Hi Laurent, all,
That's interesting about the timestamps, I though they were supposed to be
essential for synchronising audio and video properly. I'm not using audio
myself so not too concerned about that side of things. Also, there was a
small footnote on one of the msdn pages about interlacing requiring
timestamps so I had tried that for make interlacing work...it didn't work
and interlacing still isn't working properly so I stripped out oll the
interlacing descriptors and I'm going to do deinterlacing manually now
anyway because I need to do frame grabbing to disk so having proper video
card deinterlacing wouldn't help much anyway.
I think I may have found the source of my fps problems however, my frame is
768 x576, and as a point of convenience I found that sending 4 lines in a
uvc packet seemed to work just fine. 4 x 768 + 12 (header) turns out to be
1028 x 3 isoc usb packets, which is obviously more than you're allowed, but
because it was showing the picture just fine I thought it was ok.
Cropping the image to a smaller width though, and making the usb packets
smaller, seems to fix the frame rate in windows. It seems that while the usb
stack can handle the larger isoc packets, there's some buffering in the uvc
driver that's not large enough to work. I still need to do more testing to
confirm that's the root of the problem however. That's actually what that
other message I sent here by mistake was about, I meant to send it to the
lpc3000 group, I need a lot more buffering in chip to get my usb packet
sizes back down to legit sizes. I'll let you all know if I get it sorted
out, because it's a pretty deceptive problem, and highlights a way your
linux driver handles dodgy hardware better!
lsusb:
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 ?
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
idVendor 0x9999
idProduct 0x8000
bcdDevice 1.00
iManufacturer 1 xxxx
iProduct 2 xxx
iSerial 3 DEMO12345678
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 198
bNumInterfaces 2
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xc0
Self Powered
MaxPower 100mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 2 xxx
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 0
iInterface 2 xxx
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 50
dwClockFrequency 6.000000MHz
bInCollection 1
baInterfaceNr( 0) 1
VideoControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Camera Sensor
bAssocTerminal 0
iTerminal 0
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 2
bmControls 0x00000000
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 5
iTerminal 0
VideoControl Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 5 (PROCESSING_UNIT)
Warning: Descriptor too short
bUnitID 5
bSourceID 1
wMaxMultiplier 0
bControlSize 2
bmControls 0x0000001f
Brightness
Contrast
Hue
Saturation
Sharpness
iProcessing 0
bmVideoStandards 0x 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 8
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)
bNumFormats 1
wTotalLength 79
bEndPointAddress 131
bmInfo 0
bTerminalLink 3
bStillCaptureMethod 0
bTriggerSupport 0
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 27
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED)
bFormatIndex 1
bNumFrameDescriptors 1
guidFormat
{59555932-0000-1000-8000-00aa00389b71}
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 38
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 768
wHeight 576
dwMinBitRate 197376000
dwMaxBitRate 197376000
dwMaxVideoFrameBufferSize 884736
dwDefaultFrameInterval 400000
bFrameIntervalType 0
dwMinFrameInterval 400000
dwMaxFrameInterval 10000000
dwFrameIntervalStep 1
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 0x83 EP 3 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x1404 3x 1028 bytes
bInterval 1
-----Original Message-----
From: Laurent Pinchart [mailto:laurent.pinch...@ideasonboard.com]
Sent: Monday, 13 September 2010 8:48 AM
To: linux-uvc-devel@lists.berlios.de
Cc: Andrew Leech
Subject: Re: [Linux-uvc-devel] Slow frame rate windows/linux?
----
> I feel there must be something wrong in my uvc descriptors / setup
> that is confusing the windows driver where the linux one is more
> forgiving. I've tried playing with the mix/max bitrates, and
> continuous vs static frame intervals, all to no avail.
If you post the output of lsusb -v I could check the descriptors.
> I've also added timestamps to my frames (uncompressed yuy2) which I
> think are working, but also noticed no difference.
>
> Is there any way with the linux driver to check the frame timestamps,
> if they're wrong it should show up as late/missed frames?
The uvcvideo driver ignores timestamps at the moment;
> Has anyone got any suggestions? I really want to ensure my hardware is
> going to be stable on as wide a range of computers as possible.
--
Regards,
Laurent Pinchart
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