EECE 541 Multimedia Systems Project Proposal: Logo ... - Courses

More documents

Recommendations

Info

Figure 6. Logo insertion in transform domain. D. Low Cost and Efficient Logo Insertion High accuracy and efficiency are two important criteria for logo insertion. One efficient logo-insertion method proposed by Shu Xiao, etc, is shown in [5]. In this paper, the authors presented efficient logo insertion methods for transparent and non-transparent logos for MPEG2 compressed video. They considered the refinement of prediction modes and motion vectors for different types of macroblocks. The method should be able to apply in both spatial and transform domains. In logo-insertion transcoding for MPEG2 compressed video, we need to compensate the changes caused by the logo insertion. Such changes propagate through frames when P and B frames refer to the reference frames in motion prediction process. For H.264 compressed video, however, change propagation happens also for I frames due to the use of intra prediction as described in Section III. Sometimes, logos are not inserted in all frames of a video sequence. Now, we start to introduce the method used in [5] for determining the affected range of frames caused by logo insertion for MPEG2 coded video. D.1. Logo-Affected Range of Frames in the Temporal Domain Let [l, h] denote the range of the video sequence where a logo is required to be inserted. That is, the indices l and h are the lowest and highest frame numbers of this range, respectively. We further let [L, H] represent the range of video sequence which is affected by the logo insertion due to the change propagation caused by frame reference. Clearly, we have [l, h] being a subset of [L, H]. Reference frames are frames of a 10
compressed video that are used to define future frames. In MPEG2 video coding standard, reference frames are I and P frames. The previous reference frame lr and next reference frame hr of the range [l, h] are defined to be the reference frames outside the range [l, h] with the largest and smallest frame numbers, respectively. Then, the indices L and H can be determined using (3) and (4), as follows: L = lr + 1, (3) ⎧ hr if hr is not I frame, H = ⎨ (4) ⎩hr −1 otherwise. Figure 7 gives two examples of logo-affected range of frames. In this example, we use the typical group of picture (GOP) structure: IBBPBBPBBP…, where I and P frames are reference frames. The frame dependencies are also drawn in the figure. In the logo range example one, [5, 16] is the range of frames [l, h] where logos are added. The previous reference frame lr of the range [l, h] is 3, and the next reference frame hr of the range [l, h] is 18. According to (3) and (4), we got the logo-affected range of frames [L, H] as [4, 18]. Similarly, in example two, the range [L, H] is [4, 14]. Figure 7. Examples of logo affected range of frames. Once the logo affected frame range [L, H] is identified, we can focus on compensating the changes induced by logo insertion within this range of frames. The frames outside the range [L, H] are not affected, and therefore remain unchanged. The scheme described above cannot be directly applied to H.264 compressed video. This is because, in H.264 video coding standard, all three types of frames (i.e., I, P, and B frames) can be used as reference frames. Multiple reference frames are also used, which makes determining the range [L, H] more challenging. The affected-frame range for H.264 coded video needs to be wisely adjusted. D.2. Motion Information Adjustment in the Logo and Logo-Affected Parts Having introduced the logo-affected range of frames, we now state the motion information adjustment in [5]. As mentioned earlier in Section II, a frame can be partitioned into the logo part, logo affected part, and logo unrelated part. For simplicity, in [5], the authors assume that the logo is rectangular and covers integer number of macroblocks. The coding modes and motion vectors for macroblocks at the logo unrelated part shall remain unchanged. In what follows, we discuss the motion-vector refinement of macroblocks in the logo and logo-affected parts, respectively. 11
Page 1 and 2: EECE 541 Multimedia Systems Project
Page 3 and 4: I. INTRODUCTION Transcoding is the
Page 5 and 6: Figure 2. Open-loop architecture. O
Page 7 and 8: may contain a significant amount of
Page 9: In [4], it shares the same architec
Page 13 and 14: E.1. Constant Quality at the Logo P
Page 15 and 16: not to be changed. In other words a

EECE 541 Multimedia Systems Project Proposal: Logo ... - Courses

Create successful ePaper yourself

Delete template?

Save as template?