Characterization and modelling of MPEG video source
1996
Hochschulschrift
Zugriff:
84
In order to gain an insight into the characteristics of bit- rate variation, we characterize and model a whole length MPEG bit-rate sequence in the thesis. We propose a model to grasp the long-term and short-term correlations of bit-rate variation. As there are I, P, and B types of frames in an MPEG video sequence, our model is composed of three subsequences. The subsequences are self-similar, each with long-range dependence in itself and short-range dependence with each other. In looking for the bit-rate distriution, we find that for P- and B-frames, the whole picture sequence and the `group of pic- tures' (GOP) sequence, a PT5 density function fits the distribu- tion better than the frequently used gamma density function in the literature. The latter is suitable for I- frames, however. In analyzing the sample autocovariances, we point out the long-range dependence (LRD) and self-similarities in an MPEG source and use various methods to estimate the Hurst parameter. In addition, from the perspective of coding algorithm, we point out the non-stationarity in an MPEG sequence and propose appro- priate calculations of time- averaged sample autocovariances, wherein the separate means of I-, P- and B-frames are taking into account. In the generation of synthetic MPEG sequences, a "two-layer" synthesis approachis adopted. The time-averaged autocovariances are modeled by a Gaussian sequence, and the marginal distribut- ions of separate frame types are modeled by transforming the Gaussian sequence into the corresponding density functions. Via the transformation, the non-stationarity of the model is simul- taneously restored. From the statistical results, the model be- haves well in modeling histograms and LRD, but slightly looses its accuracy in matching autocovariances at large lags.
Titel: |
Characterization and modelling of MPEG video source
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Autor/in / Beteiligte Person: | Chang,Wei-Hsang ; 張維顯 |
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Veröffentlichung: | 1996 |
Medientyp: | Hochschulschrift |
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