4.Viewport-Only Equal Quality (Viewport-Dependent)

Viewport-Only Equal Quality (Viewport-Dependent)
仅视口相等质量（取决于视口）

Viewport-Only Equal Quality, often referred to as Viewport-Dependent streaming, is an advancement in 360-degree video streaming that takes into account the viewer’s perspective to allocate higher video quality to the areas within their current field of view. This approach is more bandwidth-efficient compared to Full-View Equal Quality streaming, as it optimizes the quality of the video based on the viewer’s gaze. Here are the key characteristics of this streaming method:

1. Quality Optimization for the Viewed Area: Viewport-Only Equal Quality focuses on providing higher quality to the portion of the 360-degree video that the viewer is currently looking at, which is known as the “viewport.” This prioritizes the viewer’s immediate field of view.

2. Bandwidth Efficiency: By allocating more bits to the viewed area and reducing the quality of non-viewed areas, this method is more bandwidth-efficient compared to Full-View Equal Quality streaming. It conserves network resources and allows for smoother streaming.

3. Dynamic Adaptation: The streaming system continually adapts the encoding based on the viewer’s perspective. As the viewer’s gaze moves within the 360-degree video, the system shifts the higher quality to the new viewport. This dynamic adaptation ensures the best possible quality for the viewer’s current focus.

4. Viewer-Driven Experience: Viewport-Dependent streaming provides a more viewer-driven experience, enhancing immersion and interactivity. The viewer feels like they have control over what they are seeing within the 360-degree environment.

5. Challenges: While more efficient than Full-View Equal Quality, Viewport-Only Equal Quality streaming can still be challenging to implement. It requires real-time tracking of the viewer’s gaze and rapid adjustments in quality allocation as the viewpoint changes.

6. Optimal for Head-Mounted Displays: This streaming method is particularly well-suited for head-mounted displays (HMDs) like virtual reality (VR) headsets, where tracking the viewer’s head movement and gaze is more precise.

Viewport-Only Equal Quality is a significant improvement over the early methods of 360-degree video streaming. It maximizes the quality where it matters most—where the viewer is looking—resulting in a more immersive and efficient viewing experience. As technology and streaming protocols continue to advance, this approach and similar viewport-dependent strategies play a crucial role in delivering high-quality 360-degree video content.