Paul,
Not sure this is what you are referring to, but iTunes music store downloads have an extension of .m4p These files are "protected AAC" file, i.e. encrypted Advanced Audio Coding format files. Unencrypted AAC files have an extension of .m4a
A google search on AAC yielded the following info:
First: http://www.apple.com/mpeg4/aac/ has a lot of background information and a PDF file MPEG-4 Fact Sheet.
Second: the following excerpt comes from: http://www.vialicensing.com/products/mpeg4aac/standard.html
Advanced Audio Coding (AAC) is a wideband audio coding algorithm that exploits two primary coding strategies to dramatically reduce the amount of data needed to convey high-quality digital audio. First, signal components that are "perceptually irrelevant" and can be discarded without a perceived loss of audio quality are removed. Next, redundancies in the coded audio signal are eliminated. Efficient audio compression is achieved by a variety of perceptual audio coding and data compression tools, which are combined in the MPEG-4 AAC specification.
The MPEG-4 AAC standard incorporates MPEG-2 AAC, forming the basis of the MPEG-4 audio compression technology for data rates above 32 kbps per channel. Additional tools increase the effectiveness of AAC at lower bit rates, and add scalability or error resilience characteristics. These additional tools extend AAC into its MPEG-4 incarnation (ISO/IEC 14496-3, Subpart 4).
HTH.
Marian
On Dec 27, 2004, at 7:53 PM, Paul Salyers wrote:
I heard there was a better sound format called MP4. Anyone know any thing about this for sure?
Paul Salyers PS1 - Senior Rep. [EMAIL PROTECTED] http://ps1.softseven.org _______________________________________________ use-revolution mailing list [email protected] http://lists.runrev.com/mailman/listinfo/use-revolution
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