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AAC for voice/audiobooks... worth the time?, Getting a new iPod soon...
br0adband
post Jun 3 2003, 07:31
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So I'm curious to know if AAC supports decent bitrates/filesizes for voice and audiobooks uses. I figured if I buy a 30GB iPod and use something like that mp4 uploader I can load up quite a bit of voice tracks/audiobooks. I'm a Windows user (no flames please) although I wouldn't expect that to make much difference.

Any information provided is greatly appreciated.

br0adband


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rjamorim
post Jun 3 2003, 07:45
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AAC should do well on voice samples. But the best quality judge is you. Download Psytel AACenc from rarewares and try it with your voice samples. Start with a high bitrate, and start reducing it until you reach a sweet spot. Add some overhead for difficult samples, and you'll get your optimal AAC-for-voice bitrate.


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menno
post Jun 3 2003, 08:00
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The new iPod also supports the MPEG-4 CELP codec (according to the "legal" section of the thing itself, I never tried it).

I think the MPEG-4 CELP reference code already outputs very acceptable speech quality. Taking the highest bitrate of this codec is probably better than taking AAC for pure voice.

Menno
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br0adband
post Jun 3 2003, 08:19
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Cool... nice to know.

Thanks


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blessingx
post Jun 3 2003, 13:21
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iPod also support the Audible format (basically mp3 protected). Check out their site. Where I get most of my audio books.
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M
post Mar 19 2004, 11:19
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QUOTE (menno @ Jun 3 2003, 02:00 AM)
The new iPod also supports the MPEG-4 CELP codec (according to the "legal" section of the thing itself, I never tried it).

I think the MPEG-4 CELP reference code already outputs very acceptable speech quality. Taking the highest bitrate of this codec is probably better than taking AAC for pure voice.

Menno

Pardon my ignorance, but the only CELP codec I'm aware of (as a free download) is Speex. Does that mean the new iPod supports the *.spx format, if renamed to something the iPod would recognize? Or is there another freely downloadable MPEG-4 CELP codec that I've overlooked, which would allow users to encode their own audiobooks? (And if it is included in FAAC, I somehow missed it....)

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menno
post Mar 19 2004, 12:16
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QUOTE (M @ Mar 19 2004, 11:19 AM)
Pardon my ignorance, but the only CELP codec I'm aware of (as a free download) is Speex. Does that mean the new iPod supports the *.spx format, if renamed to something the iPod would recognize? Or is there another freely downloadable MPEG-4 CELP codec that I've overlooked, which would allow users to encode their  own audiobooks? (And if it is included in FAAC, I somehow missed it....)

Oh, there are dozens of different CELP codecs. I thought QuickTime Pro used to have an option to encode to MPEG-4 CELP but in my version the option is disabled (maybe I need some extra plugin).

iPod definately doesn't support speex. The legal section of my iPod says: ACELP.NET (http://www.voiceage.com/) for Audible (http://www.audible.com/) speech files (so probably not MPEG-4 CELP). The ACELP.NET codec is available but I'm not sure how to produce files compatible with the iPod.

Menno
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