Very strange capturing problem, HELP!

[Commander XJL]

When I capture with virtual dub or VideoStudio, I get some popping sounds in the audio, no matter what my settings. If I use a different program to capture I still get it. I am using an ATI 7500 card. If I bypass the card for sound and hook the sound directly into my Soundblaster card I still get the crackling and popping sounds ( I was sure this would fix it!) Now, here is the weird part. If I capture just the audio into Soundforge through my Soundblaster card the sound is perfect!! Now, I don't want to have to capture the video and sound seperate because then I have to put the audio and video back in sync when I author the DVD in Maestro. Why is it I can capture the sound perfect in Soundforge but not Virtual Dub or Ulead VideoStudio? What are these programs doing where the sound is getting recorded with little popping sounds?

[dar1us]

some details please, short computer spec, source of capture.

have you played with different audio rates 44.1kHZ or 48... that kinda thing? what codec are you using to capture audio, try using PCM 48kHZ (or 44.1 kHZ if you are capturing from a video recoder or something like that).

is there constant crackling or only when titles apear, like subtitles or close captions or even credits.

one last thing, play around with the sync settings in the capture program iuVCR, check things like use system clock for both audio/video because the crackling could be from that. Also, can you capture all frames accuratly at what ever region you are in, 25fps in PAL, 29.97 fps in scabby NTSC *no offense:)*


dar1us

[theReal]

What are these programs doing where the sound is getting recorded with little popping sounds?I'm not sure if this has anything to do with it, but I also get crackling/popping sounds in the audio on Realvideo playback. I found out that this is only on my computer, so it must be the video playback that causes the noises and I think it has something to do with harddrive activity during playback (Via Southbridge...you never know...).

Maybe there could be a similar problem with your recordings? I mean, during capture of a video, the harddrive activity is much higher than during capture of audio only. You say you have an SB sound card, do you have a VIA chipset? That could explain some sound problems...

[dar1us]

@real, u replied to 2 of my posts at once, wow, I feel... honoured:)

But... yeh, good idea, if you have a VIA chipset, why not grab the latest VIA's, Hyperion 445's. (www.viaarena.com) - WHATEVER HAPPENED TO VIAHARDWARE:(

[Swan]

If I capture just the audio into Soundforge through my Soundblaster card the sound is perfect!!
So, the noise and crackling is generated even when you bypass the audio part of the capture card? I assume you have hooked it up like this:
You take the audio from the source straight into your Soundblaster audio card.

If that is your setup, have you checked the audio levels on the recordings? Are you leaving enough headroom or does the audio get overmodulated?
It is crucial in digital audio recording to never let the audio peak at 0 DB. I use -6 or -4 DB, that leaves enough headroom to never overmodulate.

Extract the audio from one of the "crackling" videos and study it in Soundforge. At what level are your peaks?

Also, have you checked that no other line-in's etc are actice when you capture? I get humming, for example, when a certain input on my audio card is not muted.

/Swan