Digital Audio for Ansomniacs....

Colin Campbell

I am so bored tonight that I decided to start a tech discussion for the uninitiated about what exactly digital audio is. I'm sure this will be a short lived thread but here goes.

Digital audio is "sampled" so many times a second. Usually 44.1 thousand times a second. So every 44.1 thousand times a second, a snapshot of the audio at that instant is taken. For each of these "samples" you usually have 16 bits to describe it. Those 16 bits can be one of two things... zero or one. If you know anything about number systems you realize that this is a binary or "base two" number system, Instead of the usual base ten (or decimal) number system we use every day. You can only have a 0 or 1 and not 2,3,4,5 etc. So... what happens if in that 44.1 thousanth of a second, all 16 bits are 1's? You have nothing left. This is what is known as "all ones" and you have lost the ability to describe the volume level at that precise instant as being any higher. If you exceed this maximum describable instant in sound you "clip." Digital clipping is quite possibly the worst sound known to man. A sort of "ripping" that has has the same effect on the human ear as fingernails on a chalkboard. This being said, you want to get as close as you can to all ones without hitting it so that processing and down sampling into mp3's and such has as much to work with as possible with as little noise as possible.

I am sure that there is someone to debate the details... so let'er rip.

Keith D. Milby · Posted: Sun Feb 25, 2007, 15:49 (GMT) Post subject:

Great Stuff Colin. Thanks for it. People go to talking about 1's and 0's and I will usually pull up a chair.

I was messing around with some of the raw audio I have recorded. Now I use Audacity, because I am really trying to give open source a chance and the last thing I spend money on is software. I have been using these raw audio files to learn how to use Audacity and become familiar with audio software in general.

So of course they have breaths, ticks, pops and burbs of all sorts. I have been experimenting with different techniques on getting rid of them, selecting and turning down the amplitude works much better than just silencing it all together.

Does "The Great Colini" have any words of wisdom he would like to share on this topic. If not, could you do a magic trick.

Heather Cooper · Posted: Sun Feb 25, 2007, 17:13 (GMT) Post subject:

Thanks! I am basically trying to absorbed everything I can at this point.

J.S. Gilbert · Posted: Tue Feb 27, 2007, 02:43 (GMT) Post subject:

If 1010011101001101 does 011100010010010 and 0111001001011101 then 111001000010100 should 0111100101001000.

But that's just my opinion

Colin Campbell · Posted: Tue Feb 27, 2007, 17:12 (GMT) Post subject:

Keith... I totally silence only when it it going over music or something. But, I'm talking breaths. As far as clicks and burps, I don't think they should be there in the first place.

Sometimes when they are trying to cram to much copy in to a short space, I just edit out the breaths. Gives it more 'hype" and gets their god awful read in to the time alloted. Sounds unatural in a straight read though.

Keith D. Milby · Posted: Tue Feb 27, 2007, 17:47 (GMT) Post subject:

Total silence does work fine when the voice is over a music bed. The other stuff (click, pops, burps) was an attempt at jocularity. Poorly executed though it would seem.

Here is another question for The Great Colinni. What is your order of execution on EQ, Normalizing, Compression and alike. What do you do to ready a file for production. I myself, compress, normalize and then go through and clean up the undesirable noise, breaths and spaces.

Standing by anxiously awaiting your reply. If any one else would like to chime in, I would also be interested in hearing from you as well.

Colin Campbell · Posted: Tue Feb 27, 2007, 19:19 (GMT) Post subject:

I normalize first but usually not much normalizing goes on because I am very concious of the levels going it and try to be as close as possible to 100 percent to begin with (without going over of course.) It seems the meters in Audition try to protect you from yourself because digital "0" aint really digital 0. If it were and you hit it, disaster would strike.

Now as for the rest, it depends on the project. I guess generally I would compress next then EQ if I needed any but the only EQ I would need would be for an effect not to just generally make me sound good. I do THAT outboard on my Symetrix before it ever hits the digital world.

J.S. Gilbert · Posted: Tue Feb 27, 2007, 23:42 (GMT) Post subject: source for good info

Keith,

Obviously when it comes to getting work over the internet we have to look at both the technology and the craft.

Here is a site that has teremendous info

http://www.tweakheadz.com/compressors.htm

I do caution however that less is often more and rarely does a sesion get screwed up becuase someone recorded it raw. Many of my engineeer friends with Emmys and Oscars and that sort of thng all swear by recording with the dials at "12 O'clock".

The biggest problem most P.C. users have is recording with other programs running in the background. Even some of the more benign start programs can interject lots of clips and pops and other nonsense into your recording. Aledgedly, VISTA (probably the $500 version) will eliminate some ofthese issues. I'm waiting about 3 or 6 months to get VISTA though, so in the meantime I use a trimmed down computer that is dedicated to just audio video for my recordings. when I am done recording, I transfer my recordings via a USB thumb drive to my "everything" computer and sned them to the respective parties that way. The other problem PC users get is conflicting IRQ's and whacky drivers. Every now and again my computer doesn't recognize something and I boot and reboot. Not even the ubergeeks I know can easily explain it.

Joseph Sinclair · **Voice Seeker** Joined: 20 Jan 2008 Posts: 17

I'm using VISTA and haven't had trouble with oddball sounds. I'm glad to hear it's good for something. It sure is slow.

My guess is that defragmenting one's hard drive before each recording session will eliminate many noise problems.

Thomas C. Gass · Posted: Tue Feb 05, 2008, 09:32 (GMT) Post subject:

There are 10 different ways to understand Digital Audio:

Either you do (1) or you don't (0)

Wink

(just to please Mr. Gilbert) Dancing

Thomas