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The objective of this work is to investigate the performance of a new inloop filter for video compression, which uses temporal rather than spatial information to improve the quality of reference frames used for prediction. The new filter has been integrated into the H.264/AVC baseline encoder and tested on a wide range of sequences. Experimental results show that the filter achieves a bit rate reduction...
Depending on the content of a video sequence and the settings used for encoding it, the amount of bits spent for the transmission of motion vector information can be enormous and in some cases even take the largest fraction of the bit rate. This is not always necessary since often wide areas, i.e. background or large foreground regions, fit the same global motion. Additionally, a global motion model...
Sprite coding, as standardized in MPEG-4 Visual, can result in superior performance compared to common hybrid video codecs both objectively and subjectively. However, state-of-the-art video coding standard H.264/AVC clearly outperforms MPEG-4 Visual sprite coding in broad bit rate ranges. Based on the sprite coding idea, this paper proposes a video coding technique that merges the advantages of H...
Several algorithms for global motion estimation in video sequences using pixel- or block-based approaches have been published. Most known pixel-based methods lack in performance while when using block-based algorithms working on motion vectors, robustness to outliers and accuracy is missing. In this paper we present the fundamentals of a significantly improved, robust block-based method for global...
Techniques for modeling the background of a video sequence can be useful in alternative video coding approaches. Sprite coding has been evolved to provide high quality decoded video frames after transmission by a reduced amount of bits. However, it has also been shown that this works only for a certain kind of video sequences. It also meets quality limits due to the Sprite generation step. To tackle...
Recent deblocking techniques are based on spatial filtering. We present a new deblocking technique based on temporal filtering of spatially aligned frames. This approach is used in an H.264/AVC coding environment. The algorithm estimates the ideal amount of frames used for temporal filtering at the encoder side. In that way it is assured that the receiver is presented with the best possible visual...
Sprite-based video coding offers higher compression efficiency than conventional block-based hybrid video coders. In sprite coding a sequence is divided into a model of its background, i.e. a so-called background sprite image, and a foreground object sequence. These are then encoded and transmitted to the receiver. At the decoder the output video sequence is synthesized using content previously transmitted...
Global motion is estimated either in the pixel domain or in block based domain. Until now, all the approaches regarding the latter are based on fixed sized blocks while the recent compression methods tend to use variable block sizes during motion estimation. In this paper we present a new procedure for global motion estimation based on a variable block size motion vector field. A block matching algorithm...
Pixel-based and motion vector-based global motion estimation (GME) techniques are evaluated in this paper with an automatic system for camera motion characterization. First, the GME techniques are compared with a frame-by-frame PNSR measurement using five video sequences. The best motion vector-based GME method is then evaluated together with a common and a simplified pixel-based GME technique for...
It is well known that video material with a static background allows easier segmentation than that with a moving background. One approach to segmentation of sequences with a moving background is to use preprocessing to create a static background, after which conventional background subtraction techniques can be used for segmenting foreground objects. It has been recently shown that global motion estimation...
The latest standardized hybrid video codec, H.264/AVC, significantly outperforms earlier video coding standards. Despite combining improved and new algorithms within this codec, it is still possible to find methods which lead to a higher coding efficiency. We tackle the prediction problem adding a new prediction mode to the codec. It has been shown that the generation of a background sprite image...
The composition of panoramic images has recently received considerable attention. While panoramic images were first used mainly as a flexible visualization technique, they also found application in video coding, video enhancement, format conversion, and content analysis. The topic has enlarged and diverged into many specialized research directions, which makes it difficult to stay in touch with recent...
In recent years advanced video codecs have been developed, such as standardized in MPEG-4. The latest video codec H.264/AVC provides compression performance superior to previous standards, but is based on the same basic motion-compensated-DCT architecture. However, for certain types of video, it has been shown that it is possible to outperform the H.264/AVC using an object-based video codec. Towards...
Recent work has shown that object-based video coding can provide higher coding gain than common H.264/AVC for single-view and the MVC standard based on H.264 for multi-view (MVC). The use of background sprites outperformes the AVC/MVC especially in sequences containing rotating camera motion and moving foreground objects. The coding performance strongly relies on the preprocessing steps, e.g. sprite...
Object-based video coding, as standardized in MPEG-4 Part 2, can result in superior performance in comparison to common hybrid motion-compensated DCT-based approaches. We consider sprite coding which increases significantly the objective as well as the subjective quality of the coded video. The main challenge of this approach is the pre-segmentation of the video and the video content itself. To apply...
Many algorithms have been developed to recognize regions, edges, color, and objects in images and videos. For applications like surveillance or object-based video coding, it is important to segment the foreground objects from the background. The task is very challenging in the case of a moving camera. We present a foreground segmentation approach that is designed for sprite coding as well as other...
Work is currently underway to develop a new multi-view video coding (MVC) standard, based on the recent H.264/AVC standard. Recent work has shown, however, that object-based video coding can provide higher performance than H.264, especially at low bit rates and in sequences containing rotating camera motion and moving objects in the foreground. In this paper, we propose an object-based extension to...
We consider the warping problem which appears in well-known image registration algorithms that use higher-order motion models. An implementation inspired by recent work and a new image registration algorithm are used for the analysis. Both approaches rely on frame-to-frame estimation. The key technique is the well-established gradient descent approach for the estimation of higher-order motion parameters...
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