Recently, soft video multicasting has gained a lot of attention, especially in broadcast and mobile scenarios where the bit rate supported by the channel may differ across receivers, and may vary quickly over time. Unlike the conventional designs that force the source to use a single bit rate according to the receiver with the worst channel quality, soft video delivery schemes transmit the video such that the video quality at each receiver is commensurate with its specific instantaneous channel quality. In this paper, we present a soft video multicasting system using an adaptive block-based compressed sensing (BCS) method. The proposed system consists of an encoder, a transmission system, and a decoder. At the encoder side, each block in each frame of the input video is adaptively sampled with a rate that depends on the texture complexity and visual saliency of the block. The obtained BCS samples are then placed into several packets, and the packets are transmitted via a channel-aware OFDM (orthogonal frequency division multiplexing) transmission system with a number of subchannels. At the decoder side, the received BCS samples are first used to build an initial approximation of the transmitted frame. To further improve the reconstruction quality, an iterative BCS reconstruction algorithm is then proposed that uses an adaptive transform and an adaptive soft-thresholding operator, which exploits the temporal similarity between adjacent frames to achieve better reconstruction quality. The extensive objective and subjective experimental results indicate the superiority of the proposed system over the state-of-the-art soft video multicasting systems.

中文翻译：

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使用自适应压缩感知的软视频多播

最近，软视频组播获得了很多关注，特别是在广播和移动场景中，信道支持的比特率可能因接收器而异，并且可能随时间快速变化。与根据具有最差信道质量的接收器强制源使用单个比特率的传统设计不同，软视频传输方案传输视频使得每个接收器的视频质量与其特定的瞬时信道质量相称。在本文中，我们提出了一种使用基于块的自适应压缩感知 (BCS) 方法的软视频多播系统。所提出的系统由编码器、传输系统和解码器组成。在编码器端，输入视频的每一帧中的每个块都以取决于块的纹理复杂性和视觉显着性的速率进行自适应采样。然后将获得的 BCS 样本放入多个数据包中，并通过具有多个子信道的信道感知 OFDM（正交频分复用）传输系统传输这些数据包。在解码器端，接收到的 BCS 样本首先用于构建传输帧的初始近似值。为了进一步提高重建质量，随后提出了一种迭代 BCS 重建算法，该算法使用自适应变换和自适应软阈值算子，利用相邻帧之间的时间相似性来实现更好的重建质量。