3D Video Coding for Embedded Devices by Bruno Zatt Muhammad Shafique Sergio Bampi & Jörg Henkel

Author:Bruno Zatt, Muhammad Shafique, Sergio Bampi & Jörg Henkel
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

The bitrate relations associated with prediction hierarchy, however, are not always true and vary with the video/image properties of each view. For instance, in the example provided in Fig. 4.10, View 6 (P-View) presents reduced bitrate in relation to View 1 and View 3 (both B-Views). Thus, we may conclude that even employing bi-prediction at disparity domain the Views 1 and 3 are harder to predict in relation to View 6 and produce higher bitrate. Similar observation is the increased bitrate generated by View 7 if compared to other P-Views. Reduced bitrate is expected, but for View 7 an increased bitrate is measured. These observations show that besides the relation to the prediction structure (as discussed above), the bitrate distribution has a high dependence on the video content of each view. Hard-to-predict views typically present high texture and/or high motion/disparity objects and require more bits to reach a given video quality.

The bitrate distribution at frame level presented in Fig. 4.11 shows that inside each GOP the frames that present higher bitrate are located at lower hierarchical prediction levels. This is related to the distance of temporal references; the farther the reference the more difficult is to find a good prediction. Therefore, more error is inserted resulting in higher bitrates. In B-Views this effect is attenuated once this view is less dependent on temporal references due to the higher availability of disparity references. Figure 4.11 illustrates that for neighboring GGOPs the frames at same relative position exhibit similar and periodic rate distribution pattern, the GOP-Phase.

Fig. 4.11Frame-level bitrate distribution for two GGOPs (Flamenco2, QP = 32)

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