Αντικείμενο της παρούσας διπλωματικής εργασίας είναι η παρουσίαση και η μελέτη ενος εναλλακτικού σχεδιασμού του deblocking φίλτρου του προτύπου κωδικοποίησης βίντεο Η.264. Αρχικά επεξηγείται αναλυτικά ο τρόπος λειτουργίας του φίλτρου και στη συνέχεια προτείνεται ένας πρωτοποριακός σχεδιασμός με χρήση pipeline πέντε σταδίων. Ο σχεδιασμός παρουσιάζει σημαντικά πλεονεκτήματα στον τομέα της ταχύτητας (ενδεικτικά εμφανίζεται βελτιωμένη απόδοση στην συχνότητα λειτουργίας και στο throughput). Αυτό πιστοποιήθηκε από μετρήσεις που έγιναν σε συγκεκριμένα fpga και επαλήθευσαν τα θεωρητικά συμπεράσματα που είχαν εξαχθεί. / The standard H.264 (or else MPEG-4 part 10) is nowadays the most widely used standard in the area of video coding as it is supported by the largest enterprises in the internet (including Google, Apple and Youtube). Its most important advantage over the previous standards is that it achieves better bitrate without falling in terms of quality.
A crucial part of the standard is the deblocking filter which is applied in each macroblock of a frame so that it reduces the blocking distortion. The filter accounts for about one third of the computational requirements of the standard, something which makes it a really important part of the filtering process.
The current diploma thesis presents an alternative design of the filter which achieves better performance than the existing ones. The design is based in the use of two filters (instead of one used in current technology) and moreover, in the application of a pipelined design in each filter. By using a double filter, exploitation of the independence which exists in many parts of the macroblock is achieved. That is to say, it is feasible that different parts of it can be filtered at the same time without facing any problems. Furthermore, the use of the pipeline technique importantly increases the throughput. Needless to say, in order for the desired result to be achieved, the design has to be made really carefully so that the restrictions imposed by the standard will not be failed. The use of this alternative filter design will result in an important raise in the performance. Amongst all, the operating frequency, the throughput and the quality of the produced video will all appear to be considerably risen. It also needs to be mentioned that the inevitable increase of the area used (because of the fact that two filters are used instead of one) is not really important in terms of cost.
The structure of the thesis is described in this paragraph. In chapter 1 there is a rather synoptic description of the H.264 standard and the exact position of the deblocking filter in the whole design is clarified. After that, the algorithmic description of the filter follows (Chapter 2). In this chapter, all the parameters participating in the filter are presented in full detail as well as the equations used during the process. In the next chapter (chapter 3), the architecture chosen for the design is presented. That is to say, the block diagram is presented and explained, as well as the table of timings which explains completely how the filter works. The pipelining technique applied in the filter is also analyzed and justified in this chapter. In the next chapter (chapter 4), every structural unit used in the current architecture is analyzed completely and its role in the whole structure is presented. Finally, in chapter 5, the results of the measurements made in typical fpgas of Altera and Xilinx are presented. The results are shown in table format whereas for specific parameters diagrams were used so that the improved performance of the current design compared to the older ones that are widely used, becomes evident.
| Identifer | oai:union.ndltd.org:upatras.gr/oai:nemertes:10889/6033 |
| Date | 07 June 2013 |
| Creators | Καβρουλάκης, Νικόλαος |
| Contributors | Θεοδωρίδης, Γεώργιος, Kavroulakis, Nikolaos, Θεοδωρίδης, Γεώργιος |
| Source Sets | University of Patras |
| Language | gr |
| Detected Language | English |
| Type | Thesis |
| Rights | 0 |
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