FreeCast: Graceful Free-Viewpoint Video Delivery
FreeCast: Graceful Free-Viewpoint Video Delivery
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DOI：
10.1109/tmm.2018.2870074
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发表时间：
2019-04
影响因子：
7.3
通讯作者：
T. Fujihashi;T. Koike-Akino;Takashi Watanabe;P. Orlik
中科院分区：
文献类型：
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作者：
T. Fujihashi;T. Koike-Akino;Takashi Watanabe;P. Orlik
无线多视图加深度（MVD）视频流传输使得能够在无线设备上进行自由视点视频回放，其中观看者可以从接收到的MVD帧自由地合成任何优选的虚拟视点。无线MVD流传输的现有方案使用基于数字的压缩来实现更好的编码效率。然而，基于数字的方案具有称为悬崖效应的问题，其中视频质量在无线信道质量方面是阶跃函数。此外，跨MVD帧分配量化电平和传输功率的参数优化是麻烦的。为了实现高质量的无线MVD视频流，我们提出了一种新的优雅的视频传输方案，称为FreeCast。FreeCast直接传输基于5-D离散余弦变换的线性变换信号，无需数字量化和熵编码操作。此外，我们利用一个多维高斯马尔可夫随机场模型的基础上的拟合函数的开销减少，以减轻率和功率损失，由于大的开销。所提出的FreeCast实现优美的视频质量的无线信道质量的改善下，低开销的要求。此外，通过仅控制传输功率分配，可以简化实现最高视频质量的参数优化。几个测试MVD视频序列的性能结果表明，FreeCast通过显着降低开销量，在带宽有限的环境中产生更好的视频质量。例如，FreeCast的结构相似性（SSIM）性能在无线信道质量上比现有的优美视频递送方案高大约0.127，即，在37.5 Msymbols/s的传输符号速率下，信噪比为0-25 dB。
Wireless multi-view plus depth (MVD) video streaming enables free viewpoint video playback on wireless devices, where a viewer can freely synthesize any preferred virtual viewpoint from the received MVD frames. Existing schemes of wireless MVD streaming use digital-based compression to achieve better coding efficiency. However, the digital-based schemes have an issue called the cliff effect, where the video quality is a step function in terms of wireless channel quality. In addition, parameter optimization to assign quantization levels and transmission power across MVD frames are cumbersome. To realize high-quality wireless MVD video streaming, we propose a novel graceful video delivery scheme, called FreeCast. FreeCast directly transmits linear-transformed signals based on 5-D discrete cosine transform, without digital quantization and entropy coding operations. In addition, we exploit a fitting function based on a multidimensional Gaussian Markov random field model for overhead reduction to mitigate rate and power loss due to large overhead. The proposed FreeCast achieves graceful video quality with the improvement of wireless channel quality under a low overhead requirement. In addition, the parameter optimization to achieve highest video quality can be simplified by only controlling a transmission power assignment. Performance results with several test MVD video sequences show that FreeCast yields better video quality in band-limited environments by significantly decreasing the amount of overhead. For instance, structural similarity (SSIM) performance of FreeCast is approximately 0.127 higher than the existing graceful video delivery schemes across wireless channel quality, i.e., signal-to-noise ratio, of 0–25 dB at a transmission symbol rate of 37.5 Msymbols/s.