Subject:View wave pattern on the fly while recording

Posted by: Rose

Date:1/26/2004 10:42:03 AM

Hi,

I have everything set up and working well, thanks for the help. However, I find that setting levels is a hit or miss deal. The windows faders are hyper sensitive. The slightest change on the slider can have a huge effect on the recorded sound levels. The bar graphs in the record window are helpful but far from a dead accurate indication of what's being recorded. What we/I need is some sort of monitor to view the wave pattern as it's coming through. Is this possible, either in SF or using a third party program? Right now I just use trial and error, and multiple test runs before committing to a take - a masterpiece of inefficiency. There has to be a better way.

Thanks if you have any tips.

Subject:RE: View wave pattern on the fly while recording

Reply by: Geoff_Wood

Date:1/27/2004 1:09:31 AM

You don't need to view the input waveform at all. The record level meters in the SF record dialogue are exact.

What sliders are these that are hypersensitive - you soundcard's mixer applet ? That's the only place you can change input levels on your PC.

geoff

Subject:RE: View wave pattern on the fly while recording

Reply by: Chienworks

Date:1/27/2004 9:48:43 AM

It's a lot easier if you set the meters to hold peaks (right-mouse-button click on the meters and you'll see some options). If i get peaks anywhere in the -0.1dB to -15dB range i'm usually pretty satisfied. It's easy enough to normalize after recording.

Subject:RE: View wave pattern on the fly while recording

Reply by: CKAudio

Date:1/28/2004 12:19:34 PM

To avoid the hyper-sensitive recording level adjustment, I purchased an inexpensive mixing board and use it to control the recording levels. One such mixer is the Soundcraft COMPACT 4 (www.spiritbysoundcraft.com), but there are many on the market. Behringer, Mackey, and Samson all make them.

Just route your input signals to the mixing board and route the mixing board's outputs to the input of the sound card.

You'll never regret it.

Subject:RE: View wave pattern on the fly while recording

Reply by: Rose

Date:1/31/2004 12:10:21 PM

Mixing boards are great. I was hoping for a software solution, but if there isn't one, then I have nothing against mixing boards. Used them many a time.

Thanks.




Oh, and note. I found that if you tab around the recording property window and highlight the line in fader, you can use the arrow keys for more precise movement. Trying to use the mouse was a joke. This isn't the perfect solution but it'll do until I can get better. Thanks again, both.

Subject:RE: View wave pattern on the fly while recording

Reply by: Rose

Date:1/31/2004 12:18:57 PM

Oops, didn't see this one sneak in here. Can you give a few more words on the hold peaks idea? I searched help but came up dry. ... tho I did see the wave hammer stuff (which I don't have).

Secondly, I'm dealing with some pretty bad recordings to begin with. How much will normalizing distort the sound if I use it as a booster?

Thanks again.

Subject:RE: View wave pattern on the fly while recording

Reply by: Chienworks

Date:1/31/2004 1:35:18 PM

Peak Hold is a function of the meter display. Right-mouse-button click directly on the meters and you'll get a little popup window. Some of the options that it lets you set are the scale of the meters, hold peaks, and hold valleys. When you have the hold peaks selected a bright line will remain on the meters at the loudest level for a few moments. This means that you can see what the peak level was for a while even it the peak only lasted an instant. It's probably a lot easier to see than to explain. ;) The same thing works for hold valleys; a dark line remains on the meter display at the quietest level for a few moments.

Normalize has almost no effect on sound quality. All it does is increase the volume so that the loudest peak approaches 0dB. The only thing to watch out for is that if you rely on it for extreme cases you may end up with extra noise. This isn't because the normalize function adds noise though. It's because if you record too quietly then the noise level of the sound card will be a substantial portion of what you record and bringing the volume up raises this noise level as well as the signal. This is why it's good to record lounder than softer, but you don't want to risk going above 0dB so leaving yourself some space below 0dB is a good idea.

Subject:RE: View wave pattern on the fly while recording

Reply by: Rose

Date:1/31/2004 8:14:22 PM

> a bright line will remain on the meters at the loudest level

Ah, okay. There is also a digital number at the top of each meter that marks the loudest point. I've been using that as a guide as well.

> Normalize... bringing the volume up raises this noise level as well as the signal.

Right. Signal to noise, not distortion, is just the thing I was thinking. Now, this raises a couple related questions.

What are the optimal recording levels? either with a view to raw recording or with a view to normalizing afterward. We're talking peak levels, of course. SF has those gray lines at 6db. How far above or below that limit would be considered acceptable... or should those lines be ignored and we aim for ideal limits regardless of arbitrary markings?

Secondly, and this is perhaps more interesting, has anybody made a site demonstrating noise removal? You know, with before and after samples, and a description of how the sound was processed to make the difference? I'm dealing with every conceivable type interference imaginable and something like that would be an invaluable resource.

Subject:RE: View wave pattern on the fly while recording

Reply by: Chienworks

Date:1/31/2004 8:48:55 PM

The problem with that number at the top is that it stays there until you reset it. If you bring the volume down this is reflected by the peak hold line, but not by the numbers without a manual intervention.

The optimum recording level is to have the loudest peaks hit just below 0dB. But, it's difficult to know what recording level will produce this result in advance. Since you lose information when the sound clips at 0dB it's safer to use a lower level to make sure the clips don't occur. As long as the recorded signal is loud enough to maintain a usable signal to noise ratio then it's loud enough. Here's a simplified example: the sound card in the recording computer i use at church has a S/N ratio of about 78dB and the pulpit mic has a S/N ratio of about 73dB. However, the air circulation system produces a noise level that is only about 45dB lower than our pastor's speaking voice at the microphone. This means that if i record the sermon with the peaks hitting -28dB then i'm not introducing any significant additional noise by recording at such a low level. After i normalize the mic's noise level is raised 28dB to -45dB, but this is the same level as the ventilation system's noise anyway, so it really doesn't make a difference. (OK, true, it's actually a lot more complex than that, but this shows the basic idea.) So, why knock myself out trying to set a level to make the loudest peaks near 0dB and risk distortion when i can coast at a safer lower level and normalize after?

The -6dB lines are there to show you where -6dB is, that's all. They aren't a guide for proper levels. Why -6dB? Because that's almost exactly 1/2 of the maximum 0dB level, i guess.

I've been asked to make up a noise reduction tutorial site and it's still kinda sitting there on the back burner. I may get around to it some day. Check out the help screens that come with it; they explain a lot.

Subject:RE: View wave pattern on the fly while recording

Reply by: kbruff

Date:2/3/2004 5:50:05 PM

This may sound silly, but for the sake of being a public Geek I will give it a shot. I have a PCI oscilloscope card in my DAW. On occassion I route a copy of the incoming audio signal to the channel A input on my scope card. WIth this additional tool I can indeed view the waveform while SF7 records the waveform for me. The signal conditioning aspects are cooperative since the load impedance on the card is so low that signal is hardly affected while it is being recorded.

check out...

http://www.wuntronic.de/gage/8500e.htm

This one is a great baby, and it talks with all your favorite Analysis programs.

Comments welcomed,
Kevin
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