Results 1 - 10
of
1,112
MPEG: A video compression standard for multimedia applications,”
- Commun. ACM,
, 1991
"... ..."
(Show Context)
Analysis, Modeling and Generation of Self-Similar VBR Video Traffic
, 1994
"... We present a detailed statistical analysis of a 2-hour long empirical sample of VBR video. The sample was obtained by applying a simple intraframe video compression code to an action movie. The main findings of our analysis are (1) the tail behavior of the marginal bandwidth distribution can be accu ..."
Abstract
-
Cited by 542 (6 self)
- Add to MetaCart
(Show Context)
We present a detailed statistical analysis of a 2-hour long empirical sample of VBR video. The sample was obtained by applying a simple intraframe video compression code to an action movie. The main findings of our analysis are (1) the tail behavior of the marginal bandwidth distribution can be accurately described using "heavy-tailed" distributions (e.g., Pareto); (2) the autocorrelation of the VBR video sequence decays hyperbolically (equivalent to long-range dependence) and can be modeled using self-similar processes. We combine our findings in a new (non-Markovian) source model for VBR video and present an algorithm for generating synthetic traffic. Trace-driven simulations show that statistical multiplexing results in significant bandwidth efficiency even when long-range dependence is present. Simulations of our source model show long-range dependence and heavy-tailed marginals to be important components which are not accounted for in currently used VBR video traffic models. 1 I...
Fast subsequence matching in time-series databases
- PROCEEDINGS OF THE 1994 ACM SIGMOD INTERNATIONAL CONFERENCE ON MANAGEMENT OF DATA
, 1994
"... We present an efficient indexing method to locate 1-dimensional subsequences within a collection of sequences, such that the subsequences match a given (query) pattern within a specified tolerance. The idea is to map each data sequence into a small set of multidimensional rectangles in feature space ..."
Abstract
-
Cited by 525 (24 self)
- Add to MetaCart
(Show Context)
We present an efficient indexing method to locate 1-dimensional subsequences within a collection of sequences, such that the subsequences match a given (query) pattern within a specified tolerance. The idea is to map each data sequence into a small set of multidimensional rectangles in feature space. Then, these rectangles can be readily indexed using traditional spatial access methods, like the R*-tree [9]. In more detail, we use a sliding window over the data sequence and extract its features; the result is a trail in feature space. We propose an ecient and eective algorithm to divide such trails into sub-trails, which are subsequently represented by their Minimum Bounding Rectangles (MBRs). We also examine queries of varying lengths, and we show how to handle each case efficiently. We implemented our method and carried out experiments on synthetic and real data (stock price movements). We compared the method to sequential scanning, which is the only obvious competitor. The results were excellent: our method accelerated the search time from 3 times up to 100 times.
Agile Application-Aware Adaptation for Mobility
- SOSP-16
, 1997
"... In this paper we show that application-aware adaptation, a collaborative partnership between the operating system and applications, offers the most general and effective approach to mobile information access. We describe the design of Odyssey, a prototype implementing this approach, and show how it ..."
Abstract
-
Cited by 504 (32 self)
- Add to MetaCart
(Show Context)
In this paper we show that application-aware adaptation, a collaborative partnership between the operating system and applications, offers the most general and effective approach to mobile information access. We describe the design of Odyssey, a prototype implementing this approach, and show how it supports concurrent execution of diverse mobile applications. We identify agility as a key attribute of adaptive systems, and describe how to quantify and measure it. We present the results of our evaluation of Odyssey, indicating performance improvements up to a factor of 5 on a benchmark of three applications concurrently using remote services over a network with highly variable bandwidth.
The TV-tree -- an index structure for high-dimensional data
- VLDB Journal
, 1994
"... We propose a file structure to index high-dimensionality data, typically, points in some feature space. The idea is to use only a few of the features, utilizing additional features whenever the additional discriminatory power is absolutely necessary. We present in detail the design of our tree struc ..."
Abstract
-
Cited by 215 (7 self)
- Add to MetaCart
(Show Context)
We propose a file structure to index high-dimensionality data, typically, points in some feature space. The idea is to use only a few of the features, utilizing additional features whenever the additional discriminatory power is absolutely necessary. We present in detail the design of our tree structure and the associated algorithms that handle such `varying length' feature vectors. Finally we report simulation results, comparing the proposed structure with the R -tree, which is one of the most successful methods for low-dimensionality spaces. The results illustrate the superiority of our method, with up to 80% savings in disk accesses. Type of Contribution: New Index Structure, for high-dimensionality feature spaces. Algorithms and performance measurements. Keywords: Spatial Index, Similarity Retrieval, Query by Content 1 Introduction Many applications require enhanced indexing, capable of performing similarity searching on several, non-traditional (`exotic') data types. The targ...
An Image Multiresolution Representation for Lossless and Lossy Compression
- IEEE TRANSACTIONS ON IMAGE PROCESSING
, 1996
"... We propose a new image multiresolution transform that is suited for both lossless (reversible) and lossy compression. The new transformation is similar to the subband decomposition, but can be computed with only integer addition and bit-shift operations. During its calculation the number of bits ..."
Abstract
-
Cited by 213 (11 self)
- Add to MetaCart
We propose a new image multiresolution transform that is suited for both lossless (reversible) and lossy compression. The new transformation is similar to the subband decomposition, but can be computed with only integer addition and bit-shift operations. During its calculation the number of bits required to represent the transformed image is kept small through careful scaling and truncations. Numerical results show that the entropy obtained with the new transform is smaller than that obtained with predictive coding of similar complexity. In addition, we propose entropy-coding methods that exploit the multiresolution structure, and can efficiently compress the transformed image for progressive transmission (up to exact recovery). The lossless compression ratios are among the best in the literature, and simultaneously the rate vs. distortion performance is comparable to those of the most efficient lossy compression methods.
The JPEG2000 still image compression standard
- IEEE Signal Proc. Mag
, 2001
"... The development of standards (emerging and established) by the International Organization for Standardization (ISO), the International Telecommunications Union (ITU), and the International Electrotechnical Commission (IEC) for audio, image, and video, for both transmission and storage, has led to wo ..."
Abstract
-
Cited by 178 (11 self)
- Add to MetaCart
(Show Context)
The development of standards (emerging and established) by the International Organization for Standardization (ISO), the International Telecommunications Union (ITU), and the International Electrotechnical Commission (IEC) for audio, image, and video, for both transmission and storage, has led to worldwide activity in developing hardware and software systems and products applicable to a number of diverse disciplines [7], [22], [23], [55], [56], [73]. Although the standards implicitly address the basic encoding operations, there is freedom and flexibility in the actual design and development of devices. This is because only the syntax and semantics of the bit stream for decoding are specified by standards, their main objective being the compatibility and interoperability among the systems (hardware/software) manufactured by different companies. There is, thus, much room for innovation and ingenuity. Since the mid 1980s, members from both the ITU and the ISO have been working together to establish a joint international standard for the compression of grayscale and color still images. This effort has been known as JPEG, the Joint
Defending Against Statistical Steganalysis
- 10th USENIX Security Symposium
, 2001
"... The main purpose of steganography is to hide the occurrence of communication. While most methods in use today are invisible to an observer's senses, mathematical analysis may reveal statistical anomalies in the stego medium. These discrepancies expose the fact that hidden communication is happe ..."
Abstract
-
Cited by 163 (1 self)
- Add to MetaCart
(Show Context)
The main purpose of steganography is to hide the occurrence of communication. While most methods in use today are invisible to an observer's senses, mathematical analysis may reveal statistical anomalies in the stego medium. These discrepancies expose the fact that hidden communication is happening. This paper presents improved methods for information hiding. One method uses probabilistic embedding to minimize modifications to the cover medium. Another method employs error-correcting codes, which allow the embedding process to choose which bits to modify in a way that decreases the likelihood of being detected. In addition, we can hide multiple data sets in the same cover medium to provide plausible deniability.
Towards Robust and Hidden Image Copyright Labeling
, 1995
"... This paper first presents a "hidden label" approach for identifying the ownership and distribution of multimedia information (image or video data) in digital networked environment. Then it discusses criteria and difficulties in implementing the approach. Finally a method using a JPEG model ..."
Abstract
-
Cited by 144 (1 self)
- Add to MetaCart
(Show Context)
This paper first presents a "hidden label" approach for identifying the ownership and distribution of multimedia information (image or video data) in digital networked environment. Then it discusses criteria and difficulties in implementing the approach. Finally a method using a JPEG model based, frequency hopped, randomly sequenced pulse position modulated code (RSPPMC) is described. This method supports robustness of embedded labels against several damaging possibilities such as lossy data compression, low pass filtering and/or color space conversion. 1 Introduction The electronic representation and transfer of digitized multimedia information (text, video, and audio) have increased the potential for misuse and theft of such information, and significantly increases the problems associated with enforcing copyrights on multimedia information [1,2]. These problems are rooted from the intrinsic features of the digitally formated information: (1) making copies is easy and inexpensive; (...
