<title>QCTVA: quality-controlled temporal video adaptation</title>

Abstract

Multimedia streaming is becoming more and more popular. Seamless video streaming in heterogeneous networks like the Internet turns out as almost impossible due to varying network conditions -streams must be adapted to the current network QoS. Temporal scalability is one of the most reasonable adaptation techniques because it is fast and easy to perform. Today's approaches simply drop frames out of a video without spending much effort on finding an intelligent dropping behavior. This usually leads to good adaptation results in terms of bandwidth consumption but also to suboptimal video quality within the given bounds. Our approach offers analysis of video streams to achieve the qualitatively best temporal scalability. For this reason, we introduce a data structure called modification lattice which represents all frame dropping combinations within a sequence of frames. On the basis of the modification lattice, quality estimations on frame sequences can be performed. Moreover, a heuristic for fast and efficient quality computation in a modification lattice is presented. Experimental results illustrate that temporal video adaptation based on QCTVA information leads to a better video quality compared to "usual" frame dropping approaches. Furthermore, QCTVA offers frame priority lists for videos. Based on these priorities, numerous adaptation techniques can increase their overall performance when using QCTVA.

Combining Stream Switching with Fine-Grained Intra-Stream Adaptation for Adaptive Video Streaming

“…The P 1B → P GOP pattern of the streams turned out to be a good compromise. A P 4B → P pattern would offer more adaptation possibilities and would, especially when combined with a quality-based frame prioritization approach like QCTVA [9], also yield slightly better overall PSNR results. Still, timely uniform distribution is simpler and gives reasonable quality results with up to max.…”

Metadata-driven multimedia transcoding for distance learning

“…Transcoding is performed through the MPEG-4 Standard scalable tools [25] in the proposed system to provide temporal, spatial, and Signal-to-Noise Ratio (SNR) scalability (i.e., vary the bit-rate encoding). Recall that the set of rules specified in an XSLT sheet together with the user's UEDT are used to transform the DI metadata.…”

Quality variations of different priority-based temporal video adaptation algorithms

“…Exactly this behavior can be achieved when analyzing the video stream with QCTVA (quality controlled temporal video adaptation) [3]. QCTVA offers the qualitatively best temporal scalability by measuring the visual quality of possible frame dropping combinations based on the well-known PSNR value.…”

“…As the computation of the whole modification lattice is a very time consuming task,;heuristics for best first expansion (BPE) and worst first expansion (WFE) were developed which are discussed in detail in [3]. Figure 1 illustrates a modification lattice which was co�strucled using the BFE heuristic.…”