We estimated the world’s technological capacity to store, communicate, and compute information, tracking 60 analog and digital technologies during the period from 1986 to 2007. In 2007, humankind was able to store 2.9 × 10 20 optimally compressed bytes, communicate almost 2 × 10 21 bytes, and carry out 6.4 × 10 18 instructions per second on general-purpose computers. General-purpose computing capacity grew at an annual rate of 58%. The world’s capacity for bidirectional telecommunication grew at 28% per year, closely followed by the increase in globally stored information (23%). Humankind’s capacity for unidirectional information diffusion through broadcasting channels has experienced comparatively modest annual growth (6%). Telecommunication has been dominated by digital technologies since 1990 (99.9% in digital format in 2007), and the majority of our technological memory has been in digital format since the early 2000s (94% digital in 2007).

/pdf/the-world-s-technological-capacity-to-store-communicate-and-39dybc0mey.pdf

The World’s Technological Capacity to Store, Communicate, and Compute Information

Overview of the MPEG-4 Standard and Error Resilience Investigations

Parametric-stereo coding is a technique to efficiently code a stereo audio signal as a monaural signal plus a small amount of parametric overhead to describe the stereo image. The stereo properties are analyzed, encoded, and reinstated in a decoder according to spatial psychoacoustical principles. The monaural signal can be encoded using any (conventional) audio coder. Experiments show that the parameterized description of spatial properties enables a highly efficient, high-quality stereo audio representation.

/pdf/parametric-coding-of-stereo-audio-4fznz7nwhj.pdf

Parametric coding of stereo audio

In 2004 the ISO/MPEG Audio standardization group started a new work item on efficient and backward-compatible coding of high-quality multichannel sound using parametric coding techniques. Finalized in the fall of 2006, the resulting MPEG Surround specification allows the transmission of surround sound at bit rates that have been commonly used for coding of mono or stereo sound. The results of the standardization process are summarized by describing the underlying ideas and providing an overview of the MPEG Surround technology. The performance of the scheme is characterized by the results of recent verification tests. These tests include several operation modes as they would be used in typical application scenarios to introduce multichannel audio into existing audio services.

/pdf/mpeg-surround-the-iso-mpeg-standard-for-efficient-and-3rognjg23n.pdf

MPEG Surround – the ISO/MPEG Standard for Efficient and Compatible Multi-Channel Audio Coding

Preface. 1. Introduction. 2. Signal Processing Essentials. 3. Quantization and Entropy Coding. 4. Linear Prediction in Narrowband and Wideband Coding. 5. Psychoacoustic Principles. 6. Time-Frequency Analysis: Filter Banks and Transforms. 7. Transform Coders. 8. Subband Coders. 9. Sinusoidal Coders. 10. Audio Coding Standards and Algorithms. 11. Lossless Audio Coding and Digital Watermarking. 12. Quality Measures for Perceptual Audio Coding. References. Index.

http://jdsp.engineering.asu.edu/books/cover-page-audio+contents.pdf

Audio Signal Processing and Coding

MPEG Spectral Band Replication (SBR) is the newest compression technology available as part of the MPEG standards. It is combined with MPEG Advanced Audio Coding (AAC) and improves coding efficiency by more than 30%. The resulting scheme is called High-Efficiency AAC (HE AAC). This presentation explains MPEG SBR and its integration into the existing MPEG-4 bitstream format. The SBR technology itself as well as the implications on systems based on MPEG-4 technology are described. Signaling through MPEG-4 Systems and other transport formats is introduced and typical applications and usage scenarios are listed.

A Closer Look into MPEG-4 High Efficiency AAC

A method for error concealment in an encoded audio signal, whereby a set of spectral coefficients are divided into at least two sub-bands(14), whereupon said sub-bands undergo reverse transformation (16). A specific prediction is performed (18) for each quasi- time signal of a sub-band in order to obtain an estimated temporal representation for a sub-band of a set of spectral coefficients following on from a real set. Forward transformation (20) of the time signal of each sub-band provides estimated spectral coefficients that can be used (28) instead of defective spectral coefficients of a subsequent set of spectral coefficients in order to conceal transmission errors, for example. Sub-band transformation provides independence from transformation characteristics such as frame length, window type or MDCT algorithm, while at the same time ensuring that spectral processing is maintained for error concealment, whereby the spectral characteristics of audio signals can also be taken into account during said error concealment.

Method and device for error concealment in an encoded audio-signal and method and device for decoding an encoded audio signal

The present invention relates to techniques for authentication of data streams. Specifically, the invention relates to the insertion of identifiers into a data stream, such as a Dolby Pulse, AAC or HE AAC bitstream, and the authentication and verification of the data stream based on such identifiers. A method and system for encoding a data stream comprising a plurality of data frames is described. The method comprises the step of generating a cryptographic value of a number N of successive data frames and configuration information, wherein the configuration information comprises information for rendering the data stream. The method then inserts the cryptographic value into the data stream subsequent to the N successive data frames.

Authentication of data streams

An entropy encoder includes an apparatus for producing a data stream which comprises two reference points, of code words of variable lengths, the apparatus comprising a first device for writing at least a part of a code word into the data stream in a first direction of writing, starting from a first reference point, and a second device for writing at least a part of a code word into the data stream in a second direction of writing, which is opposite to the first direction of writing, starting from the other reference point. In particular, when a raster having a plurality of segments is used to write the code words of variable lengths into the data stream, the number of the code words which can be written starting at raster points is doubled, in the best case, such that the data stream of code words of variable lengths is robust toward a propagation of sequence errors.

Apparatus and method for producing a data stream and apparatus and method for reading a data stream

A device for concealing an error in an erroneous or potentially erroneous information unit generates output values of a forward decoder and a backward decoder which differ and thus indicate an error-concealment area. The different values for one and the same information unit are examined with regard to a predetermined criterion so as to select that value which meets the predetermined criterion, i.e. which is plausible. Thus, an elimination or reduction of the continuation errors introduced in the decoding of blocks of reversible code words of variable lengths is achieved without impacting the compression rate.

Device and method for concealing an error

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