otoniel lopez - Academia.edu (original) (raw)
Papers by otoniel lopez
Distributed Video Coding (DVC) is a promising coding solution for some emerging applications, whe... more Distributed Video Coding (DVC) is a promising coding solution for some emerging applications, where the encoder complexity, power consumption or memory requirements are constraint the system resources. Current approaches to DVC focus on improving the performance of the Wyner-Ziv coding by improving the quality of the reconstructed side information or by improving the quality of channel codes. Up to date, no attention has been paid to the problem of key frames coding where a low-encoding complexity scenario is also needed. This work focuses on key frames coding in its effect to the Wyner-Ziv frames decoding aiming to implement a very low-complexity Turbo Trellis Coded Modulation (TTCM) based DVC architecture. In this paper, we propose a new key frame coding scheme which has very low complexity and memory requirements for the TTCM based distributed video codec. Results show that the proposed intra frame codec for key frame coding outperforms the JPEG2000 and the Intra H.264 AVC codecs in terms of encoding-time and memory requirements, with better RD performance.
The 3D-DWT is a mathematical tool of increasing importance in those applications that require an ... more The 3D-DWT is a mathematical tool of increasing importance in those applications that require an efficient processing of volumetric info. Other applications like professional video editing, IPTV video surveillance applications, live event IPTV broadcast, multi-spectral satellite imaging, HQ video delivery, etc, would rather use 3D-DWT encoders to reconstruct a frame as fast as possible. However, the huge memory requirement of the algorithms that compute the 3D-DWT is one of the main drawbacks in practical implementations. In this paper, we introduce a fast frame-based 3D-DWT video encoder with low memory usage. In addition, there is no need to divide the input video sequence into group of pictures (GOP), and it can be applied in a continuous manner, so that no boundary effects between GOPs appear.
Intra video coding is a common way to process video material for applications like professional v... more Intra video coding is a common way to process video material for applications like professional video editing systems, digital cinema, video surveillance applications, multispectral satellite imaging, HQ video delivery, etc. Most practical intra coding systems employ JPEG encoders due to their simplicity, low coding delay and low memory requirements. JPEG2000 is the main candidate to replace JPEG in this kind of applications due to the excellent R/D performance and high coding flexibility. However, its complexity and computational resources required for proper operation could be a limitation for certain applications. In this work, we propose an intra video codec, M-LTW, which is able to reach very good R/D performance results, as well as JPEG2000 or H.264 INTRA, with faster processing and lower memory usage.
Signal Processing-image Communication, 2008
Compression of wavelet coefficient sign has been assumed to be inefficient for a long time. Howev... more Compression of wavelet coefficient sign has been assumed to be inefficient for a long time. However, in the last years several proposals have been developed and, in fact several image encoders like JPEG 2000 include sign coding capabilities. In this paper, we present a new sign coding approximation using a genetic algorithm in order to efficiently predict the sign of wavelet coefficients. We have included that prediction in a fast non-embedded image encoder. Preliminary results show that, by including sign coding capabilities to a non-embedded encoder, the compression gain is up to 17.35%, being the Rate-Distortion (R/D) performance improvement up to 0.25 dB.
The 3D-DWT is a mathematical tool of increasing importance in those applications that require an ... more The 3D-DWT is a mathematical tool of increasing importance in those applications that require an efficient processing of volumetric info. However, the huge memory requirement of the algorithms that compute it is one of the main drawbacks in practical implementations. In this paper, we introduce a fast frame-based 3D-DWT video encoder with low memory usage, based on lower-trees. In this scheme, there is no need to divide the input video sequence into group of pictures (GOP), and it can be applied in a continuous manner, so that no boundary effects between GOPs appear.
Delivery of video encoded bitstreams in wireless networks is a challenging task due to different ... more Delivery of video encoded bitstreams in wireless networks is a challenging task due to different factors (node mobility, time-varying wireless channel, etc.) that put in evidence the lack of QoS support for this kind of applications. In particular, we are working with teleoperated mobile robot systems. Our purpose is to perform a study about the behavior of IEEE 802.11 technology to evaluate if it would be able to comply with the requirements of this application. So, we have developed a prototype that consists of one mobile robot with an onboard webcam and an IEEE 802.11 network adapter. The control station sends navigation commands to the robot and, at the same time, receives a video stream that shows to the user a frontal view of actual robot location. We will analyze the different components of the overall system, making special emphasis in video coding engines and network response.
Most recently developed wavelet image emcoders support as native feature an embedded bitrate cont... more Most recently developed wavelet image emcoders support as native feature an embedded bitrate control that could be useful for applications where obtaining an accurate bitrate is critical. Well-known encoders like JPEG2000 and SPIHT employ embedded coding. However, this feature makes them highly complex, being a serious restriction for certain applications and devices (such as mobile multimedia communications involving PDAs, mobile phones, etc.). As a consequence, in the last years, authors proposed non-embedded encoders with vetyfast and low-memory-demanding encoding/decoding processes. In this paper, we propose rate control tools that are able to supply the required rate control accuracy with as low as possible complexity increase. Experimental tests show that good results are obtained by employing trivial models of the encoder engine, being able to modulate the accuracy degree with lightweight iterative versions
Signal Processing-image Communication, 2008
Distributed Video Coding (DVC) is a promising coding solution for some emerging applications, whe... more Distributed Video Coding (DVC) is a promising coding solution for some emerging applications, where the encoder complexity, power consumption or memory requirements are constraint the system resources. Current approaches to DVC focus on improving the performance of the Wyner-Ziv coding by improving the quality of the reconstructed side information or by improving the quality of channel codes. Up to date, no attention has been paid to the problem of key frames coding where a low-encoding complexity scenario is also needed. This work focuses on key frames coding in its effect to the Wyner-Ziv frames decoding aiming to implement a very low-complexity Turbo Trellis Coded Modulation (TTCM) based DVC architecture. In this paper, we propose a new key frame coding scheme which has very low complexity and memory requirements for the TTCM based distributed video codec. Results show that the proposed intra frame codec for key frame coding outperforms the JPEG2000 and the Intra H.264 AVC codecs in terms of encoding-time and memory requirements, with better RD performance.
The 3D-DWT is a mathematical tool of increasing importance in those applications that require an ... more The 3D-DWT is a mathematical tool of increasing importance in those applications that require an efficient processing of volumetric info. Other applications like professional video editing, IPTV video surveillance applications, live event IPTV broadcast, multi-spectral satellite imaging, HQ video delivery, etc, would rather use 3D-DWT encoders to reconstruct a frame as fast as possible. However, the huge memory requirement of the algorithms that compute the 3D-DWT is one of the main drawbacks in practical implementations. In this paper, we introduce a fast frame-based 3D-DWT video encoder with low memory usage. In addition, there is no need to divide the input video sequence into group of pictures (GOP), and it can be applied in a continuous manner, so that no boundary effects between GOPs appear.
Intra video coding is a common way to process video material for applications like professional v... more Intra video coding is a common way to process video material for applications like professional video editing systems, digital cinema, video surveillance applications, multispectral satellite imaging, HQ video delivery, etc. Most practical intra coding systems employ JPEG encoders due to their simplicity, low coding delay and low memory requirements. JPEG2000 is the main candidate to replace JPEG in this kind of applications due to the excellent R/D performance and high coding flexibility. However, its complexity and computational resources required for proper operation could be a limitation for certain applications. In this work, we propose an intra video codec, M-LTW, which is able to reach very good R/D performance results, as well as JPEG2000 or H.264 INTRA, with faster processing and lower memory usage.
Signal Processing-image Communication, 2008
Compression of wavelet coefficient sign has been assumed to be inefficient for a long time. Howev... more Compression of wavelet coefficient sign has been assumed to be inefficient for a long time. However, in the last years several proposals have been developed and, in fact several image encoders like JPEG 2000 include sign coding capabilities. In this paper, we present a new sign coding approximation using a genetic algorithm in order to efficiently predict the sign of wavelet coefficients. We have included that prediction in a fast non-embedded image encoder. Preliminary results show that, by including sign coding capabilities to a non-embedded encoder, the compression gain is up to 17.35%, being the Rate-Distortion (R/D) performance improvement up to 0.25 dB.
The 3D-DWT is a mathematical tool of increasing importance in those applications that require an ... more The 3D-DWT is a mathematical tool of increasing importance in those applications that require an efficient processing of volumetric info. However, the huge memory requirement of the algorithms that compute it is one of the main drawbacks in practical implementations. In this paper, we introduce a fast frame-based 3D-DWT video encoder with low memory usage, based on lower-trees. In this scheme, there is no need to divide the input video sequence into group of pictures (GOP), and it can be applied in a continuous manner, so that no boundary effects between GOPs appear.
Delivery of video encoded bitstreams in wireless networks is a challenging task due to different ... more Delivery of video encoded bitstreams in wireless networks is a challenging task due to different factors (node mobility, time-varying wireless channel, etc.) that put in evidence the lack of QoS support for this kind of applications. In particular, we are working with teleoperated mobile robot systems. Our purpose is to perform a study about the behavior of IEEE 802.11 technology to evaluate if it would be able to comply with the requirements of this application. So, we have developed a prototype that consists of one mobile robot with an onboard webcam and an IEEE 802.11 network adapter. The control station sends navigation commands to the robot and, at the same time, receives a video stream that shows to the user a frontal view of actual robot location. We will analyze the different components of the overall system, making special emphasis in video coding engines and network response.
Most recently developed wavelet image emcoders support as native feature an embedded bitrate cont... more Most recently developed wavelet image emcoders support as native feature an embedded bitrate control that could be useful for applications where obtaining an accurate bitrate is critical. Well-known encoders like JPEG2000 and SPIHT employ embedded coding. However, this feature makes them highly complex, being a serious restriction for certain applications and devices (such as mobile multimedia communications involving PDAs, mobile phones, etc.). As a consequence, in the last years, authors proposed non-embedded encoders with vetyfast and low-memory-demanding encoding/decoding processes. In this paper, we propose rate control tools that are able to supply the required rate control accuracy with as low as possible complexity increase. Experimental tests show that good results are obtained by employing trivial models of the encoder engine, being able to modulate the accuracy degree with lightweight iterative versions
Signal Processing-image Communication, 2008