Search results for "sign"

Hits ?▲	Authors	Title	Venue	Year	Link	Author keywords
13	Valentin Puente, Ramón Beivide, José A. Gregorio, J. M. Prellezo, José Duato, Cruz Izu	Adaptive Bubble Router: A Design to Improve Performance in Torus Networks.	ICPP	1999	DBLP DOI BibTeX RDF	Interconnection subsystem, hardware routers, VLSI de-sign, simulation, performance evaluation, parallel computers
13	Romesh M. Jessani, Michael Putrino	Comparison of Single- and Dual-Pass Multiply-Add Fused Floating-Point Units.	IEEE Trans. Computers	1998	DBLP DOI BibTeX RDF	multiply-add fused, multiply array, alignment shifter, sign encoding, Floating-point unit, Booth encoding
13	David M. Saxe, Richard A. Foulds, Arthur W. Joyce III	Dual Level Intraframe Coding for Increased Video Telecommunication Bandwidth.	International ACM Conference on Assistive Technologies	1998	DBLP DOI BibTeX RDF	gesture, sign language, hearing impairments, disability access
13	S. Augustine Su, Richard Furuta	VRML-based Representations of ASL Fingerspelling on the World Wide Web.	International ACM Conference on Assistive Technologies	1998	DBLP DOI BibTeX RDF	World Wide Web, World Wide Web (WWW), Virtual Reality Modeling Language, VRML, hand gestures, American Sign Language
13	Kirsti Grobel, Hermann Hienz	Fuzzy video-based handshape recognition.	SAC	1996	DBLP DOI BibTeX RDF	handshape structure model, image processing, sign language, fuzzy classification
13	György Turán, Farrokh Vatan	On the Computation of Boolean Functions by Analog Circuits of Bounded Fan-in (Extended Abstract)	FOCS	1994	DBLP DOI BibTeX RDF	explicit nonlinear lower bounds, computation of Boolean functions, bounded fan-in, real-valued functions, sign-representation, n-variable function, piecewise linear circuits, complexity, upper bounds, nondeterminism, analog circuits
13	Saugata Basu, Richard Pollack, Marie-Françoise Roy	On the Combinatorial and Algebraic Complexity of Quantifier Elimination	FOCS	1994	DBLP DOI BibTeX RDF	complex geometry, first order formulae, asymptotically fastest algorithm, input polynomials, sign partition, polynomials, quantifier elimination, combinatorial complexity, algebraic complexity, real closed fields, first order theory, complexity bound
13	Jean Duprat, Jean-Michel Muller	The CORDIC Algorithm: New Results for Fast VLSI Implementation.	IEEE Trans. Computers	1993	DBLP DOI BibTeX RDF	sign functions, fast VLSI implementation, signed-digit implementation, carry-save representation, branching CORDIC method, constant normalization factor, online delay, cosine functions, VLSI, signal processing, digital arithmetic, CORDIC algorithm
13	Behrooz Parhami	On the Implementation of Arithmetic Support Functions for Generalized Signed-Digit Number Systems.	IEEE Trans. Computers	1993	DBLP DOI BibTeX RDF	zero detection, arithmetic support functions, generalized signed-digit number systems, OSD number representation, borrow-free subtraction, overflow handling, digital arithmetic, redundant number representations, carry-free addition, sign detection
13	Stamatis Vassiliadis, Eric M. Schwarz, Baik Moon Sung	Hard-Wired Multipliers with Encoded Partial Products.	IEEE Trans. Computers	1991	DBLP DOI BibTeX RDF	hardwired multipliers, encoded partial products, multibit overlapped scanning multiplication algorithm, sign-magnitude, encoding, digital arithmetic, multiplying circuits, two's complement
13	Dharma P. Agrawal	High-Speed Arithmetic Arrays.	IEEE Trans. Computers	1979	DBLP DOI BibTeX RDF	carry-look-ahead, carry-save, pipelining, multiplication, division, Arrays, square-root, square, high-speed arithmetic, sign detection, multifunction
12	Utsav Drolia, Zhenyan Wang, Srinivas Vemuri, Madhur Behl, Rahul Mangharam	Demo abstract: AutoPlug - An automotive test-bed for ECU testing, validation and verification.	IPSN	2011	DBLP BibTeX RDF
12	Md. Mahbubur Rahman, Amin Ahsan Ali, Andrew Raij, Mustafa al'Absi, Emre Ertin, Santosh Kumar 0001	Demo abstract: Online detection of speaking from respiratory measurements collected in the natural environment.	IPSN	2011	DBLP BibTeX RDF
12	Claro Noda, Shashi Prabh, Carlo Alberto Boano, Thiemo Voigt, Mário Alves	Poster abstract: A channel quality metric for interference-aware wireless sensor networks.	IPSN	2011	DBLP BibTeX RDF
12	Matthias Keller, Jan Beutel	Demo abstract: Efficient data retrieval for interactive browsing of large sensor network data sets.	IPSN	2011	DBLP BibTeX RDF
12	Johannes Schneider 0002, Roger Wattenhofer	Poster abstract: Message position modulation for power saving and increased bandwidth in sensor networks.	IPSN	2011	DBLP BibTeX RDF
12	Charalambos Sergiou, Marios Koutroullos, Vasos Vassiliou	Poster abstract: A congestion mitigation approach using mobile nodes in Wireless Sensor Networks.	IPSN	2011	DBLP BibTeX RDF
12	Mudasser Iqbal, Daiqin Yang, Talha Obaid, Teng Jie Ng, Hock-Beng Lim	Demo abstract: A service-oriented application programming interface for sensor network virtualization.	IPSN	2011	DBLP BibTeX RDF
12	Vinaitheerthan Sundaram, Patrick Eugster, Xiangyu Zhang 0001	Demo abstract: Diagnostic tracing of wireless sensor networks with TinyTracer.	IPSN	2011	DBLP BibTeX RDF
12	Anthony Schoofs, Alex Sintoni, Gregory M. P. O'Hare, Antonio G. Ruzzelli	Demo Abstract: Appliance Load Monitoring by Power Load Disaggregation.	SECON	2010	DBLP DOI BibTeX RDF
12	Hector Ouilhet	Google Sky Map: using your phone as an interface.	Mobile HCI	2010	DBLP DOI BibTeX RDF
12	Christoph Burnikel, Stefan Funke, Kurt Mehlhorn, Stefan Schirra, Susanne Schmitt	A Separation Bound for Real Algebraic Expressions.	Algorithmica	2009	DBLP DOI BibTeX RDF	Separation bound, Zero testing, Exact geometric computation
12	Pieter Verhaeghe, Jorn Lapon, Bart De Decker, Vincent Naessens, Kristof Verslype	Security and Privacy Improvements for the Belgian eID Technology.	SEC	2009	DBLP DOI BibTeX RDF
12	Byungmun Lee, Yeonhee Park	Bridge transmission method of medical sensor node in u-healthcare services.	ICHIT	2009	DBLP DOI BibTeX RDF	medical sensor, u-health, sensor network, Zigbee, home care
12	Michael Stini, Martin Mauve	Enabling fair offline trading.	IWCMC	2009	DBLP DOI BibTeX RDF	digital ownership, fair exchange of signatures, offline trading, simultaneous contract signing
12	Stefan Schirra	Much Ado about Zero.	Efficient Algorithms	2009	DBLP DOI BibTeX RDF	zero separation bound, exact geometric computation paradigm, real algebraic number computation
12	Joakim Eriksson, Fredrik Österlind, Thiemo Voigt, Niclas Finne, Shahid Raza, Nicolas Tsiftes, Adam Dunkels	Accurate Power Profiling of Sensornets with the COOJA/MSPSim Simulator.	MASS	2009	DBLP DOI BibTeX RDF
12	Loh Zhi Chang, Steven Zhiying Zhou	Robust pre-processing techniques for OCR applications on mobile devices.	Mobility Conference	2009	DBLP DOI BibTeX RDF	Otsu threshold, mobile device, OCR, Optical Character Recognition, pre-processing
12	Jörg Müller 0001, Juliane Exeler, Markus Buzeck, Antonio Krüger	ReflectiveSigns: Digital Signs That Adapt to Audience Attention.	Pervasive	2009	DBLP DOI BibTeX RDF
12	Jill Freyne, Michal Jacovi, Ido Guy, Werner Geyer	Increasing engagement through early recommender intervention.	RecSys	2009	DBLP DOI BibTeX RDF	community, social networking, recommender systems, web 2.0, adoption, social software, participation
12	Praveen Gauravaram, Lars R. Knudsen	On Randomizing Hash Functions to Strengthen the Security of Digital Signatures.	EUROCRYPT	2009	DBLP DOI BibTeX RDF	Davies-Meyer, RMX, Digital signatures, Hash functions
12	Hiromi Yoshida, Naoki Tanaka	A Binarization Method for a Scenery Image with the Fractal Dimension.	CIARP	2009	DBLP DOI BibTeX RDF	Blanket method, Fractal dimension, Binarization
12	Takahiro Matsuda 0002, Kanta Matsuura, Jacob C. N. Schuldt	Efficient Constructions of Signcryption Schemes and Signcryption Composability.	INDOCRYPT	2009	DBLP DOI BibTeX RDF	multi-user security, signcryption, generic construction
12	John O'Donoghue, John Herbert, Philip O'Reilly, David Sammon	Towards Improved Information Quality: The Integration of Body Area Network Data within Electronic Health Records.	ICOST	2009	DBLP DOI BibTeX RDF	Body Area Networks and Data Quality, Electronic Health Records
12	Emre Tuncer, Jordi Cortadella, Luciano Lavagno	Enabling adaptability through elastic clocks.	DAC	2009	DBLP DOI BibTeX RDF	low power design, GALS, desynchronization, adaptive voltage scaling
12	Anand Rangarajan 0001, Karthik S. Gurumoorthy	A Schrödinger Wave Equation Approach to the Eikonal Equation: Application to Image Analysis.	EMMCVPR	2009	DBLP DOI BibTeX RDF
12	Hannu Olkkonen, Juuso T. Olkkonen	Simplified biorthogonal discrete wavelet transform for VLSI architecture design.	Signal Image Video Process.	2008	DBLP DOI BibTeX RDF	Biorthogonal discrete wavelet transform, VLSI, Lifting scheme
12	Ryusuke Sagawa, Katsushi Ikeuchi	Hole Filling of a 3D Model by Flipping Signs of a Signed Distance Field in Adaptive Resolution.	IEEE Trans. Pattern Anal. Mach. Intell.	2008	DBLP DOI BibTeX RDF	interpolation of a mesh model, adaptive signed distance field, 3D modeling
12	Haibin Huang, Pasi Fränti, Dong-Yan Huang, Susanto Rahardja	Cascaded RLS-LMS Prediction in MPEG-4 Lossless Audio Coding.	IEEE Trans. Speech Audio Process.	2008	DBLP DOI BibTeX RDF
12	Su-Wan Park, Sang-Uk Shin	Combined Scheme of Encryption and Watermarking in H.264/Scalable Video Coding (SVC).	New Directions in Intelligent Interactive Multimedia	2008	DBLP DOI BibTeX RDF	Authentication, Watermarking, Contents protection, H.264/SVC
12	Akihiro Yoshida, Hideyuki Mizuno, Kazunori Mano	Segment selection method based on tonal validity evaluation using machine learning for concatenative speech synthesis.	ICASSP	2008	DBLP DOI BibTeX RDF
12	Yu Liu 0062, Gang Tao	Multivariable MRAC using Nussbaum gains for aircraft with abrupt damages.	CDC	2008	DBLP DOI BibTeX RDF
12	Wei You, Sidney S. Fels, Rodger Lea	Studying vision-based multiple-user interaction with in-home large displays.	HCC	2008	DBLP DOI BibTeX RDF	interactive large display, screen real-estate management, tracking, multi-user
12	Young-Joon Oh, Keechul Jung	Vision-based Korean Manual Alphabet recognition game for beginners.	Advances in Computer Entertainment Technology	2008	DBLP DOI BibTeX RDF
12	Makiko Aoyagi, Tsuyoshi Abe, Kenji Takahashi	Symmetric identity federation for fixed-mobile convergence.	Digital Identity Management	2008	DBLP DOI BibTeX RDF	SAML v2.0, fixed-mobile convergence, authentication, identity federation
12	Savithri Sundareswaran, Lucie Nechanicka, Rajendran Panda, Sergey Gavrilov, Roman A. Solovyev, Jacob A. Abraham	A timing methodology considering within-die clock skew variations.	SoCC	2008	DBLP DOI BibTeX RDF
12	Michalis Potamias, Vassilis Athitsos	Nearest neighbor search methods for handshape recognition.	PETRA	2008	DBLP DOI BibTeX RDF	BoostMap, DBH, distance-based hashing, hand pose estimation, embeddings, gesture recognition, hash-based indexing
12	Petros Boufounos, Richard G. Baraniuk	1-Bit compressive sensing.	CISS	2008	DBLP DOI BibTeX RDF
12	Duo Liu, Ping Luo, Yiqi Dai	Attack on Digital Multi-Signature Scheme Based on Elliptic Curve Cryptosystem.	J. Comput. Sci. Technol.	2007	DBLP DOI BibTeX RDF	cryptography, digital signature, elliptic curve, multi-signature
12	Xinyi Huang 0001, Willy Susilo, Yi Mu 0001, Futai Zhang	Breaking and Repairing Trapdoor-Free Group Signature Schemes from Asiacrypt'2004.	J. Comput. Sci. Technol.	2007	DBLP DOI BibTeX RDF	cryptography, digital signature, information security
12	Jingnong Yang, Douglas B. Williams	Transmission Subspace Tracking for MIMO Systems With Low-Rate Feedback.	IEEE Trans. Commun.	2007	DBLP DOI BibTeX RDF
12	Kannan Karthik, Dimitrios Hatzinakos	A novel anti-collusion coding scheme tailored to track linear collusions.	IAS	2007	DBLP DOI BibTeX RDF
12	Evangelos Kotsovinos, Ingo Friese, Martin Kurze, Jörg Heuer	A Role-Based Architecture for Seamless Identity Management and Effective Task Separation.	SEC	2007	DBLP DOI BibTeX RDF
12	Xiaofeng Chen 0001, Fangguo Zhang, Willy Susilo, Yi Mu 0001	Efficient Generic On-Line/Off-Line Signatures Without Key Exposure.	ACNS	2007	DBLP DOI BibTeX RDF	On-line/off-line signatures, Key exposure, Chameleon hashing
12	F. Javier Bueno, M. Goretti Alonso, José Raúl Fernández del Castillo	Assisting lecturers to adapt e-learning content for deaf students.	ITiCSE	2007	DBLP DOI BibTeX RDF	literacy skills, e-learning, content adaptation, deafness
12	Sebastian Ullrich 0001, Jakob Valvoda, Marc Wolter, Gisela Fehrmann, Isa Werth, Ludwig Jaeger, Torsten W. Kuhlen	A Virtual Reality-Based Framework for Experiments on Perception of Manual Gestures.	Gesture Workshop	2007	DBLP DOI BibTeX RDF
12	Hugo Mercier, Julien Peyras, Patrice Dalle	Occluded Facial Expression Tracking.	SCIA	2007	DBLP DOI BibTeX RDF	inverse compositional, tracking, occlusion, facial expression, Active Appearance Model
12	Michael May 0005, Johannes Petersen	The Design Space of Information Presentation: Formal Design Space Analysis with FCA and Semiotics.	ICCS	2007	DBLP DOI BibTeX RDF
12	Takahiro Matsuda 0002, Nuttapong Attrapadung, Goichiro Hanaoka, Kanta Matsuura, Hideki Imai	A CDH-Based Strongly Unforgeable Signature Without Collision Resistant Hash Function.	ProvSec	2007	DBLP DOI BibTeX RDF	target collision resistant hash function, digital signature, standard model, strong unforgeability
12	Takashi Onoda, Norihiko Ito, Hironobu Yamasaki	One-Class SVM based Unusual Condition Monitoring for Risk Management of Hydroelectric Power Plants.	IJCNN	2007	DBLP DOI BibTeX RDF
12	Alexander A. Sherstov	Halfspace Matrices.	CCC	2007	DBLP DOI BibTeX RDF
12	N. R. Sunitha, B. B. Amberker, Prashant Koulgi	Controlled Delegation in e-cheques Using Proxy Signatures.	EDOC	2007	DBLP DOI BibTeX RDF	Se- curity, Digital Signature, Proxy Signature, DSA
12	Dimitrios I. Diochnos, Ioannis Z. Emiris, Elias P. Tsigaridas	On the complexity of real solving bivariate systems.	ISSAC	2007	DBLP DOI BibTeX RDF	real algebraic number, realsolving, topology of real algebraic curve, maple, polynomial system
12	Soroush Abbaspour, Massoud Pedram, Amir H. Ajami, Chandramouli V. Kashyap	Fast Interconnect and Gate Timing Analysis for Performance Optimization.	IEEE Trans. Very Large Scale Integr. Syst.	2006	DBLP DOI BibTeX RDF
12	Chang-Hong Fu 0002, Yui-Lam Chan, Wan-Chi Siu	Efficient reverse-play algorithms for MPEG video with VCR support.	IEEE Trans. Circuits Syst. Video Technol.	2006	DBLP DOI BibTeX RDF
12	Xi-Lin Li, Xian-Da Zhang	A Family of Generalized Constant Modulus Algorithms for Blind Equalization.	IEEE Trans. Commun.	2006	DBLP DOI BibTeX RDF
12	Marlene Hilzensauer	Information Technology for Deaf People.	Intelligent Paradigms for Assistive and Preventive Healthcare	2006	DBLP DOI BibTeX RDF
12	Charles G. Boncelet Jr.	Lossless Image Compression with BCTW.	ICIP	2006	DBLP DOI BibTeX RDF
12	Sébastien Mériaux, Alexis Roche, Bertrand Thirion, Ghislaine Dehaene-Lambertz	Robust statistics for nonparametric group analysis in fMRI.	ISBI	2006	DBLP DOI BibTeX RDF
12	Jean-Bernard Fischer, Emmanuel Prouff	Off-Line Group Signatures with Smart Cards.	CARDIS	2006	DBLP DOI BibTeX RDF	smart card, risk management, Group signature, revocation, dynamic group
12	Jung-Hyun Kim 0006, Kwang-Seok Hong	Speech and Gesture Recognition-Based Robust Language Processing Interface in Noise Environment.	IDEAL	2006	DBLP DOI BibTeX RDF
12	Ronald L. Rivest, Adi Shamir, Yael Tauman	How to Leak a Secret: Theory and Applications of Ring Signatures.	Essays in Memory of Shimon Even	2006	DBLP DOI BibTeX RDF
12	Takashi Onoda, Norihiko Ito, Kenji Shimizu	Unusual Condition Detection of Bearing Vibration in Hydroelectric Power Plants for Risk Management.	JSAI	2006	DBLP DOI BibTeX RDF
12	Benjamín R. C. Bedregal, Antônio Carlos da Rocha Costa, Graçaliz Pereira Dimuro	Fuzzy Rule-Based Hand Gesture Recognition.	IFIP AI	2006	DBLP DOI BibTeX RDF
12	John O'Donoghue, John Herbert	Profile Based Sensor Data Acquisition in a Ubiquitous Medical Environme.	PerCom Workshops	2006	DBLP DOI BibTeX RDF
12	Boguslaw Cyganek	Recognition of Road Signs with Mixture of Neural Networks and Arbitration Modules.	ISNN (2)	2006	DBLP DOI BibTeX RDF
12	Luca Chittaro, Fabio Buttussi, Daniele Nadalutti	MAge-AniM: a system for visual modeling of embodied agent animations and their replay on mobile devices.	AVI	2006	DBLP DOI BibTeX RDF	visual animation modeling, mobile devices, embodied agents
12	Jung-Hyun Kim 0006, Kwang-Seok Hong	MMSDS: Ubiquitous Computing and WWW-Based Multi-modal Sentential Dialog System.	EUC	2006	DBLP DOI BibTeX RDF
12	Mike Wald	Captioning for Deaf and Hard of Hearing People by Editing Automatic Speech Recognition in Real Time.	ICCHP	2006	DBLP DOI BibTeX RDF
12	Antti Raike	Searching Knowledge CinemaSense as a Case Study in Collaborative Production of a WWW Service in Two Universities.	ICCHP	2006	DBLP DOI BibTeX RDF
12	Yoshinori Takeuchi, Yudai Sakashita, Daisuke Wakatsuki, Hiroki Minagawa, Noboru Ohnishi	Communication Supporting System in a Classroom Environment for the Hearing Impaired.	ICCHP	2006	DBLP DOI BibTeX RDF
12	Yuichi Komano, Kazuo Ohta, Atsushi Shimbo, Shin-ichi Kawamura	Toward the Fair Anonymous Signatures: Deniable Ring Signatures.	CT-RSA	2006	DBLP DOI BibTeX RDF
12	Gansen Zhao, Sassa Otenko, David W. Chadwick	Distributed Key Management for Secure Role based Messaging.	AINA (1)	2006	DBLP DOI BibTeX RDF
12	Alexander V. Mirgorodskiy, Naoya Maruyama, Barton P. Miller	Scalable systems software - Problem diagnosis in large-scale computing environments.	SC	2006	DBLP DOI BibTeX RDF
12	Nick Barnes, Gareth Loy, David Shaw, Antonio Robles-Kelly	Regular Polygon Detection.	ICCV	2005	DBLP DOI BibTeX RDF
12	Giuseppe Ateniese, Susan Hohenberger	Proxy re-signatures: new definitions, algorithms, and applications.	CCS	2005	DBLP DOI BibTeX RDF	authenticating path in network, proxy re-signature, bilinear maps
12	Jusak Jusak, Zahir M. Hussain	Performance of Sinusoidally-Distributed Dithering for Signed-Error Constant Modulus Algorithm.	ICITA (2)	2005	DBLP DOI BibTeX RDF
12	Kirsten Ellis	Tools for Inclusive Play: Developing "Auslan for Kinder".	ICITA (2)	2005	DBLP DOI BibTeX RDF
12	Petr Kolman	Approximating Reversal Distance for Strings with Bounded Number of Duplicates.	MFCS	2005	DBLP DOI BibTeX RDF
12	Lei Xu 0001	One-Bit-Matching ICA Theorem, Convex-Concave Programming, and Combinatorial Optimization.	ISNN (1)	2005	DBLP DOI BibTeX RDF
12	Lihua Wang 0001, Eiji Okamoto, Ying Miao 0001, Takeshi Okamoto, Hiroshi Doi	ID-Based Series-Parallel Multisignature Schemes for Multi-Messages from Bilinear Maps.	WCC	2005	DBLP DOI BibTeX RDF
12	Li-Hsun Chen, Oscal T.-C. Chen, Teng-Yi Wang, Yung-Cheng Ma	A multiplication-accumulation computation unit with optimized compressors and minimized switching activities.	ISCAS (6)	2005	DBLP DOI BibTeX RDF
12	Sun Kook Yoo, Seok Myung Jung, B. S. Kim, H. Y. Yun, Sung Rim Kim, Dong Keun Kim	Prototype Design of Mobile Emergency Telemedicine System.	ICCSA (2)	2005	DBLP DOI BibTeX RDF
12	Xiangguo Cheng, Jingmei Liu, Xinmei Wang	Identity-Based Aggregate and Verifiably Encrypted Signatures from Bilinear Pairing.	ICCSA (4)	2005	DBLP DOI BibTeX RDF
12	Razvan V. Florian	A Reinforcement Learning Algorithm for Spiking Neural Networks.	SYNASC	2005	DBLP DOI BibTeX RDF
12	Xinyi Huang 0001, Willy Susilo, Yi Mu 0001, Futai Zhang	Identity-Based Ring Signcryption Schemes: Cryptographic Primitives for Preserving Privacy and Authenticity in the Ubiquitous World.	AINA	2005	DBLP DOI BibTeX RDF
12	Dimitrios I. Kosmopoulos	Automated Extraction of Object- and Event-Metadata from Gesture Video Using a Bayesian Network.	ICANN (2)	2005	DBLP DOI BibTeX RDF
12	Tim Fox, Lou Covey, Susan Mack, David Heacock, Ed P. Huijbregts, Vess Johnson, Avner Kornfeld, Andrew Yang, Paul S. Zuchowski	Should our power approach be current?	DAC	2005	DBLP DOI BibTeX RDF	low-power design, energy consumption, power analysis, leakage current, dynamic power, static power
12	Jie Yang 0010, Luigi Capodieci, Dennis Sylvester	Advanced timing analysis based on post-OPC extraction of critical dimensions.	DAC	2005	DBLP DOI BibTeX RDF	process CD, layout, OPC, design flow
12	Bharat K. Bhargava, Changgui Shi, Sheng-Yih Wang	MPEG Video Encryption Algorithms.	Multim. Tools Appl.	2004	DBLP DOI BibTeX RDF	multimedia data security, MPEG video encryption, MPEG codec