Corrupted sound when capturing but not when recording!

[SupaCoopa]

Hello people.
My previous post has mysteriously disappeared, so I re-post along with some additions.

When I capture audio & video with any program (Virtual Dub, AVI_IO, Adobe Premiere) the sound is strangely corrupted. When someone talks or when music is playing I can hear something like a cracking sound . When there is silence nothing is heard, as normal. Listening more careful to the "corrupted" recordings through hi-fi speakers, it seems that the sound is actually vibrating, both in tone and volume. This is really strange as while listening to real-time line-in the sound is clear; distortion is only produced on the captured file. If I record line-in from a non-video-capture program like WinRec, Cool Edit etc the recording is perfect!

I'm capturing at various resolutions using various codecs with no lost frames. I have tried every available sound format, from 11khz-4 bit-mono to 48khz-16 bit-stereo and the results are identical.
Only line-in is selected as recording input, and everything else is muted at playback properties.

Computer is Celeron 900, VIA chipset, 512K Ram, NVidia MX 400 VIVO, SB Live Value and run Windows XP Pro with latest drivers available; I have modified the NVIDIA WDM drivers to enable PAL capture.
Software is VDub 1.4.5 and 1.4.8, AVI_IO 3.11, Premiere 6 Trial.

Any ideas what is actually happening and how can it be fixed?
Cheers

[lady7]

I have a very similiar sound issue. If anyone can find the cause for the vibration noise during capture i would like to know too. i have also gone into volume control and done all that. Also wireless items can interfere and cause noise issues. my dv bridge is causing the problem but it's intermittant. oh well, this is life

[THE RIPPER]

i have encountered the same problem before.what sound card do you have?

[Dragonsf]

When you look at the captured .wav with CooleEdit in spectral view, you will notice a red short peak at the beginning of each frame. With normal sound (volume more than 30dB), you won't recognize this distortion, but with quiet sound, it can be heard. You can remove these peaks with CoolEdit. With PAL these peaks occur every 25th of a second (30/sec on NTSC). As the peaks are really jumps in the sample value, you can hear them with good equipment but only at low volume passages.
I have no solution to this, as it seems that these errors are generated by the HW. (Maybe a recording through a line-in device could solve it, but you'll get sync probs and it would take twice the time to capture - it's not wise do do anything besides capturing video at capturing time)

[spiderman2k1]

I had the same problem when I captured the sound was fine when I burn two VCD sound pop all over. I changed my ram I had 64SDram and to 32meg stick that did not like each other went to best buy bought two sticks of PC100 PNY and keep the 64meg stick fixed the problem

[SupaCoopa]

I actually cured the problem yesterday.
I had a look at BIOS settings and found out that AGP WS Read and AGP WS Write were disabled. I set them both to enabled and distortions have disappeared ever since! Why graphics card BIOS settings affect sound recording is beyond me, but I now get crystal clear sound when capturing. Well, as good as analog connections can provide anyway...

Before that I had a glance at the official Creative Sound Blaster forum. It seems that a huge number of SB users get distortions on their recordings. These problems occur with all models ranging from SB 128 to latest Audigies and under all Windows versions. I considered myself lucky reading those posts, as I only had problems when capturing, not just recording. Now that I managed to fix it I'm feeling even luckier!

A piece of advice I can now give: Fiddle with every hardware option imaginable including switching PCI slots, altering irrelevant BIOS settings etc and cross your fingers every time you restart your PC!

Hope this is of some help to troubled people