Perfect requantization for video transcoding

Bit rate adaptation is one of the most important types of video transcoding. In this paper, we investigate certain critical points in the spectrum of rate shaping requests. We show that the selection of quantization step sizes may not have monotonic effects on rate-distortion characteristics in the transcoding sense. In other words, rate-distortion tradeoff for transcoding which operates on an already-compressed source can be different than that for regular encoding which operates on an original source. We show in a generic form that careful selections of the step size can lead to much improved performance for transcoding, especially when comparing to what would have been produced through a direct encoding. We demonstrate this unique rate-distortion characteristic through simulations as well as real transcoding scenario with H.264 sequences.

低复杂度的MPEG-2到H.264快速转码算法

提出一种新的MPEG-2到H.264快速转码算法,利用H.264宏块（MB）模式选择与MPEG-2运动补偿残差间的相关性,将H.264宏块模式的选择转化为数据分类;在MPEG-2解码时,保存相关的宏块信息,包括MB编码模式、编码块类型（CBPC）、MB残差的均值和方差,解码后采用标准的H.264编码器对YUV图像编码,并保存H.264宏块的编码模式,采用机器学习算法得到决策树,用于H.264编码模式的分类,从而大大提高转码效率。     

一种MPEG-2到AVS帧内转码的快速模式选择算法

根据到在变换域中块系数分布能够表达空间方向上的频率分布特性,提出了一种基于变换域系数分布特性与空间方向频率特性之间的对应关系的快速帧内预测编转码算法.实验结果表明该方法能极大的减少帧内转码的计算量,转码视频质量几乎不变.     

Efficient video quality assessment for on-demand video transcoding using intensity variation analysis

The Journal of Supercomputing - Due to the wide spread usage of smart devices, adopting video contents service to the diverse end user’s service environment is an essential process. The...     

一种基于H.264的混合视频转码方法*

为了提高比特率缩减的H.264视频转码速度,提出了一种混合型视频转码（mixtue video transcode,MVT）方法。该方法选择串联结构对intra帧进行转换编码,选择开环结构对inter帧进行转换编码,同时对inter帧进行部分误差消除操作。对intra帧,转换编码操作后可以得到无误差的intra帧;对于inter帧,转码后图像质量的损失大于串联结构,但因为进行了消除误差漂移的操作,这一损失可以控制在可接受的最小范围内。实验结果表明,提出的混合型视频转码结构在转码速度上远远高于串联结构,转     

基于Hadoop视频转码缓存策略的研究

针对实时云转码系统中已转码的媒体文件重新使用率不高的情况,引入转码缓存机制,提出一种缓存替换策略。采用云存储空间缓存视频,根据视频资源的流行度、请求间隔、视频大小和未来被访问概率计算视频的效能函数值,当缓存空间不足时替换出效能值较小的视频。实验结果表明,与传统置换算法LRU、LFU和FIFO相比,该策略的资源请求命中率分别提高了2?6％,4?3％和9?2％,在一定程度上缩短了视频分发延迟,减少了用户响应时间。     

Efficient segment-based video transcoding proxy for mobile multimedia services

To support various bandwidth requirements for mobile multimedia services for future heterogeneous mobile environments, such as portable notebooks, personal digital assistants (PDAs), and 3G cellular phones, a transcoding video proxy is usually necessary to provide mobile clients with adapted video streams by not only transcoding videos to meet different needs on demand, but also caching them for later use. Traditional proxy technology is not applicable to a video proxy because it is less cost-effective to cache the complete videos to fit all kinds of clients in the proxy. Since transcoded video objects have inheritance dependency between different bit-rate versions, we can use this property to amortize the retransmission overhead from transcoding other objects cached in the proxy. In this paper, we propose the object relation graph (ORG) to manage the static relationships between video versions and an efficient replacement algorithm to dynamically manage video segments cached in the proxy. Specifically, we formulate a transcoding time constrained profit function to evaluate the profit from caching each version of an object. The profit function considers not only the sum of the costs of caching individual versions of an object, but also the transcoding relationship among these versions. In addition, an effective data structure, cached object relation tree (CORT), is designed to facilitate the management of multiple versions of different objects cached in the transcoding proxy. Experimental results show that the proposed algorithm outperforms companion schemes in terms of the byte-hit ratios and the startup latency.     

Overlapping boundary based multimedia slice transcoding method and its system for medical video and traffic video

This paper is concerned about the field of multimedia transcoding technology. This paper provides a method for multimedia slice transcoding. This method is detailed as follows: the multimedia is segmented according to the preset unit to obtain large numbers of slices; the length of the slices’ fuzzy area is acquired; both ends of each slice is made redundant for fuzzy area length; the slices after redundancy are transcoded; the redundant fuzzy area length at both ends of transcoded slice is cut; the slices of cut fuzzy area length are spliced. The method for multimedia slice transcoding stated in this paper can remove the boundary fuzzy area when the transcoded slices are spliced in order to obtain more satisfactory multimedia effects.     

一种基于LVS的视频转码调度算法的研究与设计

随着国家大力推进三网融合,手持终端设备可以通过3G网络方便地浏览互联网上丰富的视频信息,但视频格式的多样化给用户浏览带来了诸多不便。通过对Linux虚拟服务器(LVS)调度算法的研究与分析,提出了一种改进的动态负载均衡算法ADLBA,并通过实验验证了该算法的可行性和有效性。     

Multilayer transcoding with format portability for multicasting of single-layered video

This paper proposes a novel multilayer video transcoding approach for multicasting pre-encoded video to heterogeneous end-systems via diverse grouping of networks. Multilayer transcoding is first addressed by means of multiquality or SNR scalability of the MPEG-2 standard. Frequency domain transcoding and drift-compensated transcoding are derived from the closed-loop and multiloop SNR scalabilities, respectively. The proposed transcoding architectures are verified in terms of eliminating picture drift whilst preserving compatibility with the MPEG-2 SNR decoder. Multilayer transcoding is then addressed by means of multiresolution or spatial scalability of the MPEG-2 standard that supports different video formats. The transcoder retains the full resolution of the incoming video stream in its enhancement layer while generating a low spatio-temporal resolution base-layer compatible with the H.263 video format. Hence providing both multilayer transcoding and video format portability. The resultant video layers are shown to be free from drift with PSNR results comparable to those of the respective scalable encoders.     

A secure framework of the surveillance video network integrating heterogeneous video formats and protocols

Recently, IT technologies are becoming focused on different traditional industries. The large scaled intelligent video surveillance system is one of them and it integrates a large number of digitalized CCTV [1] devices through the Web. However, existing video devices have been deployed for many years by different vendors as different models with different specifications. To integrate these heterogeneous devices, the centralized management server (CMS) and its clients need a specialized architecture to deal with different types of media encodings and connection protocols etc. In particular, well-defined access control mechanism is required for a large scaled surveillance video network. In this paper, we designed and implemented a server that incorporates the architecture integrating and delivering multiple video streams from different types of video devices to multiple clients and securing the access to the video streams.     

Complexity of cloud-based transcoding platform for scalable and effective video streaming services

Nowadays, a fast network improves the quality of our daily life and we can enjoy a variety of services over the Internet. Different types of media streaming services have been proposed and utilized as the network speed is now sufficiently fast to deliver high-quality live streaming. Usually, different media streaming services deliver streaming data by using different protocols such as the real-time message protocol (RTMP), real-time streaming protocol (RTSP), and Windows media HTTP streaming protocol (WMSP). In this paper, we propose and implement a cloud-based scalable and cost-effective video streaming transcoding service platform to provide the service of changing real-time streaming protocols (RTMP/RTSP) and codecs (H.263/H.264). A transcoder dispatching problem (TDP) over the cloud platform is also defined, which attempts to serve all the transcoding requests by minimizing the cost of virtual machines. Further, a transcoder dispatching algorithm and an online transcoder dispatching algorithm are proposed for the TDP. These algorithms are implemented on the Amazon EC2 platform. Experimental results demonstrate that by renting different levels of virtual machines dynamically and intelligently, we can provide a scalable and cost-effective transcoding service for bridging heterogeneous streaming media.     

基于多尺寸特征融合的快速转码算法

为了降低H.264转码器的运算复杂度,满足视频转码实时应用的要求,提出一种结合多尺寸视频特征的快速视频转码帧内预测算法。首先利用二维直方图提取小尺寸视频中宏块的空间特性,结合双阈值的方法,选择Intra 16×16或Intra 4×4模式。然后从输入的视频码流中提取编码信息组成多维特征向量训练支持向量机(SVM)分类器模型,通过SVM建立大尺寸视频编码信息与小尺寸视频宏块编码模式之间的联系,进而对Intra 4×4中的9种模式进行细分。此算法减少了预测模式数量,实现率失真优化算法的提前终止,在高效转码的同时保证了转码后视频的高质量。     

Fast video transcoding from H.263 to H.264/MPEG-4 AVC

In the past 10 years detailed works on different video transcoders have been published. However, the new ITU-T Recommendation H.264—also adapted as ISO/IEC MPEG-4 Part 10 (AVC)—provides many new encoding options for the prediction processes that lead to difficulties for low complexity transcoding. In this work we present very fast transcoding techniques to convert H.263 bitstreams into H.264/AVC bitstreams. We will give reasoning, why the proposed pixel domain approach is advantageous in this scenario instead of using a DCT domain transcoder. Our approach results in less than 9% higher data rate at equivalent PSNR quality compared to a full-search approach. But this rate loss allows the reduction of the search complexity by a factor of over 200 for inter frames and still a reduction of over 70% for intra frames. A comparison to a fast search algorithm is given. We also provide simulation results that our algorithm works for transcoding MPEG-2 to H.264/AVC in the aimed scenario.

An integrated source transcoding and congestion control paradigmfor video streaming in the Internet

In this work we present an end-to-end optimized video streaming system comprising of synergistic interaction between a source packetization strategy and an efficient and responsive, TCP-friendly congestion control protocol [Linear Increase Multiplicative Decrease with History (LIMD/H)]. The proposed source packetization scheme transforms a scalable/layered video bitstream so as to provide graceful resilience to network packet drops. The congestion control mechanism provides low variation in transmission rate in steady state and at the same time is reactive and provably TCP-friendly. While the two constituent algorithms identified above are novel in their own right, a key aspect of this work is the integration of these algorithms in a simple yet effective framework. This “application-transport” layer interaction approach is used to maximize the expected delivered video quality at the receiver. The integrated framework allows our system to gracefully tolerate and quickly react to sudden changes in the available connection capacity due to the onset of congestion, as verified in our simulations     

Comparison of HDTV formats using objective video quality measures

In this paper we compare some of the objective quality measures with subjective, in several HDTV formats, to be able to grade the quality of the objective measures. Also, comparison of objective and subjective measures between progressive and interlaced video signal will be presented to determine which scanning emission format is better, even if it has different resolution format. Several objective quality measures will be tested, to examine the correlation with the subjective test, using various performance measures.     

H.264视频流分辨率缩减转码的快速宏块模式选择算法

H.264视频编码标准采用帧内预测,帧间的宏块分割等新的特性提高了编码效率,同时也较大地提高了模式选择的复杂度,因此H.264视频转码中模式选择算法将显著影响到转码的效率。提出了一种适用于H.264视频流空间分辨率缩减转码的宏块模式选择算法。主要利用输入码流中的宏块模式和运动矢量信息,获得局部的预测方向或者梯度方向,从而根据方向信息,减少需要计算的宏块模式的数目。实验证明,在保持编码效率和视频质量的同时,能够有效地降低H.264下采样转码过程中的宏块模式选择算法的复杂度。     

A big video data transcoding service for social media over federated clouds

Multimedia Tools and Applications - Nowadays, the advent of social networks have revolutionised the traditional communication media. In recent years, the number of social media providers has...     

Multipath routing and rate-controlled video encoding in wireless video surveillance networks

Video surveillance systems typically consist of many video sources distributed over a wide area, transmitting live video streams to a central location for processing and monitoring. The target of this paper—to bring down the overall system cost and increase feasibility, scalability, and performance—is to propose a new architecture for a wireless video surveillance network, whose telecommunication infrastructure is based on a wireless mesh network, and where video sources are able to estimate network bandwidth and consequently control their output rate. Multipath routing is applied in such a way that at least part of the information arrives at its destination even if a wireless link is shielded (maliciously or not). A case study is considered to discuss the performance of the proposed architecture, analyzing a comparison between single-path and multipath approaches.