In the adaptive intra refresh method adopted in MPEG-4, a case that errors occurring in transmission propagate frame to frame and also spread inside a frame is still observed. This paper proposes a modified method for...
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In the adaptive intra refresh method adopted in MPEG-4, a case that errors occurring in transmission propagate frame to frame and also spread inside a frame is still observed. This paper proposes a modified method for performing the intra refresh adaptively. This method applies an intra-block encoding scheme to macro-blocks according to the number of pixels referred in the motion compensated predictive coding scheme, instead of applying it to moving macro-blocks just periodically in a fixed order inside the frame. Simulation results using test sequences demonstrate that this method reduces error propagation in shorter term than the conventional method, while causing less increase of the number of codes. The number of error spread pixels decreases by about 30% in the proposal method
Motion information scalability is important for scalable bit-stream adaptation on low bit-rates, when motion rate occupies a significant portion of the total bit-rate. This type of scalability can be achieved by layer...
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Motion information scalability is important for scalable bit-stream adaptation on low bit-rates, when motion rate occupies a significant portion of the total bit-rate. This type of scalability can be achieved by layered representation of motion block partitioning and predictive coding of associated motion vectors across these layers. So far, several approaches for creating layered motion structure targeting quality scalability have been proposed and in this paper their accuracy is evaluated. For that purpose optimal motion models have been found. It has been shown that simple evaluation of reconstruction error at the encoder side improves suboptimal modeling techniques.
Enhanced intra and inter prediction techniques are the key factors to the success of H.264. There are a total of nine optional prediction modes for each 4 times 4 luma block. The choice of intra prediction mode for ea...
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Enhanced intra and inter prediction techniques are the key factors to the success of H.264. There are a total of nine optional prediction modes for each 4 times 4 luma block. The choice of intra prediction mode for each 4 times 4 block must be signalled to the decoder and this could potentially require a large number of bits. However, intra modes for neighbouring 4 times 4 blocks are often correlated. To take advantage of this correlation, predictive coding is used to signal 4 times 4 intra modes. At the boundaries of frame, we can't apply all modes because of limitation of available pixels for prediction. Now question arises, is it feasible to use same technique to signal less number of modes as for nine modes? In this paper we used techniques different than the given technique for nine modes, experimental results show that the proposed methods are more efficient than the existing one
The modified discrete cosine transform (MDCT) is widely used in current perceptual audio coding schemes. This paper presents an integer approximation of this lapped transform, called integer MDCT, which is derived fro...
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The modified discrete cosine transform (MDCT) is widely used in current perceptual audio coding schemes. This paper presents an integer approximation of this lapped transform, called integer MDCT, which is derived from the MDCT using lifting scheme. This reversible integer transform inherits most of the attractive properties of the MDCT, exhibiting a good spectral representation of the audio signal, critical sampling and overlapping, which makes the integer MDCT well suited for both lossless audio coding as well as for combined perceptual and lossless audio coding. A scalable system based on MPEG AAC and integer MDCT is presented providing a lossless enhancement of perceptual audio coding scheme.
The compression efficiency of distributed video-coding (DVC) suffers from the necessity of transmitting a large number of key-frames which are intra-coded. This paper describes a new 3D model-based DVC approach which ...
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The compression efficiency of distributed video-coding (DVC) suffers from the necessity of transmitting a large number of key-frames which are intra-coded. This paper describes a new 3D model-based DVC approach which reduces the key- frame frequency. The decoder first recovers a 3D model from the key-frames. It then predicts the intermediate frames by projecting it onto 2D image planes and applying image-based rendering techniques. This paper also introduces a new quasi-DVC method relying on a limited point tracking at the encoder. It greatly improves the prediction PSNR, while only slightly increasing the encoder complexity. It also allows the encoder to adaptively select the key-frames based on the video motion-content.
Security and QoS are two main issues for a successful wide deployment of multicast services. For instance, in a multicast streaming application, a receiver would require a data origin authentication service as well as...
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Security and QoS are two main issues for a successful wide deployment of multicast services. For instance, in a multicast streaming application, a receiver would require a data origin authentication service as well as a quality adaptation technique for the received stream. Signature propagation and layered multicast are efficient solutions satisfying these two requirements. In this paper we investigate the use of signature propagation to ensure data origin authentication service. We, then, propose a set of novel data origin authentication techniques for layered media-streaming video. In addition to data origin authentication, the proposed techniques offer continuous non-repudiation of the origin and data integrity. These techniques take advantage of the preestablished layered structure of the encoded video data to reduce the overhead and improve the overall verification in lossy network environments. We evaluate the performance of the proposed techniques through extensive simulations using NS2 simulator.
We introduce an efficient algorithm for real-time compression of temporally consistent dynamic 3D meshes. The algorithm uses mesh connectivity to determine the order of compression of vertex locations within a frame. ...
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We introduce an efficient algorithm for real-time compression of temporally consistent dynamic 3D meshes. The algorithm uses mesh connectivity to determine the order of compression of vertex locations within a frame. Compression is performed in a frame to frame fashion using only the last decoded frame and the partly decoded current frame for prediction. Following the predictive coding paradigm, local temporal and local spatial dependencies between vertex locations are exploited. In this framework we present a novel angle preserving predictor and evaluate its performance against other state of the art predictors. It is shown that the proposed algorithm improves up to 25% upon the current state of the art for compression of temporally consistent dynamic 3D meshes.
Image sequence prediction is widely used in image compression and transmission schemes such as differential pulse code modulation (DPCM). In traditional predictive coding, linear predictors are usually adopted to expl...
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Image sequence prediction is widely used in image compression and transmission schemes such as differential pulse code modulation (DPCM). In traditional predictive coding, linear predictors are usually adopted to exploit the inherent redundancy and correlation between neighboring pixels. However, due to the nonstationary and non-Gaussian nature of image sequences, linear predictors are not often very effective. As an alternative, Volterra predictor is able to compensate for the smoothing effects introduced by linear predictor. However, it suffers from noise that may be attributed to quantization errors or image acquisition devices. In this paper, we propose a novel nonlinear polynomial weighted median (PWM) predictor for image sequence prediction. The proposed PWM predictor is more robust to noise, while still retaining the information of higher-order statistics of pixel values. Experimental results illustrate that the PWM predictor yields better results than other predictors especially in noisy case. The proposed scheme can be incorporated in new predictive coding systems.
Summary form only given. In the paper we propose a new adaptive predictor which is based on the blending of multiple static predictors on the dynamically classified causal set of neighboring pixels. The predictor mode...
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Summary form only given. In the paper we propose a new adaptive predictor which is based on the blending of multiple static predictors on the dynamically classified causal set of neighboring pixels. The predictor models the image properties around the current, unknown pixel and adjusts itself to the local image region. The main contribution of this work is the enhancement of the well known approach of predictor blends through highly adaptive determination of blending context on a pixel-by-pixel basis using classification technique. This allows modeling of more complex image structures such as nontrivially oriented edges and the periodicity and coarseness of textures.
We propose a new multi-view video coding method using adaptive selection of motion/disparity compensation based on H.264/AVC. One of the key points of the proposed method is the use of view interpolation as a tool for...
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We propose a new multi-view video coding method using adaptive selection of motion/disparity compensation based on H.264/AVC. One of the key points of the proposed method is the use of view interpolation as a tool for disparity compensation by assigning reference picture indices to interpolated images. Experimental results show that significant gains can be obtained compared to the conventional approach that was often used
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