View Single Post
  #3  
Old 2008-09-24, 03:06 PM
direwolf-pgh's Avatar
direwolf-pgh direwolf-pgh is offline
On the Beach
 
Join Date: Dec 2005
Location: down in the basement
Re: suggestion/question

more audio info per type
Quote:
Dolby Digital, or AC-3, is the common version containing up to six discrete channels of sound. The most elaborate mode in common usage involves five channels for normal-range speakers (20 Hz – 20,000 Hz) (right front, center, left front, right rear and left rear) and one channel (20 Hz – 120 Hz) for the subwoofer driven low-frequency effects. Mono and stereo modes are also supported. AC-3 supports audio sample-rates up to 48kHz.
Quote:
MPEG-1 Layer II is defined in ISO/IEC 11172-3

Sampling rates: 32, 44.1 and 48 kHz
Bitrates: 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 and 384 kbit/s
An extension has been provided in MPEG-2 Layer II and is defined in ISO/IEC 13818-3

Additional sampling rates: 16, 22.05 and 24 kHz
Additional bitrates: 8, 16, 24, 40 and 144 kbit/s
The format is based on successive digital frames of 1152 sampling intervals with four possible formats:
Quote:
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 many bit rates.

AAC has been standardized by ISO and IEC, as part of the MPEG-2 & MPEG-4 specifications. The MPEG-2 standard contains several audio coding methods, including the MP3 coding scheme. AAC is able to include 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 15 low frequency enhancement (LFE, limited to 120 Hz) channels and up to 15 data streams. AAC is able to achieve indistinguishable audio quality at data rates of 320 kbit/s (64kbit/s/channel) for five channels. The quality is close to CD also at 96 kbit/s (48kbit/s/channel) for stereo.

AAC's best known use is as the default audio format of Apple's iPhone, iPod, iTunes, and the format used for all iTunes Store audio (with extensions for proprietary digital rights management).

Last edited by direwolf-pgh; 2008-09-24 at 03:15 PM.
Reply With Quote Reply with Nested Quotes