Introduction
Video codecs are improving their algorithm time to time which results improvement in video codec. Which you can read here H.263 , H264 and H.265 etc.
So there is also need for improvements in Audio Codecs too. By implementing new tools in audio codecs algorithms the improvement is done. Which makes it more efficient and then it is widely used.
So today in this article we are going to discuss about What Is AAC Audio Codec and how it works? How it is beneficial than traditional MP3 Codec?
What Is AAC Audio Codec ?
AAC stands for Advanced Audio Codec. It is also known as AAC-LC which means Advanced Audio Codec – Low Complexity.
AAC Codec is lossy compression codec for digital audio. Which provides very good audio quality in limited bandwidth, specially when it is compared to MP3.
AAC Codec does supports maximum 48 Channels. It is having good sampling rate of 8 to 96 Khz. So AAC is a audio codec can be called as a successor of MP3 ( MPEG-1 Layer 3) codec.
AAC codec was developed with the help of various contributors like Sony, Nokia, Dolby, AT&T, Bell and Fraunhofer. Later on it was introduced by the MPEG world wide.
How AAC Audio Codec Works ?
As shown above in the figure AAC encoding is a 5 steps process as explained above in the figure.
(1) This is the Domain Conversion step. Where Time domain is converted into Frequency domain signal by the help of MDCT Transformation. MDCT represents the Discrete Cosine Transform.
(2) After the transformation this frequency domain signal is then encoded.
(3) In this step after encoding the error correction is done.
(4) After the error correction it store the signal.
(5) Frame Correction Is Done.
How Does AAC Codec Progression Works ?
There are three step by step tools which implemented in the MPEG-2 AAC-LC for its progression towards MPEG-4 HE-AAC V2.
MPEG-2 AAC -LC is widely used audio compression. The PNS is implemented in it which results MPEG-4 AAC-LC. Where PNS stands for Perceptual Noise Substitution.
Now SBR Technology is implemented in it which results MPEG-4 HE-AAC. SBR represents Spectral Band Implication. Where SBR technique is used in storing and encoding the high frequency information.
Thus MPEG-4 HE-AAC is efficient version of AAC-LC . So is called as MPEG-4 High Efficiency-Advanced Audio Coding.
For better compression and higher audio quality PS tool is implemented. Where PS represents the Parametric Stereo. So it is used to compress the audio more than 30 percent. Which results MPEG-4 HE-AAC Version 2.
PS also controls the left channel and right channel audio. It also reduces the bandwidth consumption.
How AAC Audio Codec Is Better Than MP3 Codec ?
(1) AAC audio codec is good in performance for audio frequency of more than 16 khz.
(2) AAC provides good audio quality in same bitrate than MP3.
(3) AAC supports 48 channel while MP3 supports maximum 5.1 channels.
(4) AAC uses good range of sampling rate that is from 8 to 96 khz while MP3 uses 16 to 48 Khz.
(5) AAC is more convient for Software developers while MP3 is not.
(6) AAC is good for transient and stationary signal.
Thus AAC codec is having more advantages over the MP3 codec. So AAC is more efficient and easy to use with great functionality.
Conclusion
AAC is the good quality audio codec which gives better compression technique to save the bandwidth. Because it remove the signal components which are not required. Also it eliminate the audio signal which are repeating.
MPEG-4 HE-AAC is used in streaming media, Podcasting and radio broadcasting where audio quality is the major concerned. Because it deliver better quality in limited bitrate. It does the audio compression near about 40 percent.
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