Solved - Stutter / jerkiness on USB DVB-T (NZ)

[serafis]

Thought I'd post this in case anyone else has similar problems.

I was getting intermittent jerkiness / "micro-stuttering" of Freeview (H.264/HE-AAC) video and audio from a Hauppauge HVR-900 DVB-T USB stick, on both Live-TV and recordings. Since playback of downloaded Freeview TS samples was completely smooth with minimal CPU, I was pretty sure that it wasn't a codec or hardware acceleration problem.

After a lot (and I mean a lot!) of tweaking, I eventually put this down to signal quality causing dropped frames, as I have a number of splitters between my antenna and the tuner, no line-of-sight to the transmitter, and the symptoms were worse with HD channels.

I was about to give up on Freeview completely when I discovered I was also getting some similar symptoms (but not so bad) from the analog tuner, so I decided to investigate a bit further.

Turns out it really *does* matter which USB port the tuner is plugged into, what other USB devices are on the same internal hub and possibly what other PCI devices are on the same IRQ.

Of my eight USB motherboard ports (on 4 internal hubs), only one gives perfect playback and only then if the second port off that hub is unused or has something very low bandwidth and usage like a mouse plugged in (not the IR receiver!)

Of the other seven ports, quality ranges from slight intermittent hiccupping to completely unwatchable with picture freezes, breakup, pixellation and the dreaded green bars, depending on which port and which other devices are plugged in.

Also got the best results with PCI latency set to 32 in BIOS. Possibly something to do with USB polling, USB / USB-PCI bridge bandwidth, PCI BUS or virtual IRQ contention? Anyway, by trial and error unplugging USB devices and swapping them around, it finally seems to work perfectly on all analog and Freeview SD and HD channels.

[sub]

Great - glad you finally got to the bottom of it.

[DrSoftware]

Interesting I have exactly the same problem on two completely different PC's - both have Hauppauge Nova-T-500 PCI dual tuners. Unfortunately I don't have alot of options as to which PCI slots I use, I only have 2 to choose from in both PC's. Maybe I'll have a play sometime.

[griffy]

did you know that on many motherboards some of the USB ports are still USB 1 :eek:
I have 8 USB ports but only 4 are USB 2 and 4 are USB 1... :mad:
use your mouse/keyboard on the slow ones

[johnsonx42]

did you know that on many motherboards some of the USB ports are still USB 1 :eek:
I have 8 USB ports but only 4 are USB 2 and 4 are USB 1... :mad:
use your mouse/keyboard on the slow ones

I have never, ever seen such a thing. You may well have an odd-duck motherboard with that config (probably quite old), but it is certainly not 'many motherboards'. It's also possible you have some sort of driver or configuration problem causing one or more of the root hubs to not have an EHCI driver loaded. Or you just may be mistaken. Sorry if this seems like a flame, but there's just no way what you stated is even close to true.

[martint123]

both have Hauppauge Nova-T-500 PCI dual tuners.

Did you know these are USB devices - but with PCI to USB controllers on board?

[DrSoftware]

I figured that might be the case, I've seen them referenced in log files somewhere as USB devices.

[griffy]

Should have said many older motherboards had...

Sorry if this seems like a flame, but there's just no way what you stated is even close to true.

Flame all you want

http://forums.techarena.in/motherboard-p...166278.htm

Older PC's, made before 2005, have a combination of USB 1.1 and 2.0. the USB 1.1 ports are in the front, for easy connection to low power devices, such as keyboards, mice, and flash drives. The rear USB 2.0 ports are for high power devices, such as iPods, USB external hard disks, etc.

http://www.computing.net/answers/hardwar...54357.html

Some older mboards have some ports that support USB 1.1, some that support USB 2.0, which also supports USB 1.x, but newer mboards have ports that are only USB 2.0, which also supports USB 1.x.

http://www.viaarena.com/a-guide-to-under...4&MCatID=1

It is entirely possible for you to have USB 2.0 ports in the rear of the computer, but only USB 1.x ports in the front (or vice-versa).

[johnsonx42]

Fair enough, I stand corrected (sort of, two of three links are just someone else's opinion, and the third could just as easily be referring to on add-in card). I've still never seen it personally, and I've seen a whole lot of motherboards over the past 20 years. The only case where I've seen the USB 2.0/1.1 combination is where the mainboard supports only 1.1, but a 2.0 add-in card is installed (which of course could be done by the computer manufacturer).

All in all, my rant was probably unnecessary anyway. Peace.

[whurlston]

did you know that on many motherboards some of the USB ports are still USB 1 :eek:
I have 8 USB ports but only 4 are USB 2 and 4 are USB 1... :mad:
use your mouse/keyboard on the slow ones

Yeah, I've installed a few of those types of boards myself. In fact, I think I still have one like that down in my basement from the old server that I just retired.