Re: [Linux-uvc-devel] Problem with webcam: 18ec:3288 (Arkmikro chipset)

[Laurent P. <lau...@sk...>]

On Monday 29 December 2008, K wrote:
> Hi Laurent,
>
> I tried the quirks=2 settings. The loading looks better but Motion returns
> a 640x480 picture whose content is completely black. It seems the Jpeg
> format used by this webcam is not supported. Ok, here we go:
>
> I tried all of this with "echo 2 > ... quirks"
>
> dmesg:
>
> uvcvideo 4-2:1.0: usb_probe_interface
> uvcvideo 4-2:1.0: usb_probe_interface - got id
> uvcvideo: Found UVC 1.00 device USB2.0 PC CAMERA (18ec:3288)
> uvcvideo: Forcing device quirks 0x2 by module parameter for testing
> purpose. uvcvideo: Please report required quirks to the linux-uvc-devel
> mailing list. uvcvideo: UVC non compliance - GET_DEF(PROBE) not supported.
> Enabling workaround.
> input: USB2.0 PC CAMERA as /class/input/input28
> uhci_hcd 0000:00:09.1: reserve dev 7 ep81-INT, period 8, phase 4, 23 us
> usb 4-2: adding 4-2:1.1 (config #1, interface 1)
> usb 4-2:1.1: uevent
> drivers/usb/core/inode.c: creating file '007'
> usb 4-2: New USB device found, idVendor=18ec, idProduct=3288
> usb 4-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
> usb 4-2: Product: USB2.0 PC CAMERA
> usb 4-2: Manufacturer: ARKMICRO
>
> Motion complains about the Jpeg format. I captured the binary stream of a
> single frame using "./capture_example -d /dev/video2 -c 1 -o > vid2.dump".
> This file has been attached to this mail, watching with an hexa editor, it
> actually doesn't look like Jpeg as there is not 'JFIF' string inside.

If you skip the first 13 bytes (that surprisingly look like a possibly valid 
UVC header), the remaining data make a valid JPEG frame except for the lack 
of JFIF marker. I can see why applications would have trouble decoding that. 
Could you please capture a few consecutive frames and send them to me ? I'd 
like to have a look at the header.

> [1] Thread 1 started
> [1] cap.driver: "uvcvideo"
> [1] cap.card: "USB2.0 PC CAMERA"
> [1] cap.bus_info: "0000:00:09.1"
> [1] cap.capabilities=0x04000001
> [1] - VIDEO_CAPTURE
> [1] - STREAMING
> [1] Supported palettes:
> [1] 0: MJPG (MJPEG)
> [1] index_format 2 Test palette MJPG (640x480)
> [1] Using palette MJPG (640x480) bytesperlines 0 sizeimage 614400
> colorspace 00000000
> [1] VIDIOC_G_JPEGCOMP not supported but it should be (does your webcam
> driver support this ioctl?)
> [1] found control 0x00980900, "Brightness", range 0,255
> [1]     "Brightness", default 123, current 123
> [1] found control 0x00980901, "Contrast", range 0,255
> [1]     "Contrast", default 160, current 160
> [1] found control 0x00980902, "Saturation", range 0,255
> [1]     "Saturation", default 140, current 140
> [1] found control 0x00980903, "Hue", range -128,127
> [1]     "Hue", default 0, current 0
> [1] found control 0x00980910, "Gamma", range 1,16
> [1]     "Gamma", default 8, current 8
> [1] found control 0x00980913, "Gain", range 0,65535
> [1]     "Gain", default 16, current 0
> [1] mmap information:
> [1] frames=4
> [1] 0 length=614400
> [1] 1 length=614400
> [1] 2 length=614400
> [1] 3 length=614400
> [1] Using V4L2
> [1] Resizing pre_capture buffer to 1 items
> Not a JPEG file: starts with 0xb2 0x10
> [1] Resizing pre_capture buffer to 3 items
> Not a JPEG file: starts with 0x55 0x9b
> [1] Started stream webcam server in port 8082
> Corrupt JPEG data: 1 extraneous bytes before marker 0xd9

Best regards,

Laurent Pinchart