Low Complexity Profile (LC) - the simplest and most widely used and supported.The standard offers four default profiles: Depending on the complexity of the bitstream to be encoded, the desired performance and the acceptable output, implementers may create profiles to define which of a specific set of tools they want use for a particular application. What this all means to the listener is better and more stable quality than MP3 at equivalent or slightly lower bitrates.ĪAC takes a modular approach to encoding. More flexible joint stereo (separate for every scale band).Much better handling of frequencies above 16 kHz.Higher coding efficiency for transient signals (blocksize: 192 -> 128 samples).Higher coding efficiency for stationary signals (blocksize: 576 -> 1024 samples).Sample frequencies from 8 kHz to 96 kHz (official MP3: 16 kHz to 48 kHz). Although the AAC codec specified in MPEG-2 Part 7 and the AAC specified in MPEG-4 Part 3 are somewhat different, they are both informally known as AAC (for clarity it is best to refer specifically either to MPEG-2 AAC or to MPEG-4 AAC). The codec design was further improved in MPEG-4 Part 3, known formally as ISO/ IEC 14496-3, with the addition of Perceptual Noise Substitution (PNS) and a Long Term Predictor (LTP). AAC, which was first specified in the standard known formally as ISO/ IEC 13818-7, was published in 1997 as a new "part" (distinct from ISO/ IEC 13818-3) in the MPEG-2 family of international standards. AAC was designed as an improved-performance codec relative to MP3 (which was specified in MPEG-1) and MPEG-2 Part 3 (which is also known as "MPEG-2 Audio" or ISO/ IEC 13818-3). Advanced Audio Coding ( AAC) is a lossy data compression scheme intended for audio streams.
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