M. Bosi et al., "ISO/IEC MPEG-2 Advanced Audio Coding" 101 AES Convention, Los Angeles, CA, Nov. 1996  Home/Search   Document Not in Database   Summary   Related Articles   Check

....can be viewed as time reversed versions of the synthesis transition filters. The analysis switch from 1024 to 128 bands is obtained by time reversing Fig. 13 and the switch from 128 to 1024 bands by time reversing Fig. 12. The next example is for the MPEG 2 Advanced Audio Coding audio coder [12]. It has a filter bank with 2 modes and uses the switching algorithm described in [5] Both modes have orthogonal filters with a standard system delay, one has 1024 bands and a filter length of 2048 taps (i.e. delay 2047) the other has 128 bands and a length of 256 taps (delay 255) The mode with ....

M. Bosi et al., "ISO/IEC MPEG-2 Advanced Audio Coding" 101 AES Convention, Los Angeles, CA, Nov. 1996

....programming will be supported in the future. So, it is important to investigate techniques for supporting such streaming services. In particular, we shall examine in this paper how link adaptation and power control can improve the error performance for delivering MPEG 4 Advanced Audio Coder (AAC) [2] coded music in the Enhanced General Packet Radio Services (EGPRS) network [3] In one extreme, voice service in the EGPRS network has a very stringent delay requirement, which precludes the possibility of retransmission in case of packet error. In addition, voice also requires a very low packet ....

....re assembly at the mobile terminal is necessary. 2. 2 Parameters of MPEG 4 Advanced Audio Coder The basic idea behind perceptual audio coders such as MPEG 4 Advanced Audio Coder (AAC) is to hide quantization noise below the signal dependent masking thresholds of the human auditory system [2, 13]. With AAC, the audio stream is divided into subbands using a filter bank, which uses a 1024 point Modified Discrete Cosine Transform (MDCT) Quantization noise (step size) is set separately in each subband to fall below the masking threshold. In addition, correlation between audio samples is used ....

M. Bosi, et al., "ISO/IEC MPEG-2 Advanced Audio Coding", J. Audio Eng. Soc., vol. 45, No. 10, October 1997, pp. 789-812.

....edges in images) it is best to have a few short filters. In [20] it was shown how to design a time varying cosine modulated TDAC filter bank [5] However, its filters are orthogonal with length restricted to and a system delay of samples. That algorithm is used, e.g. in ISO MPEG audio coders [21]. Later approaches were mainly for nonmodulated filter banks [22] 28] and for the orthogonal case [29] To address the above issues, this paper treats the following main points: It describes how to design filter banks with a truly arbitrary delay, which can be specified in single sample steps, ....

....modulated filters by limiting the overlap between filters of different modes to one block. Switching the analysis from 1024 to 128 bands and from 128 to 1024 bands is obtained by time reversing Figs. 9 and 10, respectively. The next example is for the MPEG 2 advanced audio coding audio coder [21], which is a proposed standard, targeted at delivering CD quality sound at a bit rate of 64 kb s mono. It has a filter bank with two modes and uses the switching algorithm described in [20] Both modes have orthogonal filters with a standard system delay: One has 1024 bands and a filter length of ....

M. Bosi et al., "ISO/IEC MPEG-2 advanced audio coding," in Proc. 101 AES Conv., Los Angeles, CA, Nov. 1996.

....the perceptual coding of a natural audio soundtrack. By always thinking of sound applications in terms of the parametric spaces they use, it becomes possible to interrelate and compare techniques from disciplines that are normally disparate. For example, an audio coding format such as MPEG 2 AAC [10] can be considered as the combination of 1) a sound understanding algorithm that sets parameters in representation space by analyzing an acoustic waveform; 2) transmission of these parameters; 3) a sound synthesis algorithm that maps from the transmitted parameters to a new sound. In audio ....

....technique has been recently standardized for use in the DVD audio format [16] Modern audio coders achieve better performance than lossless compressors by allowing errors; that is, by using lossy coding and exploiting two other important aspects. First, perceptual coders such as MPEG 2 AAC [10] have a model of perceptual irrelevancy. Irrelevancy is the notion that there are aspects of sounds that cannot be perceived by the human listener and therefore do not need to be transmitted. It is also possible to think of irrelevancy as a kind of perceptual equivalence; that 918 IEEE ....

M. Bosi, K. Brandenburg, S. Quackenbush, L. Fielder, K. Akagiri, H. Fuchs, M. Dietz, J. Herre, G. Davidson, and Y. Oikawa, "ISO/IEC MPEG-2 advanced audio coding," J. Audio Eng. Soc., vol. 45, no. 10, pp. 789--814, 1997.

....(GA) coder allows the transmission of highquality broadband multichannel signals such as music at bitrates from 16 to 64 kb s channel. This coder is a state of theart, scalable version of well known perceptual compression techniques [9] it is based on the MPEG 2 Advanced Audio Coding standard [10] with additional improvements in quality and functionality for MPEG 4. The CELP coder uses codebook excitation linear prediction techniques [11] 12] to enable highly compressed speech coding between 16 and 24 kb s. The parametric speech coder is based on the harmonic vector excitation coding ....

M. Bosi, K. Brandenburg, S. Quackenbush, L. Fielder, K. Akagiri, H. Fuchs, M. Dietz, J. Herre, G. Davidson, and Y. Oikawa, "ISO/IEC MPEG-2 advanced audio coding," J. Audio Eng. Soc., vol. 45, no. 10, pp. 789--814, 1997.

....not just in the channel. Protection mechanisms include tamper resistant software and hardware. These techniques are discussed in [2] and [12] 2.1 Compression As discussed earlier, compression enables the distribution of music or video over networks. For audio, the MPEG 2 Advanced Audio Coder [1] provides CD quality reproduction for most music and most listeners at a compression ratio of 11 to 1 (128 kilobits per second) Compression may also be relevant as a protection mechanism for the following two reasons. Attackers will always have access to decompressed output. If recompression of ....

M. Bosi, K. Brandenburg, S. Quackenbush, L. Fielder, K. Akagiri, H. Fuchs, M. Dietz, J. Herre, G. Davidson, Y. Oikawa, "ISO/IEC MPEG-2 Advanced Audio Coding", presented at the 101 st Convention of the Audio Engineering Society, Nov. 1996, preprint 4382.

....being via 28.8 kbps or slower modems) it s also hard to store. However, improvements in network and storage technologies will soon lower these barriers. Perhaps the most fundamental advance is in compression technology. For audio, perceptual algorithms such as the new MPEG 2 Advanced Audio Coder [AAC] give near CD quality for most music and most listeners at a compression rate of 11 to 1 (128 kilobits per second) We can store more music in less space, storage is becoming cheaper and networks will allow greater throughput. All music currently distributed on CDs is unprotected. When public ....

....should not be used to gate access to content. Bitstream (semantic non altering) Watermarking: Bitstream marking algorithms manipulate the compressed digital bitstream without changing the semantics of the audio or video stream. For example, a data envelope in an MPEG 2 Advanced Audio Coding (AAC [AAC]) audio frame could contain a watermark, albeit one which could easily be removed, e.g. by the parser mentioned above. Bitstream marking is lowcomplexity so can be used to carry transaction information. Because the mark signal is unrelated to the media signal, the bit rate these techniques can ....

M. Bosi, K. Brandenburg, S. Quackenbush, L. Fielder, K. Akagiri, H. Fuchs, M. Dietz, J. Herre, G. Davidson, Y. Oikawa, "ISO/IEC MPEG-2 Advanced Audio Coding", presented at the 101 st Convention of the Audio Engineering Society, Nov. 1996, preprint 4382.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC