![]() In this case, digital systems adapt their transmission rate to the worst receiver, thus penalizing the receivers that could obtain higher quality. One such scenario is wireless multicast transmission in which the receivers have different channel quality levels. At reception, the inverse operations are carried out to recover the blocks of pixels and to reconstruct the original video sequence.Īlthough all-digital video systems usually offer the best transmission characteristics for any media due to the great research progress over the last decades, the analog encoding and transmission of video in certain scenarios offers important advantages. Finally, prior to its transmission, the symbols are shuffled with a Hadamard matrix in order to equalize the frame quality. Next, the transmitted coefficients are protected against noise with an analog mapping. In order to take advantage of video spatial and temporal redundancy, first, the video sequence is split into blocks, applying to them a discrete cosine transform (DCT). JSCC-Cast extends our previous work on coding and transmission of still images based on analog joint source channel coding (AJSCC) techniques. In order to address this objective, JSCC-Cast is proposed, which is a low-complexity scheme for encoding analog video with negligible digital metadata and with special emphasis on its suitability for Internet of things (IoT) systems. This paper investigates a functional scheme in order to reduce the bandwidth required by raw video transmission over channels with limited capacity while keeping an acceptable video quality level. In summary, analog encoding and transmission video systems are simpler than their all-digital equivalents since the transmission is the same for all receivers, and no feedback channel is required. In particular, with the growth of the Internet of Things, the use of simple microprocessors with very low power consumption is expanding, thus requiring systems with ultra-low complexity and computational load. This makes it necessary to develop advanced video coding and transmission systems. Video visualization on different types of fixed and mobile devices is growing every year. ![]() Moreover, in some circumstances, the JSCC-Cast obtains a perceived quality for the frames comparable to those displayed by the digital one. ![]() The results show that, depending on the scenario and considering image quality metrics such as the structural similarity index measure, the peak signal-to-noise ratio, and the perceived quality of the video, JSCC-Cast exhibits a performance close to that of Softcast but with less metadata and not requiring a feedback channel in order to track channel variations. ![]() JSCC-Cast is compared to Softcast, which is considered the benchmark for analog and hybrid video coding, and with an all-digital H.265-based encoder. Its design is based on the use of linear transforms that exploit the spatial and temporal redundancy and the analog encoding of the transformed coefficients with different protection levels depending on their relevance. The proposed system exhibits a similar image quality compared to existing analog and hybrid encoding alternatives such as Softcast. Suitable applications for JSCC-Cast are multicast transmissions over time-varying channels and Internet of Things wireless connectivity of end devices having severe constraints on their computational capabilities. This work considers the design and practical implementation of JSCC-Cast, a comprehensive analog video encoding and transmission system requiring a reduced amount of digital metadata. ![]()
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