 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=5000 MxCh= 1
D: Ver= 3.00 Cls=09(hub ) Sub=00 Prot=03 MxPS= 9 #Cfgs= 1
P: Vendor=1d6b ProdID=0003 Rev=05.15
S: Manufacturer=Linux 5.15.52+g36363d8623ba xhci-hcd
S: Product=xHCI Host Controller
S: SerialNumber=xhci-hcd.1.auto
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms
```
* dual camera
```c++
root@op-kiler-kivy:~/nnstreamer# usb-devices
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 1
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=1d6b ProdID=0002 Rev=05.15
S: Manufacturer=Linux 5.15.52+g36363d8623ba xhci-hcd
S: Product=xHCI Host Controller
S: SerialNumber=xhci-hcd.1.auto
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 13 Spd=480 MxCh= 4
D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=214b ProdID=7250 Rev=01.00
S: Product=USB2.0 HUB
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=256ms
T: Bus=01 Lev=02 Prnt=13 Port=02 Cnt=01 Dev#= 14 Spd=480 MxCh= 0
D: Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 1
P: Vendor=1871 ProdID=01f0 Rev=00.08
S: Manufacturer=AVEO Technology Corp.
S: Product=USB2.0 Camera
C: #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=500mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=0e(video) Sub=01 Prot=00 Driver=uvcvideo
E: Ad=85(I) Atr=03(Int.) MxPS= 8 Ivl=8ms
I: If#= 1 Alt= 0 #EPs= 0 Cls=0e(video) Sub=02 Prot=00 Driver=uvcvideo
T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=5000 MxCh= 1
D: Ver= 3.00 Cls=09(hub ) Sub=00 Prot=03 MxPS= 9 #Cfgs= 1
P: Vendor=1d6b ProdID=0003 Rev=05.15
S: Manufacturer=Linux 5.15.52+g36363d8623ba xhci-hcd
S: Product=xHCI Host Controller
S: SerialNumber=xhci-hcd.1.auto
C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms
```
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