Spoken Podcast encoder

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chetstone
Posts: 8
Joined: Sun May 17, 2009 2:10 am
Location: Crestone, CO, USA

Spoken Podcast encoder

Post by chetstone »

In iTunes Preferences, in the "Import Settings" dialog, Apple offers a "Spoken Podcast" AAC encoder. Does Amadeus Pro provide a similar encoder?

In the Details of this dialog box, the encoder is described as

"32kbps (mono)/64kbps (stereo), 22.5 khz, using voice filtering, optimized for MMX/SSE2"

Will I get this encoder if I select 64 kbps AAC in Amadeus? If I convert my stereo original to mono, will I get 32kbps? (64 kbps is the lowest available setting in Amadeus.)

Most of my recordings are done on my Edirol R-09, so the sample rate is 44.1Khz. Will I need to make some other selection to downsample? Does it matter?

What about the "voice filtering"? Not sure how necessary it is to have that, but I assume I would also have to do some explicit filtering in Amadeus to get it if I wanted?

I think it would be nice if Amadeus Pro simply offered a "Spoken Podcast" encoder that takes care of all this.

Thanks

Chet

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Martin Hairer
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Spoken Podcast encoder

Post by Martin Hairer »

Hi Chet,

right now, Amadeus Pro will only go down to 64kbps, even if the sound
is mono. However, the version at <http://www.hairersoft.com/Downloads/AmadeusPro.zip
should allow you to go down to 32kbps if you convert the sound to
mono first. The encoder should be exactly the same as the one Apple
uses in iTunes.

However, I have no idea what the "voice filtering" is. I suppose that
it is some home-grown filter that they apply to it beforehand in order
to enhance the performance of the encoder in the frequency band
commonly used by human voice. There doesn't seem to be any
documentation about what they use there precisely. It might simply
correspond to applying one of their Audio Units with some particular
setting, but the only way of finding out what this is exactly would
probably be to talk to the Apple engineer who added that function ;-)
Regards,

Martin

HairerSoft
http://www.hairersoft.com/



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chetstone
Posts: 8
Joined: Sun May 17, 2009 2:10 am
Location: Crestone, CO, USA

Post by chetstone »

Thank you Martin!

chetstone
Posts: 8
Joined: Sun May 17, 2009 2:10 am
Location: Crestone, CO, USA

Re: Spoken Podcast encoder

Post by chetstone »

Martin, I finally got a chance to try this out, and it doesn't seem to work.
I can select lower bit rates, e.g. 32 in the AAC settings dialog, but when
I look at the saved file, it is the same size as the 64kbps file, and in the
Finder info it says "Total bit rate: 63".

Also, I wonder if it would be possible to ask for this setting in the batch processor? Not sure how that would work, since the batch processor is
starting with a stereo file and one of the batch operations will be "convert to mono".

Thanks,
Chet
Martin Hairer wrote:Hi Chet,

right now, Amadeus Pro will only go down to 64kbps, even if the sound
is mono. However, the version at <http://www.hairersoft.com/Downloads/AmadeusPro.zip
should allow you to go down to 32kbps if you convert the sound to
mono first. The encoder should be exactly the same as the one Apple
uses in iTunes.

However, I have no idea what the "voice filtering" is. I suppose that
it is some home-grown filter that they apply to it beforehand in order
to enhance the performance of the encoder in the frequency band
commonly used by human voice. There doesn't seem to be any
documentation about what they use there precisely. It might simply
correspond to applying one of their Audio Units with some particular
setting, but the only way of finding out what this is exactly would
probably be to talk to the Apple engineer who added that function ;-)
Regards,

Martin

HairerSoft
http://www.hairersoft.com/



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