The Experts below are selected from a list of 960 Experts worldwide ranked by ideXlab platform
Lajos Hanzo - One of the best experts on this subject based on the ideXlab platform.
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Burst-by-burst adaptive joint detection CDMA/H.263 based video telephony
IEEE Transactions on Circuits and Systems for Video Technology, 2002Co-Authors: Peter Cherriman, E.l. Kuan, Lajos HanzoAbstract:Since wireless channels exhibit dramatic near-instantaneous channel-quality fluctuations, it is unrealistic to expect that a transceiver relying on time-invariant modulation and coding modes is capable of delivering as good a performance as a near-instantaneously adaptive arrangement. Hence, a near-instantaneously adaptive joint-detection code division multiple access (CDMA)-based video transceiver is proposed for wireless video telephony. Specifically, the transceiver is capable of reconfiguring itself in 1, 2 and 4 bits/symbol direct-sequence CDMA modes and delivers an unimpaired video quality associated with a peak signal-to-noise ratio (PSNR) of 34-41 dB for channel SNRs in excess of about 5 dB over the COST207 bad urban channel model at video rates between 5-26.9 kbits/s using 176/spl times/144 pixel quarter common intermediate format (QCIF) and 128/spl times/96 pixel sub-QCIF (SQCIF) video formats.
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Burst-by-burst adaptive wideband wireless video telephony
IEEE Benelux Chapter on Vehicular Technology and Communications. Symposium on Communications and Vehicular Technology. SCVT-2000. Proceedings (Cat. No, 2000Co-Authors: Lajos Hanzo, C. H Wong, Peter CherrimanAbstract:The design trade-offs of interactive wireless video systems are discussed and performance comparisons are provided both in the context of second- and third-generation wireless videophone systems. We commence our discussions by a comparative study of arbitrarily programmable, but fixed-rate, videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s. These proprietary codecs were designed to allow direct replacement of mobile radio voice codecs in second generation wireless systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems, operating at 13, 8, 9.6 and 6.7 kbps, respectively, although better video quality is maintained over higher-rate, 32 kbps cordless systems, such as the Japanese PHS and the European DECT and CT2 systems. From the range of codecs investigated, best overall performance was achieved by our vector-quantised codecs, followed by the discrete cosine transformed and the quadtree-based schemes. The associated video peak signal-to-noise ratio (PSNR) was around 30 dB, while the subjective video quality can be assessed under http://www-mobile.ecs.soton.ac.uk. A range of multimode wireless transceivers is also proposed. The second part of the paper is dedicated to burst-by-burst (BbB) adaptive wireless video transceivers employing the standard H.263 codec. It is demonstrated that the proposed BbB adaptive transceivers provide an improved video performance in comparison to their statically reconfigured counterparts in the context of both wideband BbB adaptive quadrature amplitude modulation (AQAM) transceivers and the joint-detection based code division multiple access (CDMA) transceivers of the third generation systems.
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Oscillation-scaled histogram-based Markov modelling of video codecs for multiple access
IEEE GLOBECOM 1998 (Cat. NO. 98CH36250), 1998Co-Authors: M. Del Buono, Lajos Hanzo, Peter CherrimanAbstract:A model is proposed for replacing the video codec in networking studies, which is tested for sources with a mean bit rate in the range of 10 kb/s to 10 Mb/s. The standard frame sizes investigated are the International Telecommunications Union's (ITU) 352/spl times/352-pixel common intermediate format (CIF), 176/spl times/144-pixel quarter CIF (QCIF), 704/spl times/576 pixel 4CIF and 128/spl times/96-pixel sub-QCIF (SQCIF). The proposed 2O-state 'oscillation-scaled' Markov model was found to represent the relevant video codec characteristics adequately.
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Multi-frame packet reservation multiple access using oscillation-scaled histogram-based Markov modelling of video codecs
Signal Processing-image Communication, 1998Co-Authors: J. Brecht, M. Del Buono, Lajos HanzoAbstract:Abstract A model is proposed for replacing the video codec in networking studies, which is tested for sources with a mean bit-rate in the range of 10 Kb/s to 10 Mb/s. The standard frame sizes investigated are the International Telecommunications Union’s (ITU) 352×288-pixel common intermediate format (CIF), 176×144-pixel Quarter CIF (QCIF), 704×576-pixel 4CIF and 128×96-pixel Sub-QCIF (SQCIF). The proposed 20-state ‘oscillation-scaled’ Markov model was found to represent the relevant video codec characteristics adequately. The performance of this model is then tested in the context of a novel Multi-frame Packet Reservation Multiple Access or MF-PRM A scheme, which is shown in Fig. 17 to outperform conventional PRMA in terms of both its delay and packet dropping performance, reaching throughput values as high as 79%.
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Comparison of fixed-rate video codecs for wireless videophony
1997 IEEE 47th Vehicular Technology Conference. Technology in Motion, 1997Co-Authors: Jurgen Streit, Lajos HanzoAbstract:Gain-cost quantised, fixed but arbitrarily programmable rate discrete cosine transformed (DCT) video codecs, vector-quantised (VQ) and quad-tree (QT) coding algorithms are proposed and their video quality, complexity, compression ratio and error resilience trade-offs are comparatively analysed under identical conditions. Our candidate codecs are compared to the standard H261 and MPEG-2 benchmark codecs. The proposed codecs facilitate wireless videophony for quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s at rates around 10 kbps in second-generation mobile systems.
Nouri Masmoudi - One of the best experts on this subject based on the ideXlab platform.
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a reduced reference video quality assessment of h 264 and mpeg2 codec based on sharpness metric
2016Co-Authors: Mohamed Ben Amor, Fahmi Kammoun, Mohamed-chaker Larabi, Nouri MasmoudiAbstract:In this paper, we propose a new perceptually significant video quality metric for the H.264/Motion Picture Expert Group (MPEG)-4 Advanced Video Coding (AVC) and MPEG2 standard. Ourmethod operates in the spatial domain by using the Sobel filter. The proposed approach does notrequire a high computational complexity and can be suitable for real-time evaluation. We evaluatethe performance of the proposed method by using three common intermediate format sequences at dif-ferent compression rates. The comparison of the obtained results is made with some video qualitymodels using “LIVE”, “IVP” and “IRCCyN/IVC 1080i” databases. The performance metrics, i.e. Pearson and Spearman correlation coefficients, indicate that the proposed method gives a good performance inH264 and MPEG2 codec distortions with the three databases comparing with other models.
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Real-time H264/AVC encoder based on enhanced frame level parallelism for smart multicore DSP camera
Journal of Real-Time Image Processing, 2016Co-Authors: Nejmeddine Bahri, Nouri Masmoudi, Mohamed Ali Ben Ayed, Thierry Grandpierre, Nidhameddine Belhadj, Mohamed AkilAbstract:The latest generation of multicore digital signal processors (DSP), their high computing power, low consumption, and integrated peripherals will allow them to be embedded in the next generation of smart camera. Such DSPs allow designers to evolve the vision landscape and simplify the developer’s tasks to run more complex image and video processing applications without the need to burden a separate personal computer. This paper explains the exploitation of the computing power of a multicore DSP TMS320C6472 to implement a real-time H264/AVC video encoder. This work can be considered as a milestone for the implementation of the new High Efficiency Video Coding standard (HEVC-H265). In fact, to improve the encoding speed, enhanced Frame Level Parallelism (FLP) approach is presented and implemented. A real-time fully functional video demo is given, taken into account video capture and bitstream storage. Experimental results show how we efficiently exploit the potentials and the features of the multicore platform without inducing video quality degradation in terms of PSNR or bitrate increase. The enhanced FLP using five DSP cores achieves a speedup factor of more than four times in average compared to a mono-core implementation for common intermediate format (CIF 352 × 288), Standard Definition (SD 720 × 480), and High Definition (HD 1280 × 720) resolutions. This optimized implementation allows us to meet the real-time compliant by reaching an encoding speed of 99 f/s (frame/second) and 30 f/s for CIF and SD resolutions respectively, and saves up to 77 % of encoding time for HD resolution.
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A reduced reference video quality assessment of H.264 and mpeg2 codec based on sharpness metric: Video quality based on sharpness metric
Journal of The Society for Information Display, 2016Co-Authors: Mohamed Ben Amor, Fahmi Kammoun, Mohamed-chaker Larabi, Nouri MasmoudiAbstract:International audienceIn this paper, we propose a new perceptually significant video quality metric for the H.264/Motion Picture Expert Group (MPEG)-4 Advanced Video Coding (AVC) and MPEG2 standard. Ourmethod operates in the spatial domain by using the Sobel filter. The proposed approach does notrequire a high computational complexity and can be suitable for real-time evaluation. We evaluatethe performance of the proposed method by using three common intermediate format sequences at dif-ferent compression rates. The comparison of the obtained results is made with some video qualitymodels using “LIVE”, “IVP” and “IRCCyN/IVC 1080i” databases. The performance metrics, i.e. Pearson and Spearman correlation coefficients, indicate that the proposed method gives a good performance inH264 and MPEG2 codec distortions with the three databases comparing with other models
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GOP level parallelism implementation for real-time H264/AVC video encoder on multicore DSP TMS320C6472
2014 6th European Embedded Design in Education and Research Conference (EDERC), 2014Co-Authors: Nejmeddine Bahri, Nouri Masmoudi, Thierry Grandpierre, Med Ali Ben Ayed, Mohamed AkilAbstract:In this paper, we exploit the parallelism offered by six-core Digital Signal Processor (DSP) TMS320C6472 to implement the H264/AVC video encoder in order to meet the real-time constraint for different video resolutions. To enhance the encoding speed, GOP Level Parallelism approach is implemented on 5 slave DSP cores. A master core is reserved to manage data transfers among DSP memory and personal computer in order to perform a real-time video encoding demo taken into account video capture and bit-stream storage. Multithreading algorithm and ping-pong buffers technique are used in order to optimize the communication overhead. Experimental results show that our enhanced implementation allows to overcome the real-time constraint by reaching up to 120 f/s (frame/second) for common intermediate format resolution (CIF 352×288) and 35f/s for Standard Definition (SD 720×480). Our proposed approach can save about 80% of run-time for High Definition resolution (HD 1280×720). The Enhanced GOP Level parallelism approach on five DSP cores achieves a good average speedup factor of 4.88 without inducing any quality degradation or bit-rate increment.
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A Perceptual Measure of Blocking Artifact for No-reference Video Quality Evaluation of H.264 Codec
Journal of Testing and Evaluation, 2014Co-Authors: Mohamed Ben Amor, Fahmi Kammoun, Mohamed-chaker Larabi, Nouri MasmoudiAbstract:In this paper, we propose a new, perceptually significant video quality metric to estimate the blocking effect caused by the H.264/MPEG-4 Advanced Video Coding (AVC) standard. Our method operates in the spatial domain by taking into account the local variation inside each 16 by 16 block. The proposed approach does not require high computational complexity and can be suitable for real-time evaluation. We evaluate the performance of the proposed method by using three common intermediate format sequences at different compression rates. The comparison of the obtained results was made with Suthaharan's technique using the IVP database. The performance metrics, Pearson and Spearman correlation coefficients, indicate that the proposed method outperformed the approach recommended in the literature for block-based compression, and the improvement was even better for the H.264/MPEG-4 AVC standard.
Jurgen Streit - One of the best experts on this subject based on the ideXlab platform.
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Comparison of fixed-rate video codecs for wireless videophony
1997 IEEE 47th Vehicular Technology Conference. Technology in Motion, 1997Co-Authors: Jurgen Streit, Lajos HanzoAbstract:Gain-cost quantised, fixed but arbitrarily programmable rate discrete cosine transformed (DCT) video codecs, vector-quantised (VQ) and quad-tree (QT) coding algorithms are proposed and their video quality, complexity, compression ratio and error resilience trade-offs are comparatively analysed under identical conditions. Our candidate codecs are compared to the standard H261 and MPEG-2 benchmark codecs. The proposed codecs facilitate wireless videophony for quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s at rates around 10 kbps in second-generation mobile systems.
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Multi-Mode Wireless Videophony
1997Co-Authors: Lajos Hanzo, Jurgen StreitAbstract:A comparative study of arbitrarily programmable, but fixed-rate videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s is offered. These codecs were designed to allow direct replacement of mobile radio voice codecs in second generation wireless systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems, operating at 13, 8, 9.6 and 6.7 kbps, respectively, although better video quality is maintained over higher-rate, 32kbps cordless systems, such as the Japanese PHS and the European DECT and CT2 systems. Best overall performance was achieved by our vector-quantised codecs, followed by the discrete cosine transformed and the quadtree-based schemes, which were characterised by the bit allocation schemes of Table 1. The associated video Peak Signal-to-Noise Ratio (PSNR) was around 30 dB, while the subjective quality can be viewed under http://www-mobile.ecs.soton.ac.uk. A range of multimode wireless transceivers were also proposed, which are characterised by Table 2.
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Vector-quantised cordless videophone transceivers
Proceedings of GLOBECOM'96. 1996 IEEE Global Telecommunications Conference, 1996Co-Authors: Jurgen Streit, Lajos HanzoAbstract:A variety of adaptively re-configurable wireless videophone transceivers are proposed and their video quality, bit rate, robustness and complexity issues are analysed. A suite of fixed but arbitrarily programmable low-rate, perceptually weighted vector quantised (VQ) codecs with and without run-length compression (RLC) are contrived for quarter common intermediate format (QCIF) videophone sequences. The 11.36 kbps codec 1 is BCH(127,71,9) coded to a rate of 20.32 kbps and this arrangement is comparatively studied along with the 8 kbps codec 2 and BCH(127,50,13) scheme, which has the same 20.32 kbps overall rate. The source-sensitivity matched systems 1-6 characterised in a table were contrived to comparatively study the range of system design options. For example, using codec 1 in system 1 and coherent pilot symbol assisted 16-level quadrature amplitude modulation (16-PSAQAM), an overall signalling rate of 9 kBd was yielded. Over lower quality channels the 4QAM mode of operation had to be invoked, which required twice as many time slots to accommodate the resulting 18 kBd stream. The robustness of systems 2, 3, 4 and 6 was increased using automatic repeat requests (ARQ), inevitably reducing the number of users supported, which was between 6 and 16. In a bandwidth of 200 kHz, similarly to the Pan-European GSM mobile radio system's speech channel, using systems 1, 3, 4 or 5 for example, 16 and 8 videophone users can be supported in the 16 QAM and 4 QAM modes, respectively. The basic system characteristics are highlighted.
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Fixed-rate video codecs for wireless systems
Proceedings of First International Workshop on Wireless Image Video Communications, 1996Co-Authors: Jurgen Streit, Lajos HanzoAbstract:A comparative study of arbitrarily programmable, but fixed-rate videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s is offered. These codecs were designed to allow direct replacement of mobile radio voice codecs in second generation wireless systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems, operating at 13, 8, 9.6 and 6.7 kbps, respectively.
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Quadtree-decomposed cordless videophones
Proceedings of Vehicular Technology Conference - VTC, 1996Co-Authors: Jurgen Streit, Lajos HanzoAbstract:Arbitrarily programmable, but fixed-rate quad-tree (QT) decomposed, parametrically enhanced videophone codecs using quarter common intermediate format (QCIF) video sequences are proposed as a direct replacement for mobile radio voice codecs in second generation systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems. The proposed 11.36 kbps codec 1 and the 11 kbps codec 2 are embedded in the adaptively re-configurable wireless videophone systems 1-4 featured in a table and their video quality, bit rate, robustness and complexity issues are investigated. Coherent re-configurable 16 or 4-level pilot symbol assisted quadrature amplitude modulation (PSAQAM) is used and the system's robustness is improved by a combination of diversity and automatic repeat request (ARQ) techniques. When using a bandwidth of 200 kHz, as in the pan-European GSM mobile radio system, the number of videophone users supported varies between 3 and 16, while the minimum required channel signal to noise ratio over Gaussian and Rayleigh channels is in excess of 6 and 8 dB, respectively. The salient system features are summarised in a table.
Zhong Shao - One of the best experts on this subject based on the ideXlab platform.
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Typed common intermediate format
ACM Sigsoft Software Engineering Notes, 2000Co-Authors: Zhong ShaoAbstract:Application languages are very e ective in solving speci c software problems. Unfortunately, they pose great challenges to reliable and e cient implementations. In fact, most existing application languages are slow, interpreted, and have poor interoperability with general-purpose languages. This paper presents a framework on building highquality systems environment for multiple advanced languages. Our key innovation is the use of a common typed intermediate language, named FLINT, to model the semantics and interactions of various language-speci c features. FLINT is based on a predicative variant of the Girard-Reynolds polymorphic calculus F!, extended with a very rich set of primitive types and functions. FLINT provides a common compiler infrastructure that can be quickly adapted to generate compilers for new general-purpose and domain-speci c languages. With its single uni ed type system, FLINT serves as a great platform for reasoning about crosslanguage interoperations. FLINT types act as a glue to connect language features that complicate interoperability, such as mixed data representations, multiple function calling conventions, and di erent memory management protocols. In addition, because all runtime representations are determined by FLINT types, languages compiled under FLINT can share the same system-wide garbage collector and foreign function call interface.
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DSL - Typed common intermediate format
1997Co-Authors: Zhong ShaoAbstract:Application languages are very effective in solving specific software problems. Unfortunately, they pose great challenges to reliable and efficient implementations. In fact, most existing application languages are slow, interpreted, and have poor interoperability with general-purpose languages. This paper presents a framework on building high-quality systems environment for multiple advanced languages. Our key innovation is the use of a common typed intermediate language, named FLINT, to model the semantics and interactions of various language-specific features. FLINT is based on a predicative variant of the Girard-Reynolds polymorphic calculus Fω, extended with a very rich set of primitive types and functions. FLINT provides a common compiler infrastructure that can be quickly adapted to generate compilers for new general-purpose and domain-specific languages. With its single unified type system, FLINT serves as a great platform for reasoning about cross-language interoperations. FLINT types act as a glue to connect language features that complicate interoperability, such as mixed data representations, multiple function calling conventions, and different memory management protocols. In addition, because all runtime representations are determined by FLINT types, languages compiled under FLINT can share the same system-wide garbage collector and foreign function call interface.
Peter Cherriman - One of the best experts on this subject based on the ideXlab platform.
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Burst-by-burst adaptive joint detection CDMA/H.263 based video telephony
IEEE Transactions on Circuits and Systems for Video Technology, 2002Co-Authors: Peter Cherriman, E.l. Kuan, Lajos HanzoAbstract:Since wireless channels exhibit dramatic near-instantaneous channel-quality fluctuations, it is unrealistic to expect that a transceiver relying on time-invariant modulation and coding modes is capable of delivering as good a performance as a near-instantaneously adaptive arrangement. Hence, a near-instantaneously adaptive joint-detection code division multiple access (CDMA)-based video transceiver is proposed for wireless video telephony. Specifically, the transceiver is capable of reconfiguring itself in 1, 2 and 4 bits/symbol direct-sequence CDMA modes and delivers an unimpaired video quality associated with a peak signal-to-noise ratio (PSNR) of 34-41 dB for channel SNRs in excess of about 5 dB over the COST207 bad urban channel model at video rates between 5-26.9 kbits/s using 176/spl times/144 pixel quarter common intermediate format (QCIF) and 128/spl times/96 pixel sub-QCIF (SQCIF) video formats.
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Burst-by-burst adaptive wideband wireless video telephony
IEEE Benelux Chapter on Vehicular Technology and Communications. Symposium on Communications and Vehicular Technology. SCVT-2000. Proceedings (Cat. No, 2000Co-Authors: Lajos Hanzo, C. H Wong, Peter CherrimanAbstract:The design trade-offs of interactive wireless video systems are discussed and performance comparisons are provided both in the context of second- and third-generation wireless videophone systems. We commence our discussions by a comparative study of arbitrarily programmable, but fixed-rate, videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s. These proprietary codecs were designed to allow direct replacement of mobile radio voice codecs in second generation wireless systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems, operating at 13, 8, 9.6 and 6.7 kbps, respectively, although better video quality is maintained over higher-rate, 32 kbps cordless systems, such as the Japanese PHS and the European DECT and CT2 systems. From the range of codecs investigated, best overall performance was achieved by our vector-quantised codecs, followed by the discrete cosine transformed and the quadtree-based schemes. The associated video peak signal-to-noise ratio (PSNR) was around 30 dB, while the subjective video quality can be assessed under http://www-mobile.ecs.soton.ac.uk. A range of multimode wireless transceivers is also proposed. The second part of the paper is dedicated to burst-by-burst (BbB) adaptive wireless video transceivers employing the standard H.263 codec. It is demonstrated that the proposed BbB adaptive transceivers provide an improved video performance in comparison to their statically reconfigured counterparts in the context of both wideband BbB adaptive quadrature amplitude modulation (AQAM) transceivers and the joint-detection based code division multiple access (CDMA) transceivers of the third generation systems.
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Oscillation-scaled histogram-based Markov modelling of video codecs for multiple access
IEEE GLOBECOM 1998 (Cat. NO. 98CH36250), 1998Co-Authors: M. Del Buono, Lajos Hanzo, Peter CherrimanAbstract:A model is proposed for replacing the video codec in networking studies, which is tested for sources with a mean bit rate in the range of 10 kb/s to 10 Mb/s. The standard frame sizes investigated are the International Telecommunications Union's (ITU) 352/spl times/352-pixel common intermediate format (CIF), 176/spl times/144-pixel quarter CIF (QCIF), 704/spl times/576 pixel 4CIF and 128/spl times/96-pixel sub-QCIF (SQCIF). The proposed 2O-state 'oscillation-scaled' Markov model was found to represent the relevant video codec characteristics adequately.