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| seavixen |
 Posted: Sep 29 2002, 02:53 PM |
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Unregistered
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Hello
I have noticed that clicks and pops appear in audio files recorded by VirtualDub in my PC. These are spottable only during real music play, and not during silences.
I am capturing using VDub, Pinnacle PCTV Studio, and a SBlaster Live! card.
The audio level is set such as peaks are at -4 dB.
To check that this is not a Soundblaster problem, I tried to capture audio through an audio program such as Cool Edit and there are no clicks and pops with Cool Edit.
So I think it is VDub who generates the clicks and pops.
I have tried some of the timing/sync settings but I still get the clicks and pops, who are noticeable if you record a stereo broadcast of classical music.
Has anybody experienced this, and possibly is there a solution or workaround?
Thanks a lot for your help.
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| phaeron |
| Posted: Sep 29 2002, 09:44 PM |
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Virtualdub Developer
Group: Administrator
Posts: 7773
Member No.: 61
Joined: 30-July 02
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SoundBlaster Live! cards have rather strict DMA timing requirements that are not met on some systems when video capture is active, due to the much higher bus load. The Creative drivers also reportedly change a PCI bus parameter, PCI latency timer, that lowers the total throughput of the bus -- this has been reported to sometimes produce video corruption as well. Try capturing at 160x120 or a similar low resolution and see if it reduces the frequency of the clicks; also, if you are running Athlon+VIA, check that you have the latest 4-in-1's.
The Pinnacle PCI Performance Enhancer:
http://www.pinnaclesys.com/support/display...3&ProductID=307
may also help.
I think the Microsoft drivers don't drop the PCI latency timer like the Creative ones do, but you lose functionality and speed using those.
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| seavixen |
| Posted: Sep 30 2002, 10:54 AM |
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Thanks Phaeron
I have indeed a VIA chipset motherboard although the processor is an old K6-2 at 500Mhz. The Via Drivers are up-to-date and I have Pinnacle PCI enhancer installed.
I tried to reduce the workload as you suggested.
First I Lowered the PC screen resolution, and changed from Huffman compression to a plain capture with no compression.
The clicks and POPs indeeded have reduced their frequencies. Surprisingly when I tried capturing at 160 xwhatever the CPU workload did not drop and neither the clicks and pops.
I will try to do other things to lower the CPU workload.
Do you think a more modern PC, with say a 1.7 GHz Athlon will solve the problem?
Thanks again.
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| seavixen |
| Posted: Oct 2 2002, 09:15 AM |
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Unregistered
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The Microsoft drivers for the SoundBlaster Live! do not sort the problem out.
Instead, changing the Pinnacle card driver apparently is a cure.
I've replaced the Pinnacle driver with a GNU generic for Conexant/BT chipset.
The pops have disappeared, at least so far.
Another advatage is that this driver allows more control over the card (e.g. white balance).
A small disadvantage is that the Overlay mode that with the Pinnacle Driver used to show a perfect video, is now actually showing the video at the captured resolution.
Another disadvantage is that Vdub cannot maintain memory of the actual size of the captured frame in pixels for each mode chosen, although during capture one can see that the numbers are correct.
I mean if you set a mode such as YUsomething it will show that you need 104K or so bytes per frame, will capture at that rate, but will show more than 380K (false) if you open again the dialog box. This maybe a small bug in VDub or in the GNU driver. |
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