Do USB Devices require more CPU Power to operate them?

[jksmurf]

The reason I ask is because I have a PVR-150MCE (internal) and a Lifeview TVWalker Mini (USB2.0).

When I run GBPVR with BOTH devices installed (and using the Lifeview device to record - I checked the tray status), GBPVR invariably crashes (on the PC or MVP, it doesn't matter), particularly when it is "recording" LiveTV on the USB device.

If I remove the Lifeview device and run ONLY the PVR150, the GBPVR setup is stable as a rock. I have tried multiple combinations of Codecs and Muxes with the Lifeview device installed, as I thought "this must be Codec related". (The Lifeview device works OK through its native TVR, when that alone is used).

It's not that it doesn't work at all, it works for a little while, then (normally after trying to change channels), just gets "stuck" (freezes) on teh TV Window or MVP, although the green icon just goes on showing "recording"....

Before I spring for a 2nd PVR-150 card (to keep my wife happy, she is tiring of my nocturnal attempts to get it to work) is it likely that the USB2 device is simply asking too much of my system?

ASUS TUSL2-C Tualatin 1.2GHZ CPU
512MB Ram
350W Power Supply

[blader_se]

It does require more power, don't know if the TVWalker have an external power supply or not.
You can check the power demands on any USB port in Windows XP by right-clicking My Computer and choosing Properties, Hardware, Device Manager. Double-click Universal Serial Bus controllers, double-click the USB Root Hub entry, choose the Power tab, and add up the amounts in the 'Power Required' column.

Sorry, I missed the "CPU" word in your question...

[stefan]

Sorry, I missed the "CPU" word in your question...

LOL

[andlju]

I think it all depends on whether or not the USB tuner has a hardware encoder or not. As far as I can tell, your device SHOULD have an encoder on it (that even does MPEG4..?) so I can't really see why your CPU would be much affected.

I have an old Centrino laptop with an Hauppauge WinTv PVR USB2 card (hardware MPEG2-encoder), and the only way I can tell that it is recording is that the harddrive light flashes once every second. The CPU seems almost unaffected..

[jksmurf]

Cheers fellers,

Yes it does have hardware encoding, MPEG2/MPEG4 included, the latter which I do not (did not) use anyway as I mainly view over MVP and there is no point transcoding.

Maybe one of these days I'll buy a new PC and try it again (try codecs again in a few months), but at the moment it's just ending in tears with that device :-).

k.

[gimble]

From my experience:

USB devices ( vs internal devices ) can have a variety of effects on a system. Granted, my experience is with externally attached drives in most cases, but in general I've learned to keep in mind the following considerations:

1) Timing issues. The extra latency involved with routing commands through a driver, to an external box, and then receiving data appropriately can cause timing issues if a driver ( or software package ) is timing-sensitive. For example, if the USB driver is not releasing control back to the OS quickly enough, and another device driver ( Hauppauge 150, for example ) can't get a timeslot to do some critical things, bad things can happen.

2) Bus contention issues. With USB, it's possible that the bus can be overloaded if there are multiple devices contending to send and receive data back and forth. Even seemingly innocent things like mice can cause problems in the wrong situation.

3) Cable problems. A poorly shielded USB cable can cause lots of interference and unreliable results to an external USB device. A poor device driver may not be able to handle unusual results in some cases.

Note in all of the above, it's not a lack of CPU performance that cripples the system, but rather interactions between the electrical systems and/or the device drivers.

In short, I use (and enjoy) USB-attached storage devices since they seem to finally be pretty reliable, but in general I don't like USB-attached devices more complicated than a mouse or keyboard. They've just caused me more headaches than they're worth.

[jksmurf]

Cheers Gimble,

Interesting summary.

k.