Spectral Band Replication (SBR) is a novel audio spectrum recovery technology, it can greatly improve the efficiency of perceptual audio coding compression, and thus more suitable for streaming media applications with limited bandwidth. It will be widely used in the world of digital broadcasting, the third generation mobile communications, multimedia downloads, video-on-demand and other services.
SBR use parametric coding technique that involves complex algorithms; simply take a long time by the hardware circuit design. And this design cannot keep up with the constant development of audio standards. In other words: When a new standard integration into the decoder, it takes a long time to ...view middle of the document...
In order to solve this problem, SBR is used to merge with MP3 and AAC and improve the quality of high frequency information. This shows the fact that SBR has a very good backward compatibility.
With the improvement of HE-AAC and MP3pro, this new technology has been used in many applications. Such as XM satellite radio, MPEG, Digital Radio Mondale and MP3pro. In conclusion, the SBR can enhance the coding efficiency of existing coder for about 30%. It successfully improved the quality high frequency signal without cost more bits, thus provide much better listening experience. In view of all these benefits, I believe the applications of SBR will be using a lot more frequently in the future.
Table of Contents
Executive summary 2
1. Introduction 4
2. Why to use SBR 4
3. Basic Working principle of SBR 5
3.1 SBR Encoder 5
3.2 SBR Decoder 6
4. “Newborn” of old technology 8
4.1 MP3 8
4.2 AAC 8
4.3 Major difference between MP3 and AAC 9
4.4 HE-AAC and MP3pro 9
5. Applications of SBR 10
5.1 XM Satellite Radio 10
5.2 Digital Radio Mondiale (DRM) 10
5.3 3GPP 10
6. Conclusion 10
7. Reference 11
Today, with the growth of technology, people began to pursue higher multimedia quality. For the audio compression, it is now urgent needs for a low bit rate and high quality compression method. Over the past few decades, there are many very successful audio compression methods were invented, among them there are the famous AAC and MP3 technology, both these two technologies are performing very well at low bit rates. In that era, the main transmission rout of audio information that some low-bandwidth cables, such as POTS. High-frequency information is generally not easily perceived by the human ear, so some of the high frequency information was artificially omitted. But with the subsequent performance of individual terminal are much more powerful now. In this reason, a new high-frequency compression method can effectively preserve the high band information is demand imminent. Thus, SBR is starting apply to the systems.
Now, many audio compressor are beginning to use SBR to enhance their performance in the high-frequency part, typically examples are HE-AAC and MP3pro, which is an upgraded version of the AAC and MP3. This article will mainly focus on the SBR working principle, how to achieve high quality and low bit rates, and how is SBR been used to improve the performance in the multimedia audio compression field.
2. Why to use SBR
High quality and low bit rate is a constant task for telecommunication engineering. Due to the frequency band limitation of existing infrastructures, most of old coding method will delete the high frequency signal to achieve low bit rate. While the high frequency signal does no longer exist in the data and available to decode, the reproduced output signal will be either perform lower quality or not acceptable for human perceptual...