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kenhall 3 July 2013

I am producing an audiobook for audible.com in my home studio. This is my first one and I am new to this forum, so advance apologies if I am posting in the wrong forum.

Audible has the following instructions on their web site:

Mastering Guidelines

Once the book is fully edited and QC’d, it should be mastered. Mastering is the process of adjusting the sound to make it more even and "listenable"


Mastering:

Your submitted files should measure between -23dB and -18dB RMS, with peaks hovering around -3dB. Your noise floor should fall between -60dB and -50dB.
To make the audiobook levels louder and more-even throughout is vital. Typically, this process is achieved by RMS normalization around -20db, or compression/limiting. Compression should be applied with a fast attack and release, around a ratio of 3:1. A hard limiter may also be used, and audiobooks are EQ’d during this time, to sweeten the sound and make it more pleasing to the ear. Often, muddled low end and mid-range is cut to make the audiobook sound more clear and smooth.

​Questions:

1) Would somebody kindly interpret this for somebody who is new to these concepts
2) I am currently using GarageBand on a MacBook Pro and suspect that I need some beefier software like Logic Pro to meet these requirements
3) Does the mastering process occur after the recording is done and quality checked using software like Audacity, etc.?

Thanks so much.

Ken

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Comments

hueseph Wed, 07/03/2013 - 21:54

RMS= Root Mean Square. It's a complicated formula. It's like an average loudness but not exactly. It's like an average loudness not including the peaks. The peaks are...well...the peaks. Watch your volume meter. for the most part they want the sound to hover around -23 and as high as -18dB. The sound can go lower but no higher than -3dB at it's peaks. These should be clearly marked on the master volume meter. Garageband should be perfectly fine. If you need to you can look for free metering plugins. Try http://www.lsraudio.com/lvlmeter.html , http://www.voxengo.com/product/span/

Span is particularly good. It has both a detailed meter and a spectral analyzer.

Both of the above plugins are free.

DaleVO Thu, 07/04/2013 - 13:48

kenhall, post: 406098 wrote:
Your submitted files should measure between -23dB and -18dB RMS, with peaks hovering around -3dB. [Hue explained this]

Your noise floor should fall between -60dB and -50dB. [the noise floor is the level of background noise in a signal, or the level of noise introduced by the system... Plug everything in, set gains, and record the silence in your booth. This will give you an idea of your noise floor.]

To make the audiobook levels louder and more-even throughout is vital. Typically, this process is achieved by RMS normalization around -20db, or compression/limiting. Compression should be applied with a fast attack and release, around a ratio of 3:1. [this Compression 101 text may help: [[url=http://[/URL]="ftp://ftp.dbxpro.co…"]"]ftp://ftp.dbxpro.co…]="ftp://ftp.dbxpro.co…"]"]ftp://ftp.dbxpro.co…]

A hard limiter [a type of compressor] may also be used, and audiobooks are EQ’d during this time, to sweeten the sound and make it more pleasing to the ear. Often, muddled low end ["80Hz roll off/high pass filter {HPF}" can sometimes be built in to the mic, audio interface or both] and mid-range is cut [depends on your sound, hardware, and environment] to make the audiobook sound more clear and smooth.

​Questions:

1) Would somebody kindly interpret this for somebody who is new to these concepts
2) I am currently using GarageBand on a MacBook Pro and suspect that I need some beefier software like Logic Pro to meet these requirements [early on, Audacity worked for my VO needs.]
3) Does the mastering process occur after the recording is done and quality checked using software like Audacity, etc.? [Yes, final step.]

Ken,
I hope this helps.
Dale

DaleVO Fri, 07/05/2013 - 18:03

bouldersound, post: 406144 wrote: ...intended to be the final levels and no further processing will be done by Audible.com.

Agreed Boulder. I found the info that the Ken posted, and see that they want the files delivered in 192Kbps, MP3 format. So by their explanation, "mastering" is up to the VO talent. It is my standard M.O. to do some of those tweaks, as needed, while editing, and I never considered that as "mastering", just editing the mix.

bouldersound Fri, 07/05/2013 - 19:35

From that link:

Audiobook.com wrote: Ensure all MP3 files are recorded, edited, and mastered per the Guidelines above (e.g. MP3 mono encoded @ 192 kbps, maximum file size 170MBs [or less than 2 hours], etc.) Mono files are preferred but stereo files are also accepted. All files must contain the same number of channels, i.e. they must be all mono or all stereo. All files must be 44.1kHz.

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