The Experts below are selected from a list of 1929 Experts worldwide ranked by ideXlab platform
Pamela C. Cosman - One of the best experts on this subject based on the ideXlab platform.
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Delay Constrained Multiplexing of Video Streams Using Dual-Frame Video Coding
IEEE Transactions on Image Processing, 2010Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:We consider the multiplexing problem of transmitting multiple video source streams from a server over a shared channel. We use Dual-Frame video coding with high-quality Long-Term Reference (LTR) Frames and propose multiplexing methods to reduce the sum of mean squared error for all the video streams. This paper makes several improvements to Dual-Frame video coding. A simple motion activity detection algorithm is used to choose the location of LTR Frames as well as the number of bits given to such Frames. An adaptive buffer-constrained rate-control algorithm is devised to accommodate the extra bits of the high-quality LTR Frames. Multiplexing of video streams is studied under the constraint of a video encoder delay buffer. Using H.264/AVC, the results show considerable improvement over baseline schemes such as H.264 rate control when the video streams are encoded indiviDually and over multiplexing methods proposed previously in the literature. The high-quality LTR Frames are offset in time among different video streams. This provides the benefits of Dual-Frame coding with high-quality LTR Frames while still fitting under the constraint of an output delay buffer.
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ICIP - Buffer constrained rate control for low bitrate Dual-Frame video coding
2008 15th IEEE International Conference on Image Processing, 2008Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:In Dual-Frame video coding, one long-term reference (LTR) and one short-term reference (STR) Frames are used for motion estimation and compensation. In previous work, it was shown that the performance of video coding can be improved by pulsing the quality of LTR Frames in Dual-Frame video coding, but this increases the encoder delay buffer size. Also, buffer constrained real-time video transmission requires an efficient rate control algorithm to meet the delay requirement. In this paper, we propose a rate control algorithm for Dual- Frame video coding under a delay buffer constraint. With the proposed rate control algorithm and motion activity detection for determining the LTR quality, simulation results using H.264/AVC show a significant PSNR improvement over H.264 rate control and other rate control algorithms for Dual- Frame video coding.
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ICASSP - Multiplexing video streams using Dual-Frame video coding
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:We consider the transmission of multiple video source streams over a shared channel from a server. Using the rate-distortion curves and Dual-Frame video coding with high quality long-term reference (LTR) Frames, we propose a method to reduce the sum of mean squared error for all the video streams. A simple motion activity detection algorithm was used to determine the amount of high quality given to the LTR Frames. Using H.264/AVC, the results show considerable improvement over a baseline scheme where each video stream is provided with equal bitrate.
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Dual Frame Motion Compensation With Uneven Quality Assignment
IEEE Transactions on Circuits and Systems for Video Technology, 2008Co-Authors: Vijay Chellappa, Pamela C. Cosman, Geoffrey M. VoelkerAbstract:Video codecs that use motion compensation have shown PSNR gains from the use of multiple Frame prediction, in which more than one past reference Frame is available for motion estimation. In Dual Frame motion compensation, one short-term reference Frame and one long-term reference Frame are available for prediction. In this paper, we explore using Dual Frame motion compensation in two contexts. We first show that using a single fixed long-term reference Frame in the context of a rate switching network can enhance video quality. Next, by periodically creating high-quality long-term reference Frames, we show that the performance is superior to a standard Dual Frame technique that has the same average rate but no high-quality Frames.
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Multiplexing video streams using Dual-Frame video coding
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:We consider the transmission of multiple video source streams over a shared channel from a server. Using the rate-distortion curves and Dual-Frame video coding with high quality long-term reference (LTR) Frames, we propose a method to reduce the sum of mean squared error for all the video streams. A simple motion activity detection algorithm was used to determine the amount of high quality given to the LTR Frames. Using H.264/AVC, the results show considerable improvement over a baseline scheme where each video stream is provided with equal bitrate.
Mayank Tiwari - One of the best experts on this subject based on the ideXlab platform.
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Bit-rate allocation for multiple video streams : Dual-Frame video coding and competitive equilibrium methods
2013Co-Authors: Mayank TiwariAbstract:With the advancement of digital video technology in recent years, there has been an enormous surge in the amount of video data sent across networks. In many cases, a transmission link is shared by more than one video stream. Applications where multiple compressed video streams are transmitted simultaneously through a shared channel include direct broadcast satellite (DBS), cable TV, video- on-demand services, disaster relief response, and video surveillance. Some commercial applications are YouTube and instant video streaming by content providers, such as Netflix, where multiple streams are transmitted simultaneously, and in many cases, these streams share a common transmission channel. Recently, in cognitive radio technology, the secondary or unlicensed users share a pool of bandwidth that is temporarily going unused by the primary or licensed users. In such cases, it has been shown that joint bit-rate allocation schemes for multiple streams can perform better than an equal bit-rate allocation. In this dissertation, we consider the problem of bit-rate allocation for multiple video users sharing a common transmission channel. We consider two separate objectives for bit-rate allocation among multiple video users: (a) improving the video quality averaged across all the users, and (b) improving the video quality of each indiviDual user, compared to the bit-rate allocation for the users when acting independently. We use Dual-Frame video with high-quality Long-Term Reference (LTR) Frames, and propose multiplexing methods to reduce the sum of Mean Squared Error (MSE) for all the users. We make several improvements to Dual-Frame video coding by selecting the location and quality of LTR Frames. An adaptive buffer- constrained rate-control algorithm is devised to accommodate the extra bits of the high-quality LTR Frames. Multiplexing of video streams was studied under the constraint of a video encoder delay buffer. The high- quality LTR Frames are offset in time among different video streams. This provides the benefit of Dual-Frame video coding with high-quality LTR Frames while still fitting under the constraint of an output delay buffer. The multiplexing methods show considerable improvement over conventional rate control when the video streams are encoded independently, and over multiplexing methods proposed previously in the literature. While the average video quality is improved for multiple video users, such methods often rely on identifying the relative complexity of the video streams. In such methods, not all the videos benefit from the multiplexing process. Typically, the quality of high motion videos is improved at the expense of a reduction in the quality of low motion videos. We use a competitive equilibrium allocation of bit-rate to improve the quality of each indiviDual video stream by finding trades between videos across time. A central controller collects rate-distortion information from each video user and makes a joint bit-rate allocation decision. The proposed method uses information about not only the differing complexity of the different video streams at a given instant of time, but also the differing complexity of each stream over time. Using the competitive equilibrium bit-rate allocation approach for multiple video streams, we show that all the video streams perform better or at least as well as with indiviDual encoding. The centralized bit-rate allocation methods share the video characteristics and involve high computational complexity. In our pricing-based method, we present an informationally decentralized bit-rate allocation for multiple users where a user only needs to inform his demand to an allocator. Each user separately calculates his bit-rate demand based on his video complexity and bit- rate price, where the bit-rate price is announced by the allocator. The allocator adjusts the bit-rate price based on
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Delay Constrained Multiplexing of Video Streams Using Dual-Frame Video Coding
IEEE Transactions on Image Processing, 2010Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:We consider the multiplexing problem of transmitting multiple video source streams from a server over a shared channel. We use Dual-Frame video coding with high-quality Long-Term Reference (LTR) Frames and propose multiplexing methods to reduce the sum of mean squared error for all the video streams. This paper makes several improvements to Dual-Frame video coding. A simple motion activity detection algorithm is used to choose the location of LTR Frames as well as the number of bits given to such Frames. An adaptive buffer-constrained rate-control algorithm is devised to accommodate the extra bits of the high-quality LTR Frames. Multiplexing of video streams is studied under the constraint of a video encoder delay buffer. Using H.264/AVC, the results show considerable improvement over baseline schemes such as H.264 rate control when the video streams are encoded indiviDually and over multiplexing methods proposed previously in the literature. The high-quality LTR Frames are offset in time among different video streams. This provides the benefits of Dual-Frame coding with high-quality LTR Frames while still fitting under the constraint of an output delay buffer.
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ICIP - Buffer constrained rate control for low bitrate Dual-Frame video coding
2008 15th IEEE International Conference on Image Processing, 2008Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:In Dual-Frame video coding, one long-term reference (LTR) and one short-term reference (STR) Frames are used for motion estimation and compensation. In previous work, it was shown that the performance of video coding can be improved by pulsing the quality of LTR Frames in Dual-Frame video coding, but this increases the encoder delay buffer size. Also, buffer constrained real-time video transmission requires an efficient rate control algorithm to meet the delay requirement. In this paper, we propose a rate control algorithm for Dual- Frame video coding under a delay buffer constraint. With the proposed rate control algorithm and motion activity detection for determining the LTR quality, simulation results using H.264/AVC show a significant PSNR improvement over H.264 rate control and other rate control algorithms for Dual- Frame video coding.
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ICASSP - Multiplexing video streams using Dual-Frame video coding
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Mayank Tiwari, Theodore Groves, Pamela C. CosmanAbstract:We consider the transmission of multiple video source streams over a shared channel from a server. Using the rate-distortion curves and Dual-Frame video coding with high quality long-term reference (LTR) Frames, we propose a method to reduce the sum of mean squared error for all the video streams. A simple motion activity detection algorithm was used to determine the amount of high quality given to the LTR Frames. Using H.264/AVC, the results show considerable improvement over a baseline scheme where each video stream is provided with equal bitrate.
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Buffer constrained rate control for low bitrate Dual-Frame video coding
2008 15th IEEE International Conference on Image Processing, 2008Co-Authors: Mayank Tiwari, Theodore Groves, Pamela CosmanAbstract:In Dual-Frame video coding, one long-term reference (LTR) and one short-term reference (STR) Frames are used for motion estimation and compensation. In previous work, it was shown that the performance of video coding can be improved by pulsing the quality of LTR Frames in Dual-Frame video coding, but this increases the encoder delay buffer size. Also, buffer constrained real-time video transmission requires an efficient rate control algorithm to meet the delay requirement. In this paper, we propose a rate control algorithm for Dual- Frame video coding under a delay buffer constraint. With the proposed rate control algorithm and motion activity detection for determining the LTR quality, simulation results using H.264/AVC show a significant PSNR improvement over H.264 rate control and other rate control algorithms for Dual- Frame video coding.
Nicolò Speciale - One of the best experts on this subject based on the ideXlab platform.
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Analytical Construction and Fast Computation of Frequency Warping Operators and Dual Frame
IEEE Transactions on Signal Processing, 2014Co-Authors: Salvatore Caporale, Nicolò SpecialeAbstract:Frequency warping has been introduced as a unitary operator over a nonfinite domain. In practical applications, the need of a feasible implementation forces to redefine frequency warping over finite domains in the Framework of redundant transformations called Frames, where the unitary property is replaced by the tight Frame property, i.e., the adjoint operator behaves as pseudo-inverse. In case a tight Frame cannot be designed, inversion can be achieved by finding the Dual Frame. In this work, with reference to nonsmooth warping functions, we present a new approach to the construction and fast computation of the Dual Frame operator based on an operator power series. With respect to previous approaches, many limitations are overcome while maintaining important properties of frequency warping.
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Dual Frame of frequency warping operators
2011 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2011Co-Authors: Salvatore Caporale, Nicolò SpecialeAbstract:In this work we introduce the Dual Frame operator relative to the aliasing compensated frequency warping operator for non-smooth warping functions. Except for approximation errors, the resulting operators pair allows perfect reconstruction. Unlike previously introduced frequency warping Frame and Dual Frame pair, which was obtained by adding redundancy to the group delay shift covariance analysis space, in this case no modifications are needed to the analysis operator. Anyway, to calculate the Dual Frame, previously introduced computational models are exploited and forward developed. Basically, the Dual Frame construction is based on an operator power series which is entirely precomputed, so the complexity of frequency warping inversion is not increased.
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ICASSP - Dual Frame of frequency warping operators
2011 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2011Co-Authors: Salvatore Caporale, Nicolò SpecialeAbstract:In this work we introduce the Dual Frame operator relative to the aliasing compensated frequency warping operator for non-smooth warping functions. Except for approximation errors, the resulting operators pair allows perfect reconstruction. Unlike previously introduced frequency warping Frame and Dual Frame pair, which was obtained by adding redundancy to the group delay shift covariance analysis space, in this case no modifications are needed to the analysis operator. Anyway, to calculate the Dual Frame, previously introduced computational models are exploited and forward developed. Basically, the Dual Frame construction is based on an operator power series which is entirely precomputed, so the complexity of frequency warping inversion is not increased.
Geoffrey M. Voelker - One of the best experts on this subject based on the ideXlab platform.
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Dual Frame Motion Compensation With Uneven Quality Assignment
IEEE Transactions on Circuits and Systems for Video Technology, 2008Co-Authors: Vijay Chellappa, Pamela C. Cosman, Geoffrey M. VoelkerAbstract:Video codecs that use motion compensation have shown PSNR gains from the use of multiple Frame prediction, in which more than one past reference Frame is available for motion estimation. In Dual Frame motion compensation, one short-term reference Frame and one long-term reference Frame are available for prediction. In this paper, we explore using Dual Frame motion compensation in two contexts. We first show that using a single fixed long-term reference Frame in the context of a rate switching network can enhance video quality. Next, by periodically creating high-quality long-term reference Frames, we show that the performance is superior to a standard Dual Frame technique that has the same average rate but no high-quality Frames.
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Dual Frame motion compensation with uneven quality assignment
Data Compression Conference 2004. Proceedings. DCC 2004, 2004Co-Authors: Vijay Chellappa, Pamela C. Cosman, Geoffrey M. VoelkerAbstract:Video codecs that use motion compensation have shown PSNR gains from the use of multiple Frame prediction, in which more than one past reference Frame is available for motion estimation. In Dual Frame motion compensation, one short-term reference Frame and one long-term reference Frame are available for prediction. In this paper, we propose a Dual Frame motion compensation technique that allocates bits unevenly among Frames to periodically create a high-quality Frame that serves as the long-term reference Frame for some time. By modifying an MPEG-4 encoder to use this technique on a set of video sequences, we show that it outperforms a normal Dual Frame motion compensation scheme in which the long-term reference Frames are regular Frames that are not allocated any extra rate.
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Data Compression Conference - Dual Frame motion compensation with uneven quality assignment
Data Compression Conference 2004. Proceedings. DCC 2004, 2004Co-Authors: Vijay Chellappa, Pamela C. Cosman, Geoffrey M. VoelkerAbstract:Video codecs that use motion compensation have shown PSNR gains from the use of multiple Frame prediction, in which more than one past reference Frame is available for motion estimation. In Dual Frame motion compensation, one short-term reference Frame and one long-term reference Frame are available for prediction. In this paper, we propose a Dual Frame motion compensation technique that allocates bits unevenly among Frames to periodically create a high-quality Frame that serves as the long-term reference Frame for some time. By modifying an MPEG-4 encoder to use this technique on a set of video sequences, we show that it outperforms a normal Dual Frame motion compensation scheme in which the long-term reference Frames are regular Frames that are not allocated any extra rate.
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Dual Frame motion compensation for a rate switching network - eScholarship
2003Co-Authors: Chellappa, P.c. Cosman, Geoffrey M. VoelkerAbstract:Dual Frame motion compensation for a rate switching network Vijay Chellappa, Pamela C. Cosman and Geoffrey M. Voelker Dept. of Electrical and Computer Engineering, Dept. of Computer Science and Engineering University of California, San Diego La Jolla, CA 92093-0407 Email: {vchellap, pcosman}@ucsd.edu,voelker@cs.ucsd.edu Abstract-Standard video coders often use the im- mediate past Frame as a reference Frame with motion compensation for video encoding. In this paper, we use Dual reference Frame motion compensation in the context of high bandwidth to low bandwidth switching such as from an Ethernet connection to a GPRS system. The implementation is based on MPEG-4. Simulation results show that there is a significant gain in the PSNR for relatively static video sequences. Wireless Access Network WLAN Ethernet I Bandwidth I IlMbps - IGbps IOMbps 500kbps IxRTT GPRS 64kbDs ldkbps TABLE I NETWORKS SUPPORTED BY T H E ABC F R A M E W O R K I. INTRODUCTION Standard video coders use temporal coding with motion compensation to achieve compression gains. This is based on the assumption that the past Frame is highly correlated with the current Frame. We propose to use Dual Frame motion compensation in wireless network settings that experience significant transi- tions in network capacity, such as those produced by network handoffs while using services such as Always Best Connected (ABC) [I]. B. Duuljkme motion compensation In multiple Frame prediction, the encoder uses more than one reference Frame for motion compen- sated prediction. A Dual Frame encoder is a special case of a multiple Frame encoder, in which two Frames are used for motion compensation; they are often called the short-term past Frame and the long- term past Frame. The idea of using a long-term past Frame as an additional reference Frame for motion compensation was considered in several papers [2], [3], [4], [SI as well as in the recent H.264 standard. [2] is one of the earliest papers to employ multiple Frames for motion compensation to reduce the number of bits required to code the difference signal. Substantial coding gains were reported. In [3], a multi-Frame extension was proposed to the single Frame reference temporal coding. This was shown to yield improved com- pression efficiency because of the extended search provided by additional Frames for Block Motion Compensation, It was further shown that this multi- Frame extension was robust to wireless channel losses, where the channel was modelled as a multi- state Markov chain. Error resilience was obtained by randomly choosing among the stored Frames A. The ABC network With the widespread use of wireless access net- works and the deployment of 3G services, connec- tivity service to the Internet with mobile devices such as PDAs and laptops needs to be maintained. The ABC service assists the user by automatically handling selection of access networks based on net- work availability and user preferences. Table I shows the various access networks supported by the ABC service. The ABC network provides the Framework for a user who wants to connect to a service to be able to choose network access and devices in a way that best suits his or her needs, and to change networks when something better becomes available. 0-7803-8104-1/03/$17.00 02003 IEEE
P.c. Cosman - One of the best experts on this subject based on the ideXlab platform.
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Dual Frame video coding with pulsed quality and a lookahead window
Data Compression Conference (DCC'06), 2006Co-Authors: M. Tiwari, P.c. CosmanAbstract:In Dual Frame video coding, one short-term reference Frame and one long-term reference Frame are available for motion compensation. In prior research, it was shown that overall video quality was improved by allocating bits unevenly among Frames so as to periodically create a high-quality Frame that could serve as the long-term reference Frame for some time. We extend this work to a cognitive radio scenario where pulses of extra bandwidth can be rented by the second, but rental agreements can be cancelled on short notice if the legacy user of that spectrum returns. With a scalable video coder, this pulse of extra bandwidth can be used to improve the quality of the current Frame being encoded, or of the past long term Frame, or can be spent on future Frames if the encoder has access to them in advance. We compare these various uses to explore the advantages of allocating some of the available bandwidth to past or future Frames
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Optimal mode selection for a pulsed-quality Dual-Frame video coder
IEEE Signal Processing Letters, 2004Co-Authors: A. Leontaris, Vijay Chellappa, P.c. CosmanAbstract:A Dual-Frame video coder employs two past reference Frames for motion compensated prediction. Compared to conventional single Frame prediction, the Dual-Frame encoder can have advantages both in distortion-rate performance and in error resilience. In previous work, it was shown that optimal mode selection can enhance the performance of a Dual-Frame encoder. In another strand of previous work, it was shown that uneven assignment of quality to Frames, to create high-quality (HQ) long-term reference Frames, can enhance the performance of a Dual-Frame encoder. In this letter, we combine these two strands and demonstrate the performance advantages of optimal mode selection among HQ Frames for video transmission over noisy channels.
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Dual Frame motion compensation for a rate switching network - eScholarship
2003Co-Authors: Chellappa, P.c. Cosman, Geoffrey M. VoelkerAbstract:Dual Frame motion compensation for a rate switching network Vijay Chellappa, Pamela C. Cosman and Geoffrey M. Voelker Dept. of Electrical and Computer Engineering, Dept. of Computer Science and Engineering University of California, San Diego La Jolla, CA 92093-0407 Email: {vchellap, pcosman}@ucsd.edu,voelker@cs.ucsd.edu Abstract-Standard video coders often use the im- mediate past Frame as a reference Frame with motion compensation for video encoding. In this paper, we use Dual reference Frame motion compensation in the context of high bandwidth to low bandwidth switching such as from an Ethernet connection to a GPRS system. The implementation is based on MPEG-4. Simulation results show that there is a significant gain in the PSNR for relatively static video sequences. Wireless Access Network WLAN Ethernet I Bandwidth I IlMbps - IGbps IOMbps 500kbps IxRTT GPRS 64kbDs ldkbps TABLE I NETWORKS SUPPORTED BY T H E ABC F R A M E W O R K I. INTRODUCTION Standard video coders use temporal coding with motion compensation to achieve compression gains. This is based on the assumption that the past Frame is highly correlated with the current Frame. We propose to use Dual Frame motion compensation in wireless network settings that experience significant transi- tions in network capacity, such as those produced by network handoffs while using services such as Always Best Connected (ABC) [I]. B. Duuljkme motion compensation In multiple Frame prediction, the encoder uses more than one reference Frame for motion compen- sated prediction. A Dual Frame encoder is a special case of a multiple Frame encoder, in which two Frames are used for motion compensation; they are often called the short-term past Frame and the long- term past Frame. The idea of using a long-term past Frame as an additional reference Frame for motion compensation was considered in several papers [2], [3], [4], [SI as well as in the recent H.264 standard. [2] is one of the earliest papers to employ multiple Frames for motion compensation to reduce the number of bits required to code the difference signal. Substantial coding gains were reported. In [3], a multi-Frame extension was proposed to the single Frame reference temporal coding. This was shown to yield improved com- pression efficiency because of the extended search provided by additional Frames for Block Motion Compensation, It was further shown that this multi- Frame extension was robust to wireless channel losses, where the channel was modelled as a multi- state Markov chain. Error resilience was obtained by randomly choosing among the stored Frames A. The ABC network With the widespread use of wireless access net- works and the deployment of 3G services, connec- tivity service to the Internet with mobile devices such as PDAs and laptops needs to be maintained. The ABC service assists the user by automatically handling selection of access networks based on net- work availability and user preferences. Table I shows the various access networks supported by the ABC service. The ABC network provides the Framework for a user who wants to connect to a service to be able to choose network access and devices in a way that best suits his or her needs, and to change networks when something better becomes available. 0-7803-8104-1/03/$17.00 02003 IEEE
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Video compression with intra/inter mode switching and a Dual Frame buffer
Data Compression Conference 2003. Proceedings. DCC 2003, 2003Co-Authors: A. Leontaris, P.c. CosmanAbstract:Video codecs that use motion compensation have achieved performance improvements from the use of intra/inter mode switching decisions within a rate-distortion Framework. A separate development has involved the use of multiple Frame prediction, in which more than one past reference Frame is available for motion estimation. It is shown that using a Dual Frame buffer, together with intra/inter mode switching improves the compression performance of the coder. Also, the mode switching algorithm is improved with the use of half-pel motion vectors.
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Dual Frame video encoding with feedback
The Thrity-Seventh Asilomar Conference on Signals Systems & Computers 2003, 2003Co-Authors: A. Leontaris, P.c. CosmanAbstract:A special case of multiple Frame prediction is the Dual Frame buffer, where an encoder uses both an immediate past Frame and a long term past Frame for motion compensation. Using a Dual Frame buffer together with intra/inter mode switching improves the compression performance of the coder. In this work, we investigate the effect of feedback in making better mode-switching decisions in the context of rate-distortion optimization. Feedback information is used to limit drift errors due to packet losses by synchronizing the long-term Frame buffers of the encoder and decoder, and refining the input to the mode-switching decision mechanism. Experimental results show an improvement in PSNR of up to 1.6 dB.
