99 research outputs found
Multiple description video coding for real-time applications using HEVC
Remote control vehicles require the transmission of large amounts of data,
and video is one of the most important sources for the driver. To ensure
reliable video transmission, the encoded video stream is transmitted
simultaneously over multiple channels. However, this solution incurs a high
transmission cost due to the wireless channel's unreliable and random bit loss
characteristics. To address this issue, it is necessary to use more efficient
video encoding methods that can make the video stream robust to noise. In this
paper, we propose a low-complexity, low-latency 2-channel Multiple Description
Coding (MDC) solution with an adaptive Instantaneous Decoder Refresh (IDR)
frame period, which is compatible with the HEVC standard. This method shows
better resistance to high packet loss rates with lower complexity
High efficiency compression for object detection
Image and video compression has traditionally been tailored to human vision.
However, modern applications such as visual analytics and surveillance rely on
computers seeing and analyzing the images before (or instead of) humans. For
these applications, it is important to adjust compression to computer vision.
In this paper we present a bit allocation and rate control strategy that is
tailored to object detection. Using the initial convolutional layers of a
state-of-the-art object detector, we create an importance map that can guide
bit allocation to areas that are important for object detection. The proposed
method enables bit rate savings of 7% or more compared to default HEVC, at the
equivalent object detection rate.Comment: The paper is published in IEEE ICASSP 18
Efficient HEVC-based video adaptation using transcoding
In a video transmission system, it is important to take into account the great diversity of the network/end-user constraints. On the one hand, video content is typically streamed over a network that is characterized by different bandwidth capacities. In many cases, the bandwidth is insufficient to transfer the video at its original quality. On the other hand, a single video is often played by multiple devices like PCs, laptops, and cell phones. Obviously, a single video would not satisfy their different constraints.
These diversities of the network and devices capacity lead to the need for video adaptation techniques, e.g., a reduction of the bit rate or spatial resolution. Video transcoding, which modifies a property of the video without the change of the coding format, has been well-known as an efficient adaptation solution. However, this approach comes along with a high computational complexity, resulting in huge energy consumption in the network and possibly network latency.
This presentation provides several optimization strategies for the transcoding process of HEVC (the latest High Efficiency Video Coding standard) video streams. First, the computational complexity of a bit rate transcoder (transrater) is reduced. We proposed several techniques to speed-up the encoder of a transrater, notably a machine-learning-based approach and a novel coding-mode evaluation strategy have been proposed. Moreover, the motion estimation process of the encoder has been optimized with the use of decision theory and the proposed fast search patterns. Second, the issues and challenges of a spatial transcoder have been solved by using machine-learning algorithms. Thanks to their great performance, the proposed techniques are expected to significantly help HEVC gain popularity in a wide range of modern multimedia applications
A Decoding-Complexity and Rate-Controlled Video-Coding Algorithm for HEVC
Video playback on mobile consumer electronic (CE) devices is plagued by fluctuations in the network bandwidth and by limitations in processing and energy availability at the individual devices. Seen as a potential solution, the state-of-the-art adaptive streaming mechanisms address the first aspect, yet the efficient control of the decoding-complexity and the energy use when decoding the video remain unaddressed. The quality of experience (QoE) of the end-users’ experiences, however, depends on the capability to adapt the bit streams to both these constraints (i.e., network bandwidth and device’s energy availability). As a solution, this paper proposes an encoding framework that is capable of generating video bit streams with arbitrary bit rates and decoding-complexity levels using a decoding-complexity–rate–distortion model. The proposed algorithm allocates rate and decoding-complexity levels across frames and coding tree units (CTUs) and adaptively derives the CTU-level coding parameters to achieve their imposed targets with minimal distortion. The experimental results reveal that the proposed algorithm can achieve the target bit rate and the decoding-complexity with 0.4% and 1.78% average errors, respectively, for multiple bit rate and decoding-complexity levels. The proposed algorithm also demonstrates a stable frame-wise rate and decoding-complexity control capability when achieving a decoding-complexity reduction of 10.11 (%/dB). The resultant decoding-complexity reduction translates into an overall energy-consumption reduction of up to 10.52 (%/dB) for a 1 dB peak signal-to-noise ratio (PSNR) quality loss compared to the HM 16.0 encoded bit streams
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