Relationship between RMS and peak level

[larryjc]

Sorry - newbie here and trying to get my tracks to meet ACX requirements - used the plugin and it works fine but I fail to meet the ACX requirements as my RMS value is wrong. Can't find how to change it!! help would be gratefully received.

[larryjc]

HI - been reading avidly here and learnt a great deal as I've decided to narrate and produce my own books - I had a publisher for my first one but did the narration - he got the files to ACX standard but I pay for the privilege. I've downloaded the ACX analyser and it works fine. I've worked out how to get lovely silence between phrases and pass the -60db check but can't work out how to get the rms between 18 and 23db and keep the peaks below -3db.
I've tried changing the microphone level and can get the rms fine but then if I say a word even slightly too loud I exceed the peak even if its only occasionally. I can adjust the amplification or normalisation to keep a peak of -3 but then the rms goes out or I can get the rms in but the peak goes out as there seems to be a fixed relationship between them. Is there any way to get both within limits???
In anticipation.

[Gale Andrews]

Please don't post the same question in different topics. I merged the topics for you.

[larryjc]

Sorry am I being really stupid? - I can do what the other poster asked and adjust the volume - what I can't do is then get the peak value back down.

[larryjc]

Ah sorry - m y post got crossed because one took longer to moderate than the other and I thought it had disappeared.

[steve]

The usual problem is that when the peak level is -3 dB (ACX requirement), the RMS level is a bit too low. Is that your problem?
If so, how much too low is it?

[larryjc]

With the one of my basic tracks I have a peak of -4.3 and a rms of -30 if I normalise the peak to -3 the rms goes to 28.8. Some of the others aren't quite so extreme but the same applies if I normalise the peak I still have an rms above 23. Why can't I disconnect the two?

[kozikowski]

That's pretty common. Are you using "acx-check?" Is that the software you said you had at the top of the thread? There is a technique to manually read all three ACX specifications on your work, but it's pretty painful and time consuming. ACX Check gives you the whole pile in one swipe.

http://wiki.audacityteam.org/wiki/Nyqui ... #ACX_Check

My experience has been to slide a pass of compressor in your processing path. Compressor's job is to boost low volume without affecting high volume.

Audio Compressor
-- Select the whole clip or show by clicking just above MUTE.
-- Effect > Normalize: [X]Remove DC, [X]Normalize to -3.2 > OK
-- Effect > Compressor: Thresh -20, Floor -40, Ratio 2:1, Attack 0.2, Release 1.0, > OK
-- Effect > Normalize: [X]Remove DC, [X]Normalize to -3.2 > OK

That will give you the -3 for show peaks, it will give you a higher RMS (Loudness) and it will affect noise. It's always a juggling act between the two loudness values and noise. If your RMS is not loud enough, run that whole process again on the original show and increase the Ratio from 2:1 to 2.5:1 or even 3:1. Everything else stays the same.

Normalize is set to 3.2 instead of 3 to guard against the MP3 process pushing you over by accident. The specification is just not go over 3.0 in the deliverable.

See how you do.

Koz

[kozikowski]

If you're feeling adventurous, record a test sound clip according to this recipe ...

http://www.kozco.com/tech/audacity/Test ... _Clip.html

... and post it here. We'll see if your processing list matches ours. Do Not Process It. Raw recording only.

Koz

[larryjc]

Koz - you're a star - and saved me tons of work re-recording - that worked fine. I am using the ACX check diagnosis package and can now get on with recording. Many thanks. (mind you I haven't a clue why it works but who cares!)

larry