Hi!,

Thanks Hans for starting this, and hi Laurent.

On Wed, Jul 11, 2018 at 1:00 PM, Laurent Pinchart
<laurent.pinch...@ideasonboard.com> wrote:
> Hi Hans,
>
> On Wednesday, 11 July 2018 11:37:14 EEST Hans de Goede wrote:
>> Hi Laurent,
>>
>> At Guadec Carlos (in the Cc) told me that on his Acer 2-in-1 only
>> the frontcam is working and it seems both are represented by a
>> single UVC USB device. I've told him to check for some v4l control
>> to flip between front and back.
>>
>> Carlos, as I mentioned you can try gtk-v4l
>> ("sudo dnf install gtk-v4l") or qv4l2
>> ("sudo dnf install qv4l2") these will both show
>> you various controls for the camera. One of those might do the trick.
>>
>> But I recently bought a 2nd second hand Cherry Trail based HP
>> X2 2-in-1 and much to my surprise that is actually using an UVC
>> cam, rather then the usual ATOMISP crap and it has the same issue.
>>
>> This device does not seem to have a control to flip between the
>> 2 cams, instead it registers 2 /dev/video? nodes but the second
>> node does not work
>
> The second node is there to expose metadata to userspace, not image data.
> That's a recent addition to the uvcvideo driver.
>
>> and dmesg contains:
>>
>> [   26.079868] uvcvideo: Found UVC 1.00 device HP TrueVision HD (05c8:03a3)
>> [   26.095485] uvcvideo 1-4.2:1.0: Entity type for entity Extension 4 was
>> not initialized!
>> [   26.095492] uvcvideo 1-4.2:1.0: Entity type for entity Processing 2 was
>> not initialized!
>> [   26.095496] uvcvideo 1-4.2:1.0: Entity type for entity Camera 1 was not
>> initialized!
>
> You can safely ignore those messages. I need to submit a patch to get rid of
> them.
>
>> Laurent, I've attached lsusb -v output so that you can check the
>> descriptors.
>
> Thank you.
>
> It's funny how UVC specifies a standard way to describe a device with two
> camera sensors with dynamic selection of one of them at runtime, and vendors
> instead implement vendor-specific crap :-(
>
> The interesting part in the descriptors is
>
>       VideoControl Interface Descriptor:
>         bLength                27
>         bDescriptorType        36
>         bDescriptorSubtype      6 (EXTENSION_UNIT)
>         bUnitID                 4
>         guidExtensionCode         {1229a78c-47b4-4094-b0ce-db07386fb938}
>         bNumControl             2
>         bNrPins                 1
>         baSourceID( 0)          2
>         bControlSize            2
>         bmControls( 0)       0x00
>         bmControls( 1)       0x06
>         iExtension              0
>
> The extension unit exposes two controls (bmControls is a bitmask). They can be
> accessed from userspace through the UVCIOC_CTRL_QUERY ioctl, or mapped to V4L2
> controls through the UVCIOC_CTRL_MAP ioctl, in which case they will be exposed
> to standard V4L2 applications.
>
> If you want to experiment with this, I would advise querying both controls
> with UVCIOC_CTRL_QUERY. You can use the UVC_GET_CUR, UVC_GET_MIN, UVC_GET_MAX,
> UVC_GET_DEF and UVC_GET_RES requests to get the control current, minimum,
> maximum, default and resolution values, and UVC_GET_LEN and UVC_GET_INFO to
> get the control size (in bytes) and flags. Based on that you can start
> experimenting with UVC_SET_CUR to set semi-random values.
>
> I'm however worried that those two controls would be a register address and a
> register value, for indirect access to all hardware registers in the device.
> In that case, you would likely need information from the device vendor, or
> possibly a USB traffic dump from a Windows machine when switching between the
> front and back cameras.
>
>> Carlos, it might be good to get Laurent your descriptors too, to do
>> this do "lsusb", note what is the <vid>:<pid> for your camera and then
>> run:
>>
>> sudo lsusb -v -d <vid>:<pid>  > lsusb.log
>>
>> And send Laurent a mail with the generated lsusb
>
> That would be appreciated, but I expect the same issue :-(

Please find it attached. IIUC your last email, it might not be the
exact same issue, but you can definitely judge better.

Cheers,
  Carlos
Bus 001 Device 004: ID 0bda:56c1 Realtek Semiconductor Corp. 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x0bda Realtek Semiconductor Corp.
  idProduct          0x56c1 
  bcdDevice            0.16
  iManufacturer           3 Pegatron
  iProduct                1 USB Camera
  iSerial                 2 0x0001
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          963
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          4 USB Camera
    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               5 USB Camera
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      1 Video Control
      bInterfaceProtocol      0 
      iInterface              5 USB Camera
      VideoControl Interface Descriptor:
        bLength                13
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdUVC               1.00
        wTotalLength          107
        dwClockFrequency       15.000000MHz
        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           0x0000200e
          Auto-Exposure Mode
          Auto-Exposure Priority
          Exposure Time (Absolute)
          Roll (Absolute)
      VideoControl Interface Descriptor:
        bLength                11
        bDescriptorType        36
        bDescriptorSubtype      5 (PROCESSING_UNIT)
      Warning: Descriptor too short
        bUnitID                 2
        bSourceID               1
        wMaxMultiplier          0
        bControlSize            2
        bmControls     0x0000177f
          Brightness
          Contrast
          Hue
          Saturation
          Sharpness
          Gamma
          White Balance Temperature
          Backlight Compensation
          Gain
          Power Line Frequency
          White Balance Temperature, Auto
        iProcessing             0 
        bmVideoStandards     0x09
          None
          SECAM - 625/50
      VideoControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID             3
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bSourceID               6
        iTerminal               0 
      VideoControl Interface Descriptor:
        bLength                27
        bDescriptorType        36
        bDescriptorSubtype      6 (EXTENSION_UNIT)
        bUnitID                 4
        guidExtensionCode         {1229a78c-47b4-4094-b0ce-db07386fb938}
        bNumControl             2
        bNrPins                 1
        baSourceID( 0)          2
        bControlSize            2
        bmControls( 0)       0x00
        bmControls( 1)       0x06
        iExtension              0 
      VideoControl Interface Descriptor:
        bLength                29
        bDescriptorType        36
        bDescriptorSubtype      6 (EXTENSION_UNIT)
        bUnitID                 6
        guidExtensionCode         {26b8105a-0713-4870-979d-da79444bb68e}
        bNumControl             9
        bNrPins                 1
        baSourceID( 0)          4
        bControlSize            4
        bmControls( 0)       0x1f
        bmControls( 1)       0x01
        bmControls( 2)       0x38
        bmControls( 3)       0x00
        iExtension              6 Realtek Extended Controls Unit
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0010  1x 16 bytes
        bInterval               6
    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                      697
        bEndPointAddress                  129
        bmInfo                              0
        bTerminalLink                       3
        bStillCaptureMethod                 2
        bTriggerSupport                     1
        bTriggerUsage                       0
        bControlSize                        1
        bmaControls( 0)                     0
        bmaControls( 1)                     0
      VideoStreaming Interface Descriptor:
        bLength                            27
        bDescriptorType                    36
        bDescriptorSubtype                  4 (FORMAT_UNCOMPRESSED)
        bFormatIndex                        1
        bNumFrameDescriptors                9
        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                            34
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         1
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            640
        wHeight                           480
        dwMinBitRate                 73728000
        dwMaxBitRate                147456000
        dwMaxVideoFrameBufferSize      614400
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         2
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            640
        wHeight                           360
        dwMinBitRate                 55296000
        dwMaxBitRate                110592000
        dwMaxVideoFrameBufferSize      460800
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         3
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            160
        wHeight                           120
        dwMinBitRate                  4608000
        dwMaxBitRate                  9216000
        dwMaxVideoFrameBufferSize       38400
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        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                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        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                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         6
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            800
        wHeight                           600
        dwMinBitRate                 76800000
        dwMaxBitRate                 76800000
        dwMaxVideoFrameBufferSize      960000
        dwDefaultFrameInterval        1000000
        bFrameIntervalType                  1
        dwFrameInterval( 0)           1000000
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         7
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            960
        wHeight                           540
        dwMinBitRate                 82944000
        dwMaxBitRate                 82944000
        dwMaxVideoFrameBufferSize     1036800
        dwDefaultFrameInterval        1000000
        bFrameIntervalType                  1
        dwFrameInterval( 0)           1000000
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         8
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                           1280
        wHeight                           720
        dwMinBitRate                 73728000
        dwMaxBitRate                 73728000
        dwMaxVideoFrameBufferSize     1843200
        dwDefaultFrameInterval        2000000
        bFrameIntervalType                  1
        dwFrameInterval( 0)           2000000
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  5 (FRAME_UNCOMPRESSED)
        bFrameIndex                         9
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                           1600
        wHeight                          1200
        dwMinBitRate                 61440000
        dwMaxBitRate                 61440000
        dwMaxVideoFrameBufferSize     3840000
        dwDefaultFrameInterval        5000000
        bFrameIntervalType                  1
        dwFrameInterval( 0)           5000000
      VideoStreaming Interface Descriptor:
        bLength                            26
        bDescriptorType                    36
        bDescriptorSubtype                  3 (STILL_IMAGE_FRAME)
        bEndpointAddress                    0
        bNumImageSizePatterns               5
        wWidth( 0)                       1600
        wHeight( 0)                      1200
        wWidth( 1)                        160
        wHeight( 1)                       120
        wWidth( 2)                        320
        wHeight( 2)                       240
        wWidth( 3)                        640
        wHeight( 3)                       480
        wWidth( 4)                       1280
        wHeight( 4)                       720
        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))
      VideoStreaming Interface Descriptor:
        bLength                            11
        bDescriptorType                    36
        bDescriptorSubtype                  6 (FORMAT_MJPEG)
        bFormatIndex                        2
        bNumFrameDescriptors                9
        bFlags                              1
          Fixed-size samples: Yes
        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                            34
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         1
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            640
        wHeight                           480
        dwMinBitRate                 73728000
        dwMaxBitRate                147456000
        dwMaxVideoFrameBufferSize      614400
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         2
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            640
        wHeight                           360
        dwMinBitRate                 55296000
        dwMaxBitRate                110592000
        dwMaxVideoFrameBufferSize      460800
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         3
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            160
        wHeight                           120
        dwMinBitRate                  4608000
        dwMaxBitRate                  9216000
        dwMaxVideoFrameBufferSize       38400
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         4
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            352
        wHeight                           288
        dwMinBitRate                 24330240
        dwMaxBitRate                 48660480
        dwMaxVideoFrameBufferSize      202752
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            34
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         5
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            320
        wHeight                           240
        dwMinBitRate                 18432000
        dwMaxBitRate                 36864000
        dwMaxVideoFrameBufferSize      153600
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  2
        dwFrameInterval( 0)            333333
        dwFrameInterval( 1)            666666
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         6
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            800
        wHeight                           600
        dwMinBitRate                230400000
        dwMaxBitRate                230400000
        dwMaxVideoFrameBufferSize      960000
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  1
        dwFrameInterval( 0)            333333
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         7
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                            960
        wHeight                           540
        dwMinBitRate                248832000
        dwMaxBitRate                248832000
        dwMaxVideoFrameBufferSize     1036800
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  1
        dwFrameInterval( 0)            333333
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         8
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                           1280
        wHeight                           720
        dwMinBitRate                442368000
        dwMaxBitRate                442368000
        dwMaxVideoFrameBufferSize     1843200
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  1
        dwFrameInterval( 0)            333333
      VideoStreaming Interface Descriptor:
        bLength                            30
        bDescriptorType                    36
        bDescriptorSubtype                  7 (FRAME_MJPEG)
        bFrameIndex                         9
        bmCapabilities                   0x00
          Still image unsupported
        wWidth                           1600
        wHeight                          1200
        dwMinBitRate                921600000
        dwMaxBitRate                921600000
        dwMaxVideoFrameBufferSize     3840000
        dwDefaultFrameInterval         333333
        bFrameIntervalType                  1
        dwFrameInterval( 0)            333333
      VideoStreaming Interface Descriptor:
        bLength                            26
        bDescriptorType                    36
        bDescriptorSubtype                  3 (STILL_IMAGE_FRAME)
        bEndpointAddress                    0
        bNumImageSizePatterns               5
        wWidth( 0)                       1600
        wHeight( 0)                      1200
        wWidth( 1)                        160
        wHeight( 1)                       120
        wWidth( 2)                        320
        wHeight( 2)                       240
        wWidth( 3)                        640
        wHeight( 3)                       480
        wWidth( 4)                       1280
        wHeight( 4)                       720
        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     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0080  1x 128 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       2
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       3
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       4
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0b00  2x 768 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       5
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0c00  2x 1024 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       6
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x1380  3x 896 bytes
        bInterval               1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       7
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      2 Video Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x1400  3x 1024 bytes
        bInterval               1
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  bNumConfigurations      1
Device Status:     0x0000
  (Bus Powered)

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