USB 2.0 bandwidth bug in XP SP2?

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I have received some complaints about their USB audio speaker/mic is not
working properly with their USB webcam.
I did some tests and find there may be a bug in XP SP2 on how USB 2.0
(high-speed) bandwidth is handled, here is my configuration:
- P4 2.26GHz XP SP2 PC with high-speed USB port.
- D link USB 2.0 hub connect to the PC USB 2.0 port.
- Logitech QuickCam Pro 4000 connected to one port on the hub.(full speed
camera)
- A USB audio device (with built-in mic and speaker) to one of port on the
hub.
- And make sure the USB mic and speaker is Windows’ default audio devices.
- Run an application to make sure the camera is streaming video.
- Run Windows Media Player to play a song on the USB audio speaker, most of
the time Media Player gives an error message, says there is something wrong
with the audio device.

When I go to Device manager checked the USB bandwidth usages, I have noticed
the camera is using 75% bandwidth, and USB audio mic/speaker could use 35%
when both running(turn off the camera), and system reserves 12%.
When a high speed USB camera is used, the XP shows USB bandwidth usage 399%
???(not a typo, it’s 399%).

According to the USB 2.0 specification, the high-speed 2.0 hub and the host
pc should be a high-speed link, and the high-speed hub should be able handle
many full speed devices at the same time, not just one full speed camera.

I also checked the HUB with a USB 2.0 analyzer which shows the link is high
speed, then I’m suspecting is XP SP2 which may have flaws in handle USB 2.0
bandwidth allocation:
1. The 399% bandwidth usage seems wrong.
2. Other Windows driver, such as USBAudio driver may check the bandwidth
base on not exceeding 100%.

User may also see a message that says “Out of USB Bandwidthâ€.

That sounds like a big problem, I thought there must be a KB to talk about
this, but I could not find one.

Have you seen this? any comments?

Thanks!
 
Each port on the mobo/internal card in the computer can
handle up to 480 mbps [real life a little less] but you have
connected everything to your hub on one port, all the USB
connectors on the hub are sharing the power and the
bandwidth. This is not a problem with low bandwidth devices
such as mice, keyboards and even flash memory, but your
video and audio need real-time through-put.
Use the hub for less demanding devices and connect the
camera and speakers to the computer directly, or get another
hub that connects to another port on the mobo/computer.

Be sure to get powered hubs.



|I have received some complaints about their USB audio
speaker/mic is not
| working properly with their USB webcam.
| I did some tests and find there may be a bug in XP SP2 on
how USB 2.0
| (high-speed) bandwidth is handled, here is my
configuration:
| - P4 2.26GHz XP SP2 PC with high-speed USB port.
| - D link USB 2.0 hub connect to the PC USB 2.0 port.
| - Logitech QuickCam Pro 4000 connected to one port on the
hub.(full speed
| camera)
| - A USB audio device (with built-in mic and speaker) to
one of port on the
| hub.
| - And make sure the USB mic and speaker is Windows'
default audio devices.
| - Run an application to make sure the camera is streaming
video.
| - Run Windows Media Player to play a song on the USB audio
speaker, most of
| the time Media Player gives an error message, says there
is something wrong
| with the audio device.
|
| When I go to Device manager checked the USB bandwidth
usages, I have noticed
| the camera is using 75% bandwidth, and USB audio
mic/speaker could use 35%
| when both running(turn off the camera), and system
reserves 12%.
| When a high speed USB camera is used, the XP shows USB
bandwidth usage 399%
| ???(not a typo, it's 399%).
|
| According to the USB 2.0 specification, the high-speed 2.0
hub and the host
| pc should be a high-speed link, and the high-speed hub
should be able handle
| many full speed devices at the same time, not just one
full speed camera.
|
| I also checked the HUB with a USB 2.0 analyzer which shows
the link is high
| speed, then I'm suspecting is XP SP2 which may have flaws
in handle USB 2.0
| bandwidth allocation:
| 1. The 399% bandwidth usage seems wrong.
| 2. Other Windows driver, such as USBAudio driver may check
the bandwidth
| base on not exceeding 100%.
|
| User may also see a message that says "Out of USB
Bandwidth".
|
| That sounds like a big problem, I thought there must be a
KB to talk about
| this, but I could not find one.
|
| Have you seen this? any comments?
|
| Thanks!
|
 
Jim,
Thank you for your response.
What you suggested can resolve this problem, indeed I suggested our
customers to just do that: plug the camera and usb audio device to a
different USB port on the PC not all into one hub.
But, my point is why need to do that? A high-speed hub should be able to
handle multiple full speed device.

I tried the same configuration on Windows Vista Beta build 5472, which works
fine: the camera is using 4% while it capturing video, and the USB audio
device capturing audio uses 1% usb bandwidth.

It seems to me, this is a XP SP2 bug.

Any thoughts?


Jim Macklin said:
Each port on the mobo/internal card in the computer can
handle up to 480 mbps [real life a little less] but you have
connected everything to your hub on one port, all the USB
connectors on the hub are sharing the power and the
bandwidth. This is not a problem with low bandwidth devices
such as mice, keyboards and even flash memory, but your
video and audio need real-time through-put.
Use the hub for less demanding devices and connect the
camera and speakers to the computer directly, or get another
hub that connects to another port on the mobo/computer.

Be sure to get powered hubs.



|I have received some complaints about their USB audio
speaker/mic is not
| working properly with their USB webcam.
| I did some tests and find there may be a bug in XP SP2 on
how USB 2.0
| (high-speed) bandwidth is handled, here is my
configuration:
| - P4 2.26GHz XP SP2 PC with high-speed USB port.
| - D link USB 2.0 hub connect to the PC USB 2.0 port.
| - Logitech QuickCam Pro 4000 connected to one port on the
hub.(full speed
| camera)
| - A USB audio device (with built-in mic and speaker) to
one of port on the
| hub.
| - And make sure the USB mic and speaker is Windows'
default audio devices.
| - Run an application to make sure the camera is streaming
video.
| - Run Windows Media Player to play a song on the USB audio
speaker, most of
| the time Media Player gives an error message, says there
is something wrong
| with the audio device.
|
| When I go to Device manager checked the USB bandwidth
usages, I have noticed
| the camera is using 75% bandwidth, and USB audio
mic/speaker could use 35%
| when both running(turn off the camera), and system
reserves 12%.
| When a high speed USB camera is used, the XP shows USB
bandwidth usage 399%
| ???(not a typo, it's 399%).
|
| According to the USB 2.0 specification, the high-speed 2.0
hub and the host
| pc should be a high-speed link, and the high-speed hub
should be able handle
| many full speed devices at the same time, not just one
full speed camera.
|
| I also checked the HUB with a USB 2.0 analyzer which shows
the link is high
| speed, then I'm suspecting is XP SP2 which may have flaws
in handle USB 2.0
| bandwidth allocation:
| 1. The 399% bandwidth usage seems wrong.
| 2. Other Windows driver, such as USBAudio driver may check
the bandwidth
| base on not exceeding 100%.
|
| User may also see a message that says "Out of USB
Bandwidth".
|
| That sounds like a big problem, I thought there must be a
KB to talk about
| this, but I could not find one.
|
| Have you seen this? any comments?
|
| Thanks!
|
Click to expand...
 
If you connect a 3/4 inch garden hose to a faucet at 45 PSI
pressure and open the valve wide open, you'll get a maximum
of say, 50 gallons a minute flow from a 25 foot hose. If
you add 200 feet of 3/4 inch hose the flow will be reduced
to maybe 5 gallons a minute. If you make a manifold from
brass pipe (a hub) and connect five 3/4 inch 10 foot hoses
you won't get 250 gallons total flow, you won't get even the
50 gallons, same sort of thing happens with electricity and
USB, each port has a maximum rate, each device has a maximum
rate, when you exceed the available "pipe capacity" you get
broken and reduced flow of water or signals. Also, a
computer has buffers and must process the data to get an
output. If you empty the buffer with a fast processor, the
buffer must fill up again before the signal will be output
[watch streaming video load, there may be settings in your
computer for buffers, virtual memory and CPU priority that
are causing the problem. I can't say more than that.

A hub can certainly handle input and output, but can't do
more than the single hub that is in use on the mobo.


| Jim,
| Thank you for your response.
| What you suggested can resolve this problem, indeed I
suggested our
| customers to just do that: plug the camera and usb audio
device to a
| different USB port on the PC not all into one hub.
| But, my point is why need to do that? A high-speed hub
should be able to
| handle multiple full speed device.
|
| I tried the same configuration on Windows Vista Beta build
5472, which works
| fine: the camera is using 4% while it capturing video, and
the USB audio
| device capturing audio uses 1% usb bandwidth.
|
| It seems to me, this is a XP SP2 bug.
|
| Any thoughts?
|
|
| "Jim Macklin" wrote:
|
| > Each port on the mobo/internal card in the computer can
| > handle up to 480 mbps [real life a little less] but you
have
| > connected everything to your hub on one port, all the
USB
| > connectors on the hub are sharing the power and the
| > bandwidth. This is not a problem with low bandwidth
devices
| > such as mice, keyboards and even flash memory, but your
| > video and audio need real-time through-put.
| > Use the hub for less demanding devices and connect the
| > camera and speakers to the computer directly, or get
another
| > hub that connects to another port on the mobo/computer.
| >
| > Be sure to get powered hubs.
| >
| >
| >
| >
| > |I have received some complaints about their USB audio
| > speaker/mic is not
| > | working properly with their USB webcam.
| > | I did some tests and find there may be a bug in XP SP2
on
| > how USB 2.0
| > | (high-speed) bandwidth is handled, here is my
| > configuration:
| > | - P4 2.26GHz XP SP2 PC with high-speed USB port.
| > | - D link USB 2.0 hub connect to the PC USB 2.0 port.
| > | - Logitech QuickCam Pro 4000 connected to one port on
the
| > hub.(full speed
| > | camera)
| > | - A USB audio device (with built-in mic and speaker)
to
| > one of port on the
| > | hub.
| > | - And make sure the USB mic and speaker is Windows'
| > default audio devices.
| > | - Run an application to make sure the camera is
streaming
| > video.
| > | - Run Windows Media Player to play a song on the USB
audio
| > speaker, most of
| > | the time Media Player gives an error message, says
there
| > is something wrong
| > | with the audio device.
| > |
| > | When I go to Device manager checked the USB bandwidth
| > usages, I have noticed
| > | the camera is using 75% bandwidth, and USB audio
| > mic/speaker could use 35%
| > | when both running(turn off the camera), and system
| > reserves 12%.
| > | When a high speed USB camera is used, the XP shows USB
| > bandwidth usage 399%
| > | ???(not a typo, it's 399%).
| > |
| > | According to the USB 2.0 specification, the high-speed
2.0
| > hub and the host
| > | pc should be a high-speed link, and the high-speed hub
| > should be able handle
| > | many full speed devices at the same time, not just one
| > full speed camera.
| > |
| > | I also checked the HUB with a USB 2.0 analyzer which
shows
| > the link is high
| > | speed, then I'm suspecting is XP SP2 which may have
flaws
| > in handle USB 2.0
| > | bandwidth allocation:
| > | 1. The 399% bandwidth usage seems wrong.
| > | 2. Other Windows driver, such as USBAudio driver may
check
| > the bandwidth
| > | base on not exceeding 100%.
| > |
| > | User may also see a message that says "Out of USB
| > Bandwidth".
| > |
| > | That sounds like a big problem, I thought there must
be a
| > KB to talk about
| > | this, but I could not find one.
| > |
| > | Have you seen this? any comments?
| > |
| > | Thanks!
| > |
| >
| >
| >
 
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