# A Framework for Symmetric-Quality S3D Video Streaming Services
## 3 Proposed Solution  
As previously mentioned, due to the differences in resolution or quality between the left and right videos, viewers may experience discomfort when watching 3D content. To address this issue of asymmetry and ensure symmetrical quality between the left and right videos, it was necessary to generate a high-resolution right-view video. To overcome this challenge, we propose a new encoding framework that combines the conditional replenishment algorithm with Cross-View SHVC. This framework is designed using the non-HEVC option of the SHVC encoder, which is a key factor for maximizing efficiency in hierarchical video coding. The non-HEVC option of the SHVC encoder reuses an already encoded base layer image and utilizes it as an inter-layer prediction signal to generate the enhancement layer stream. This method eliminates the need to re-encode the base layer, allowing the enhancement layer to be generated based on the already encoded base layer data, thereby reducing encoding complexity and improving efficiency. Additionally, it provides the advantage of delivering high-quality video while conserving bandwidth. The Cross-View SHVC shown in Figure 4 is designed with a structure that uses the decoded video as the base layer for inter-layer prediction signals. In other words, the base layer, consisting of the down-sampled version of the right-view video, is used as a prediction signal when generating the enhancement layer. However, the conventional Cross-View SHVC method has limitations, as it does not fully resolve the quality differences between the left and right videos. Therefore, the proposed method introduces a more advanced approach rather than strictly adhering to the existing structure. Specifically, while the base layer of the left-view video is retained, the base layer of the right-view video uses a high-quality image restored using the conditional replenishment algorithm. By applying this high-quality image to the base layer of the right-view video, a better-quality prediction signal is provided during enhancement layer encoding. This approach generates a higher-quality right-view video compared with the conventional method, which uses only the decoded base layer image, effectively addressing the asymmetry between the left and right videos. Figure 9 illustrates the overall flow of the proposed encoding framework, which includes step-by-step processes designed to ensure symmetrical quality between the left and right videos and achieve efficient 3D video encoding. In the first step, the right-view video in HD resolution is encoded using the HEVC codec. This process generates the right-view base layer stream and an HEVC-encoded right-view video. This step provides a low-resolution base layer stream, which can be used for playback on mobile devices and similar environments. In the second step, the UHD resolution left-view video is input into the Cross-View SHVC encoder, where it is processed using the non-HEVC option. This process generates the left-view video enhancement layer stream and the left-view video. Cross-View SHVC leverages the correlation between the left and right views to improve encoding efficiency and plays a crucial role in enhancing the quality of the left-view video. Figure 9: Proposed encoding framework schematic diagram. The third step applies VEI (Video Enhancement Information) encoding, specifically the conditional replenishment algorithm. In this step, the HEVC-encoded right-view video, the Cross-View SHVC-encoded left-view video, and the original right-view video are used as inputs to the VEI encoding process. This generates a VEI-applied right-view video, which restores low-resolution blocks in the right-view video and significantly improves the overall quality. Through this process, the asymmetry in video quality is resolved, and an enhanced video quality is provided. In the final step, the VEI-applied right-view video is used as the base layer, and the original right-view video is re-encoded using Cross-View SHVC.