Re: Problem with AAC and AudioFile
Re: Problem with AAC and AudioFile
- Subject: Re: Problem with AAC and AudioFile
- From: William Stewart <email@hidden>
- Date: Wed, 21 Jan 2004 16:16:06 -0800
There are properties in the AudioConverter that allow you to set all
these. Mainly:
bit rate
output sample rate (this can be set in the sample rate field of the AAC
stream description when you create the converter as well)
encoding quality
Bill
On 21/01/2004, at 3:33 PM, john wrote:
Hi Bill,
Thanks for the additional info, I look forward to the new sample code.
If I've missed something, I apologise, but is there any way to set
details about the encoding quality or related variables? If not, what
is the standard compression rate?
-- John
AAC was first specified in MPEG-2.
MPEG-4 adding some additional tools to the basic codec (what is
called "Low Complexity AAC") such as PNS (Perceptual Noise Shaping),
and redefined a predictive tool defined in MPEG2 that was
computationally very complex (great english!) (and was specified in
the Main Profile version of AAC), to use LTP (Long Term Prediction)
instead (which is less computationally complex, but achieves a
similar result in the encoding quality)
set all fields to zero
set the type field to 'aac '
Sorry, its a little complex to explain the complete process... We're
trying to get the SDK out (but I keep thinking of one more thing to
add) that will provide extensive code to show you how to make, read,
play any file type known by the AudioFile API using that,
AudioConverter and the AU output units.
Bill
--
mailto:email@hidden
tel: +1 408 974 4056
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