Hi Laurent,
On 10/4/07, Laurent Pinchart <[EMAIL PROTECTED]> wrote:
> Hi Ben,
>
> On Wednesday 03 October 2007, Ben Lau wrote:
> > Hi,
> >
> > I have VGear Talkcam MX6 EZ and Talkcam MX6 AF. In low light
> > environment, both of the webcam drop frame rate from 25fps to 12fps
> > (or even lower) automatically. Can I forbid the camera to drop frame
> > through the UVC driver?
>
> I'm afraid not. Your webcams default to automatic exposure mode, which is
> allowed to lower the frame rate in low light conditions. You would need to
> switch to manual exposure mode, but that doesn't seem to be possible with the
> VGear Talkcam MX6.
>
> To confirm this (or to prove me wrong :-)), have a look at the USB descriptors
> with lsusb -v (usbutils 0.72 or newer). If the Input Terminal
> has "Auto-Exposure Mode" and "Exposure Time (Absolute)" controls, then you
> will be able to switch to manual exposure. Otherwise, you're stuck with lower
> frame rates.
I can't prove you are wrong... the result of lsusb show none of
control related to auto-exposure and exposure time.
Thanks for reply.
>
> > p.s Do the Creative Live! Optia has the same problem?
>
> I'm not sure if the webcam will lower the frame rate, but it supports manual
> exposure so you should be safe.
>
> > The available control of the camera:
> >
> > $ luvcview -f yuv -l
> > luvcview version 0.2.1
> > Video driver: x11
> > A window manager is available
> > video /dev/video0
> > Available controls of device 'Camera 1' (Type 1=Integer 2=Boolean
> > 3=Menu 4=Button)
> > V4L2_CID_BASE (predefined controls):
> > index:9963776 name:Brightness type:1
> > min:-128 max:127 step:1 def:0 now:0
> > index:9963777 name:Contrast type:1 min:0
> > max:100 step:1 def:0 now:0
> > index:9963778 name:Saturation type:1 min:0
> > max:100 step:1 def:0 now:0
> > index:9963779 name:Hue type:1 min:-40
> > max:40 step:1 def:0 now:0
> > index:9963792 name:Gamma type:1 min:1
> > max:100 step:1 def:1 now:1
> > V4L2_CID_PRIVATE_BASE (driver specific controls):
> > index:134217728 name:Backlight Compensation type:1 min:0
> > max:1 step:1 def:0 now:0
> > index:134217729 name:Power Line Frequency type:3 min:0
> > max:2 step:1 def:1 now:1
> > Menu items:
> > index:0 name:Disabled
> > index:1 name:50 Hz
> > index:2 name:60 Hz
> > index:134217730 name:Sharpness type:1 min:0
> > max:100 step:1 def:0 now:0
>
> Best regards,
>
> Laurent Pinchart
>
Bus 005 Device 012: ID 0c45:62c0 Microdia
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 Common Class
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
idVendor 0x0c45 Microdia
idProduct 0x62c0
bcdDevice 1.00
iManufacturer 2 Sonix Technology Co., Ltd.
iProduct 1 USB 2.0 Camera
iSerial 3 SN0001
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 753
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 1 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 1 USB 2.0 Camera
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 77
dwClockFrequency 6.000000MHz
bInCollection 1
baInterfaceNr( 0) 1
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 2
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 4
iTerminal 0
VideoControl Interface Descriptor:
bLength 26
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 4
guidExtensionCode {28f03370-6311-4a2e-ba2c-6890eb334016}
bNumControl 1
bNrPins 1
baSourceID( 0) 3
bControlSize 1
bmControls( 0) 0x01
iExtension 0
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 3
bSourceID 1
wMaxMultiplier 0
bControlSize 2
bmControls 0x0000053f
Brightness
Contrast
Hue
Saturation
Sharpness
Gamma
Backlight Compensation
Power Line Frequency
iProcessing 0
bmVideoStandards 0x6f
None
NTSC - 525/60
PAL - 625/50
SECAM - 625/50
PAL - 525/60
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 14
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormarts 1
wTotalLength 33025
bEndPointAddress 0
bmInfo 2
bTerminalLink 2
bStillCaptureMethod 1
bTriggerSupport 0
bTriggerUsage 1
bControlSize 1
bmaControls( 0) 27
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED)
bFormatIndex 1
bNumFrameDescriptors 7
guidFormat
{32595559-0000-0010-8000-00aa00389b71}
bBitsPerPixel 16
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 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 614400
dwMaxBitRate 18432000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 500000
dwFrameInterval( 2) 666666
dwFrameInterval( 3) 1000000
dwFrameInterval( 4) 2000000
dwFrameInterval( 5) 10000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 202752
dwMaxBitRate 6082560
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 500000
dwFrameInterval( 2) 666666
dwFrameInterval( 3) 1000000
dwFrameInterval( 4) 2000000
dwFrameInterval( 5) 10000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 153600
dwMaxBitRate 4608000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 500000
dwFrameInterval( 2) 666666
dwFrameInterval( 3) 1000000
dwFrameInterval( 4) 2000000
dwFrameInterval( 5) 10000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 176
wHeight 144
dwMinBitRate 50688
dwMaxBitRate 1520640
dwMaxVideoFrameBufferSize 50688
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 500000
dwFrameInterval( 2) 666666
dwFrameInterval( 3) 1000000
dwFrameInterval( 4) 2000000
dwFrameInterval( 5) 10000000
VideoStreaming Interface Descriptor:
bLength 50
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 160
wHeight 120
dwMinBitRate 38400
dwMaxBitRate 1152000
dwMaxVideoFrameBufferSize 38400
dwDefaultFrameInterval 333333
bFrameIntervalType 6
dwFrameInterval( 0) 333333
dwFrameInterval( 1) 500000
dwFrameInterval( 2) 666666
dwFrameInterval( 3) 1000000
dwFrameInterval( 4) 2000000
dwFrameInterval( 5) 10000000
VideoStreaming Interface Descriptor:
bLength 38
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 6
bmCapabilities 0x00
Still image unsupported
wWidth 1280
wHeight 960
dwMinBitRate 2457600
dwMaxBitRate 22118400
dwMaxVideoFrameBufferSize 2457600
dwDefaultFrameInterval 1111111
bFrameIntervalType 3
dwFrameInterval( 0) 1111111
dwFrameInterval( 1) 2000000
dwFrameInterval( 2) 10000000
VideoStreaming Interface Descriptor:
bLength 38
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 7
bmCapabilities 0x00
Still image unsupported
wWidth 1280
wHeight 1024
dwMinBitRate 2621440
dwMaxBitRate 23592960
dwMaxVideoFrameBufferSize 2621440
dwDefaultFrameInterval 1111111
bFrameIntervalType 3
dwFrameInterval( 0) 1111111
dwFrameInterval( 1) 2000000
dwFrameInterval( 2) 10000000
VideoStreaming Interface Descriptor:
bLength 34
bDescriptorType 36
bDescriptorSubtype 3 (STILL_IMAGE_FRAME)
bEndpointAddress 0
bNumImageSizePatterns 7
wWidth( 0) 1280
wHeight( 0) 1024
wWidth( 1) 1280
wHeight( 1) 960
wWidth( 2) 640
wHeight( 2) 480
wWidth( 3) 352
wHeight( 3) 288
wWidth( 4) 320
wHeight( 4) 240
wWidth( 5) 176
wHeight( 5) 144
wWidth( 6) 160
wHeight( 6) 120
bNumCompressionPatterns 7
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 0x0100 1x 256 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 0x0320 1x 800 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 0x0b20 2x 800 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 0x1320 3x 800 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 0x13e8 3x 1000 bytes
bInterval 1
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 2
bInterfaceCount 2
bFunctionClass 1 Audio
bFunctionSubClass 0
bFunctionProtocol 0
iFunction 4 USB Microphone
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 0
iInterface 4 USB Microphone
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 1.00
wTotalLength 39
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 0x0000
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 6 (FEATURE_UNIT)
bUnitID 2
bSourceID 1
bControlSize 2
bmaControls( 0) 0x03
bmaControls( 0) 0x00
Mute
Volume
iFeature 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 2
iTerminal 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 3
bDelay 1 frames
wFormatTag 1 PCM
AudioStreaming Interface Descriptor:
bLength 29
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 7 Discrete
tSamFreq[ 0] 8000
tSamFreq[ 1] 11025
tSamFreq[ 2] 16000
tSamFreq[ 3] 22050
tSamFreq[ 4] 24000
tSamFreq[ 5] 44100
tSamFreq[ 6] 48000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x0190 1x 400 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0 Undefined
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 Common Class
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
bNumConfigurations 1
Device Status: 0x0000
(Bus Powered)
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