- published: 23 Oct 2012
- views: 122840
Advanced Audio Coding (AAC) is a standardized, lossy compression and encoding scheme for digital audio. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates.
AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4 specifications. Part of the AAC known as High-Efficiency Advanced Audio Coding (HE-AAC) which is part of MPEG-4 Audio is also adopted into digital radio standards like DAB+ and Digital Radio Mondiale, as well as mobile television standards DVB-H and ATSC-M/H.
AAC supports inclusion of 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 16 low frequency effects (LFE, limited to 120 Hz) channels, up to 16 "coupling" or dialog channels, and up to 16 data streams. The quality for stereo is satisfactory to modest requirements at 96 kbit/s in joint stereo mode; however, hi-fi transparency demands data rates of at least 128 kbit/s (VBR). The MPEG-2 audio tests showed that AAC meets the requirements referred to as "transparent" for the ITU at 128 kbit/s for stereo, and 320 kbit/s for 5.1 audio.
When I think of it now that it's done
How it might've gone without a place to belong
I can see we played into their hands
And they picked our bones until we proved them wrong
It's only a moment
The minutes and hours, they fly from me now as then
It's all in the detail
I've been here before but still don't remember when
As we stared in the face of the storm
And the change began to gather over the bend
There was always a chance it would come
But if you can't make it happen nobody can
It's all but forgotten
The minutes and hours, they're nothing that can't be
bought
It's all in the detail