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Amorya · Oct 21, 2003, 07:39 PM

I'm about to make some audio books, and I'm wondering what format to have them in. I was thinking 128kbps MP3, but someone said that the files would be huge if we did it that way.

So what are the iTunes ones in? And what would be the easiest way to get maximum quality and lowest file size?

Amorya

wataru · Oct 21, 2003, 07:49 PM

I think they're in their own special format.

dreilly1 · Oct 21, 2003, 07:59 PM

We've made some audio books from CD before. Two things to consider:

1) The bit rate is per track. Do you really need an audiobook in stereo? Ripping in Mono effectively cuts the file size in half.

2) Sopken word will sound better at a lower bit rate than music, since there's usually more dynamic range in a song than there is in a person's voice. 64 kbps may be pushing it, but 80 or 96 should be fine.

I have Harry Potter III in my iTunes library right now: at 96kbps mono, the entire book (nearly 12 hours) fits in less than 500 mb. That may seem like its big, but it is 12 hours that can fit in a CD (with room to spare)!

car1son · Oct 21, 2003, 10:11 PM

iTunes audiobooks are supposed to be from Audible.com. For audio books, I'm an Audible customer rather than an iTunes customer. The format is Audible's own (it plays in the iPod.) The suffix is .aa.

Audible offers several quality levels on a scale of 1-5 (from "telephone quality" to "MP3 quality" to use their terms). This determines file size and thus download time. I usually get their "3" ("FM Radio quality"), which iTunes tells me is 16KBPs and uses 7MB of disk space per hour. It sounds fine to me for spoken word (a little clipped on the high end but perfectly suitable to speech.)

Note you can rip to MP3 (or AAC) but specifiy a slower bit rate than the default 128KPBS. iTunes Preferences / Importing - pick "Custom" under bit rate. Try a few and see how they sound to you.

Gee4orce · Oct 22, 2003, 02:54 AM

It's worth noting that the .aa files support bookmarking too. You can pause an audiobook, go and listent to a few music tracks or whatever, and when you return to the audio book it picks up from where it left off.

Kind of handy !

Amorya · Oct 22, 2003, 06:09 AM

Originally posted by Gee4orce:
It's worth noting that the .aa files support bookmarking too. You can pause an audiobook, go and listent to a few music tracks or whatever, and when you return to the audio book it picks up from where it left off.

Kind of handy !

I assume there's no way to make files in that format myself?

The audiobook we're making is fairly questionable legally - it's a piece of fan-fiction. So we couldn't sell it or anything. So I doubt asking Audible for help would get us very far

Amorya

Eug · Oct 22, 2003, 08:54 AM

I would suggest trying a test at 56 Kbps mono AAC and seeing how that works out.

Or else something like 64 Kbps mono MP3 at a reduced sample rate (eg. 16 KHz).

You can tweak the settings up or down from there.

dreilly1 · Oct 22, 2003, 08:59 AM

Originally posted by Amorya:
I assume there's no way to make files in that format myself?

The audiobook we're making is fairly questionable legally - it's a piece of fan-fiction. So we couldn't sell it or anything. So I doubt asking Audible for help would get us very far

Amorya

Ahh... Well, in that case, what you want to do is record the book as audio, and then encode it to MP3, no? (I've done that before, too, with audio tapes, let me know if you need help there) Audible's "format" is just AAC with a DRM wrapper around it anyway, just like the m4p files. (in fact, I wouldn't be suprised if audible.com was the first "live test" for the iTunes DRM scheme.) Straight MP3 would be so much better for what you're doing.

You could use unprotected AAC from iTunes to make your book, and get equivalent quality at a lower bit rate and file size, but there's less support for AAC right now outside of the iTunes universe.

I'm familiar with Audible, and I had no idea that the "FM quality" tracks were only 16kbps (although I do believe they use AAC, so that's probably more like 24kbps MP3.) It sounds like you can get very passable sound at bit rates below 96 kbps, then. Maybe you should record a few minutes of the book, then rip the resulting audio into a range of bit rates, and figure out what sounds best for you.

If you have a friend with a Linux box, I'd try LAME for the encoding, though. I've found the LAME encoder to be superior to iTunes' encoder. Although I've never tried it at low bit rates, it makes a difference at higher ones. Maybe it will help you exract a little more quality out of 24 or 32kbps MP3's. LAME does have a OS X port, but I've never tried it...

Amorya · Oct 22, 2003, 11:21 AM

Originally posted by dreilly1:
Ahh... Well, in that case, what you want to do is record the book as audio, and then encode it to MP3, no? (I've done that before, too, with audio tapes, let me know if you need help there)

I should be OK. My main problem is finding some audio editing software for cheap. I'm having different people read out different lines (one for each character), and I need some software to edit it all together.

Logic would be ideal, but...well, I'm a student. With little cash. The free version of ProTools would be great if it ran on OSX. I even have a copy of MicroLogic, but again it's OS9 only.

Amorya

King Bob On The Cob · Oct 22, 2003, 12:21 PM

I read somewhere that it is 24 kb/sec AAC...

yellowdog · Oct 22, 2003, 12:25 PM

Just out of curiosity, what does say a 300 page book translate into mb storage space? I realize that there is a difference in words/page and all that, but just looking for a ball park figure.

chabig · Oct 22, 2003, 12:59 PM

I bought a book on CDs and encoded it using iTunes to a mono MP3 at 16kHz using 16kbps. I tried a variety of rates but this encoding seemed to be the best bang for the buck. Of course, higher bitrates and bandwidths sound better, but at the cost of much larger files. The 7 hour 16 minute book took 50MB at these settings. And the quality is perfect for my car, which is where I listen most.

Chris

yellowdog · Oct 22, 2003, 01:34 PM

Originally posted by chabig:
The 7 hour 16 minute book took 50MB at these settings.
Chris

That seems reasonable for storage space. Maybe it is time to finally listen to War and Peace.

wataru · Oct 22, 2003, 02:43 PM

Originally posted by yellowdog:
Just out of curiosity, what does say a 300 page book translate into mb storage space? I realize that there is a difference in words/page and all that, but just looking for a ball park figure.

Well, it all depends on what quality you want, and how long it takes to read those 300 pages.

bitrate * time = filesize

Many people have quoted various options for bitrates, so all you need to do is pick one, and figure out how long it takes to read 300 pages.

dreilly1 · Oct 22, 2003, 03:37 PM

Originally posted by Amorya:
I should be OK. My main problem is finding some audio editing software for cheap. I'm having different people read out different lines (one for each character), and I need some software to edit it all together.

Audacity is a freeware audio editor.

http://audacity.sourceforge.net/

I've only ever used it for Linux, but supposedly they have a OS X port.

Jim_MDP · Oct 22, 2003, 03:39 PM

Oh, for the love of Ed...

Trek Porn as Audiobook.

It's the end times I tells ya.

Amorya · Oct 22, 2003, 03:39 PM

Originally posted by dreilly1:
Audacity is a freeware audio editor.

http://audacity.sourceforge.net/

I've only ever used it for Linux, but supposedly they have a OS X port.

I was more after a sequencer... something to cut and splice a load of different files together.

If the worst comes to the worst I guess I could use SoundStudio or something, but I imagine it'd take ages.

Amorya

chabig · Oct 22, 2003, 03:59 PM

I think Audacity would be perfect for you. You can cut and arrange tracks, then mix it all down.

Chris

Amorya · Oct 22, 2003, 04:00 PM

Originally posted by Jim_MDP:
Oh, for the love of Ed...

Trek Porn as Audiobook.

It's the end times I tells ya.

Harry Potter, actually. Here's a sample

Harry broke the kiss, but only to move his mouth down her neck, to duck under her chin and run his tongue down her throat, to hear that moaning sound again she�d made in the Charms classroom. Her hand went to the belt of his dressing gown, he felt her hands on his chest, then her lips, tracing a moist trail down to his stomach, making his abdominal muscles flinch. He gasped at the sensation, then brought her face up to his again, holding her tightly, desperately. His fingers deftly undid the buttons down the front of her nightshirt, her hand went to the drawstring on his pajama pants. Harry felt he was drowning in her, and didn�t want to be saved, couldn�t imagine anything more wonderful in the world than to sink down into this whirlpool called Hermione...

Sorry! I didn't write the book - I'm just in charge of making an audiobook out of it.

Amorya

wataru · Oct 22, 2003, 04:41 PM

Originally posted by Amorya:
Sorry! I didn't write the book - I'm just in charge of making an audiobook out of it.

I'm so sorry.

dreilly1 · Oct 22, 2003, 09:32 PM

ewww.

car1son · Oct 22, 2003, 09:53 PM

Originally posted by Amorya:
My main problem is finding some audio editing software for cheap.

If cheap is important, iMovie edits the sound track along with the video, and imports Quicktime.