## 2 Scalable Video Coding (SVC) an Extension to H.264/Advanced Video Coding (AVC)  
The layered video coding techniques enable the video adaptation. The H.26x series of video compression techniques is popular and mostly used currently. In this series, H.264/AVC [5] is most commonly used, and the majority of the video communication applications use it to encode and decode. The H.265/HEVC (High-Efficiency Video Coding) [10] is the latest compression that is available, but the application that uses this compression technique is limited. Recently, an international committee was formed to develop a new compression method called H.266/VVC (Versatile Video Coding) [11]. In this experiment, we considered Scalable Video Coding (SVC) an extension to H.264/AVC [6], as streaming and adaptation using SVC encoding is still a major research challenge that needs to be addressed. Adaptation is a method that can be used with any layered encoders. SVC supports scalability in terms of spatial, temporal, and quality resolutions. Spatial scalability represents variations of the spatial resolution with respect to the original picture. The temporal scalability describes subsets of the bit-stream, which represent the source content with a varied frame rate. Quality scalability is also commonly referred to as fidelity or Signal-to-Noise Ratio (SNR) scalability. In Scalable Video Coding, one base layer and multiple enhancement layers are generated. The base layer is the independent layer, and each enhancement layer is coded keeping previous layers as a reference layer. As a result, it generates a single bit-stream and enables the removal of partial bit-stream in such a way that it forms a valid bit-stream, as shown in Figure 1. The base layer consumes more bandwidth compared to the enhancement layer. Consequently, effective bandwidth consumption is much less. The increase in efficiency comes at the expense of some increase in complexity as compared to simulcast coding. In simulcast, multiple video sequences are generated to meet the different resolution and frame rates. The SVC standard enhances the temporal prediction feature of AVC. Here, instead of a single-layer coding, multi-layer method is followed. The major difference between AVC and SVC in terms of temporal scalability is signaling the temporal layer information. The hierarchical prediction concept is being used in SVC. The dyadic hierarchical prediction has more coding efficiency than that of other prediction structures, like a non-dyadic and no-delay prediction. The spatial layer represents the spatial resolution, and the dependency identifier used for it is D. The base layer is equated to level 0 and the level is increased for each enhanced layer. In each spatial layer, motion-compensated prediction and intra-prediction are employed for single-layer coding. In simulcast, the same video will be coded with different spatial resolution, but, in spatial dependency, inter-layer prediction mechanisms are incorporated to improve the coding efficiency. The inter-layer prediction includes techniques for motion parameter and residual prediction, and the temporal prediction structures of the spatial layers should be temporally aligned for efficient use of the inter-layer prediction. For Quality or SNR scalability, coarse-grain SNR scalability (CGS) and medium grain SNR scalability (MGS) are distinguished in scalable video coding. The Quality scalable layer is identified by Q, where each spatial layer will have many quality layers. The decoder selects the Q value based on the requirement and decodes the quality for each spatially enhanced frame. The SVC encoder combines all the above-mentioned scalability to code a video sequence as shown in Figure 2. The original video sequence is initially down-sampled up to the minimum resolution expected in video communication. Later, the base layer is coded independently. By keeping the base layer and spatial levels as a reference, enhancement layers are generated. The number of the enhancement layer is decided by the temporal levels.