基于MPC的音视频同步码率自适应测试

随着信息化的发展,音视频流媒体技术应用面越来越广,为了使得音视频流媒体技术尤其是在直播方面拥有更好的性能,得到更多用户的好评,采用在原本HTTP的动态自适应流标准的视频流媒体架构下引入MPC控制算法并将MPC与码率自适应算法相结合的方法,进行对AAC优化、确定预测模型、测试音视频同步的影响因素以及PSNR-Y分量、测试切片时长与跳帧时延,计算最终的QoE用户评价指标来进一步检测音视频流媒体技术的优劣;经实验仿真测试可知,相比前人的相关算法,在不同直播场景下以及不同网络环境下均有更加良好的QoE值,平均QoE用户评价指标明显更高,为1 237.282 6;综上分析可知,MPC的音视频同步码率自适应算法各项性能最好。

基于DVB+IP的境外数字电视全业务融合播出平台模型设计

江苏省广电有线信息网络股份有限公司无锡分公司设计了一套基于数字视频广播(Digital Video Broadcast,DVB)+网际互连协议(Internet Protocol,IP)的数字电视全业务融合播出平台模型。在此基础上,根据项目部署地的实际需求,设计并完成项目一期工程的数字电视前端系统。详细介绍全系统包含卫星电视节目的信号接收、无锡地区电视节目的 IP传输、自办节目播出、电子节目单(Electrical Program Guide,EPG)开机广告、信号复用、信号调制以及信号分配等功能。

地铁高清视频监控系统存储扩容方案研究

武汉轨道交通线网部分线路设计和开通年限较长,无法满足《防恐法》公共区域及重点部位视频监控图像信息保存期限不少于90天的要求。研究立足于城市轨道交通运营实际,提出一种基于ONVIF协议的辅码流异地备份存储方案,实现了对既有高清视频监控系统的存储扩容。该方案已应用于武汉轨道交通某三线换乘站,相比本地存储扩容方案具有实施简单、对运营影响小、改造成本低的优势,对城市轨道交通高清视频监控系统存储90天扩容改造具有一定的指导意义。

IP网络架构下无压缩4K视频码流的PTP同步信号解析

随着网络技术的发展,数据码流传输模式逐步由SDI架构过渡至IP化架构,简化了网络结构,提升了传输效率,但同时对发射端和接收端的同步问题提出了更高要求。本文针对IP网络架构下无压缩4K视频码流的同步问题,基于PTP协议对同步信号和RTP信号进行解析,进一步理清RTP和PTP协议协同工作时视频码流时钟与源时钟的同步关系。

基于RTMP的森林火灾预警监控系统设计

高温是森林火灾发生的主要原因之一,对林区进行分布式温度监测是提早发现火灾隐患的有效途径。设计了一种使用Linux系统和实时传输协议进行温度等环境参数检测的森林火灾预警监控系统,系统终端节点集成温湿度、位置和视频采集功能,利用TCP和RTMP协议实现多个分布式终端节点数据和视频流的实时传输,在监控端实时监测多个地点的环境数据,排查潜在的火灾隐患。通过3个节点的测试,系统可以实现终端节点数据、视频汇聚,且使用FFmpeg进行视频拉流比传统VLC拉流速度快约10秒。

WebRTC协议在线上教学中的应用实践

为加快教育数字化转型和完善教学信息化供给侧结构性改革,本文提出了一个用于日常实时视频教学的软件解决方案。该方案基于WebRTC协议及其对应的开源软件框架,利用WebRTC协议作为HTML5标准子集并聚焦音视频实时通信场景,依托浏览器-服务器模式构建适用于网页在线音视频会议和教学的架构模型。方案的实现可有效推进教育数字化转型。

基于SIP的铁路云视频会议系统优化方案研究

针对当前铁路云视频会议系统内外网音视频信息传输性能存在不足、国铁集团各级单位常态化应用模式下视频会议需求持续增加等问题,结合系统使用特点,采用比H.323协议更具优势的会话初始协议(SIP)优化音视频信息传输技术,通过搭建最小功能单元测试系统对各项功能进行测试,验证了系统会议功能得以丰富和完善,传输时延等关键性能得以提升。同时,对比分析集中式、二级平台(同构/异构)、分布式和背靠背等部署模式的优缺点,提出基于SIP的系统总体架构部署方案,为未来系统实现扩容升级提供有利的技术支撑。

铁路应急通信系统视频流卡顿问题分析

针对某铁路局应急通信系统转发视频流至国铁集团应急通信系统时出现视频卡顿的问题,利用数据网业务质量智能感知系统对应急通信视频业务进行监控分析,确定视频卡顿原因,提出采用RTP+实时传输控制协议(Real-Time Control Protocol,RTCP)传输UDP数据包以保证视频流数据传输可靠有序的解决方案。

Performance Evaluation of an Internet Protocol Security (IPSec) Based Multiprotocol Label Switching (MPLS) Virtual Private Network

This paper evaluates the performance of Internet Protocol Security (IPSec) based Multiprotocol Label Switching (MPLS) virtual private network (VPN) in a small to medium sized organization. The demand for security in data networks has been increasing owing to the high cyber attacks and potential risks associated with networks spread over distant geographical locations. The MPLS networks ride on the public network backbone that is porous and highly susceptible to attacks and so the need for reliable security mechanisms to be part of the deployment plan. The evaluation criteria concentrated on Voice over Internet Protocol (VoIP) and Video conferencing with keen interest in jitter, end to end delivery and general data flow. This study used both structured questionnaire and observation methods. The structured questionnaire was administered to a group of 70 VPN users in a company. This provided the study with precise responses. The observation method was used in data simulations using OPNET Version 14.5 Simulation software. The results show that the IPSec features increase the size of data packets by approximately 9.98% translating into approximately 90.02% effectiveness. The tests showed that the performance metrics are all well within the recommended standards. The IPSec Based MPLS Virtual private network is more stable and secure than one without IPSec.

The Formal Specifications for Protocols of Decoders

This paper presents a formal approach, FSPD (Formal Specifications for Protocols of Decoders), to specify decoder communication protocols. Based on axiomatic, FSPD is a precise language with which programmers could use only one suitable driver to handle various types of decoders. FSPD is helpful for programmers to get high adaptability and reusability of decoder-driver software. Key words formalization - digital video security system - protocol of decoders CLC number TP 311 Biography: YUAN Meng-ting(1976-), Ph.D candidate, research direction: software engineering, formal method.

Optimization of Coral Video Transect Technique for Coral Reef Survey: Comparison with Intercept Transect Technique

Variety in video sampling protocol for coral reef survey worldwide has prompted this study to?create an optimized protocol for Coral Video Transect (CVT) technique for coral reef survey in Malaysia. The effect of different vertical distance of the camera above the substrate during video recording, number of frames and points analyzed as well as time spent during field and analysis were examined to determine an optimal protocol for CVT technique at different coral reef conditions in Malaysia’s water. Video recording taken at 0.5 m camera distance was selected as optimize vertical distance above the substrate as it can identify more benthic categories than 1.0 m with lesser time taken as well as frames extracted than 0.2 m. Respectively, 80% of total frames extracted from 20 m transect and analyzed with 50 points per frames were chosen as an optimized sample size for its ability to precisely estimate percent cover and accurately identify benthic categories.?This optimized protocol was then compared with Line Intercept Transect (LIT) method. No clear difference in estimating percentage cover of major benthic categories between CVT and LIT method, but CVT recorded a significantly higher number of benthic categories with lesser time spent during field survey as compared to LIT method. This implied that the optimize CVT method can precisely estimate percent cover and accurately identify benthic categories in coral communities and are thus more suitable for scientific research and management purposes than LIT method. Other advantages of using this technique are by providing a permanent data that can be reassessed later on, lesser field time and wider survey area. Overall, this study showed that CVT technique is an acceptable alternative method of coral reef survey in Malaysia.

RTP payload format for H.264/SVC scalable video coding

The scalable extension of H.264/AVC, known as scalable video coding or SVC, is currently the main focus of the Joint Video Team’s work. In its present working draft, the higher level syntax of SVC follows the design principles of H.264/AVC. Self-contained network abstraction layer units (NAL units) form natural entities for packetization. The SVC specification is by no means finalized yet, but nevertheless the work towards an optimized RTP payload format has already started. RFC 3984, the RTP payload specification for H.264/AVC has been taken as a starting point, but it became quickly clear that the scalable features of SVC require adaptation in at least the areas of capability/operation point signaling and documentation of the extended NAL unit header. This paper first gives an overview of the history of scalable video coding, and then reviews the video coding layer (VCL) and NAL of the latest SVC draft specification. Finally, it discusses different aspects of the draft SVC RTP payload format, in- cluding the design criteria, use cases, signaling and payload structure.

Streaming and congestion control using scalable video coding based on H.264/AVC

This paper presents a streaming system using scalable video coding based on H.264/AVC. The system provides a congestion control algorithm supported by channel bandwidth estimation of the client. It uses retransmission only for packets of the base layer to disburden the congested network. The bandwidth estimation allows for adjusting the transmission rate quickly to the current available bandwidth of the network. Compared to binomial congestion control, the proposed system allows for shorter start-up times and data rate adaptation. The paper describes the components of this streaming system and the results of experiments showing that the proposed approach works effectively for streaming video.

Efficient video-on-demand services over mobile datacast channels

The integration of reliable Video-on-Demand (VoD) broadcasting schemes in the DVB-h transmission system is studied, exemplary for Pyramid Broadcasting (PB). Sophisticated VoD broadcasting schemes such as PB allow receivers to tune into the ongoing transmission of a video-stream at arbitrary time, while still being able to receive the multimedia sequence from the beginning to end, after a short initial playout latency. Raptor coding, integrated in the FLUTE protocol, is combined with the traditional PB scheme in order to provide high service and presentation reliability. We give a short overview on the DVB-h transmission system as well as on the FLUTE protocol. We present and discuss options for the integration of VoD broadcasting schemes in combination with Raptor coding. We achieve backward-compatibility even with terminals not supporting Raptor coding. Simulation results show the benefits of the discussed VoD scheme compared to existing carousel approaches in DVB-h.

Dante网络音频传输协议在视频会议上的应用

2021年,某政务单位在升级视频会议系统时采用了Dante网络音频传输技术,提供了一种整体解决方案。该技术在以太网(Ethernet)网络中能够同时发送和接收多个音频通道。Dante音频传输无杂音、传输速度快、精度高且成本低,点对点传输基本接近于零延迟,通常可以通过双绞网线替代音频线路,节省成本。同时,Dante技术可以通过网络层以网际协议(Internet Protocol,IP)的形式实现音频通信,使得音频数据与会议相关数字信号互不干扰,兼容不同型号的音频设备。通过Dante网络音频传输技术的实施,解决了音频在项目实施期间的很多难题。

VCSW—An RTP/RTCP-Based Video Conferencing System On WAN

This paper chiefly introduces the model of Video Conferencing System, H.323 standard of ITU- T and RTP/RTCP protocol, and realizes a WAN- Oriented Video Conferencing System—VCSW (Video Conferencing System on WAN). In VCSW, RTP/RTCP pro- tocol is used for transporting media data and video conference on WAN can be established, so VCSW has abroad application scope. This paper stresses analyzing RTP/RTCP protocol, realizes it and modifies some details of it according to our device condition: re- duces some fields of RTP and RTCP header, removes some information managed by RTP/RTCP. Consequently in testing of lab, good effect is achieved.

地下道勘测机器人的设计与制作

设计并制作一款用于城市中地下道的勘测和垃圾清理的机器人。该机器人以STM32单片机为主控芯片,用英伟达工控机进行视频传输。PC端与主控系统组成远程控制系统,PC端与4G模块通过TCP协议广域网连接,4G模块接收信息再通过串口发送到主控系统上。PC端与英伟达工控机组成远程监控系统,PC端通过TCP/IP协议局域网与英伟达工控机连接,英伟达工控机采集视频通过局域网发送给PC端,PC端接收图像并通过窗口实时显示。还基于PyQt开发了一款把远程控制和远程视频监控集成一体的上位机软件,通过上位机软件可以方便用户操作和使用机器人。经过调试,PC端与机器人成功建立通信并可以实时传回视频画面,机械臂成功实现夹取功能。能完成勘测和清理地下道的任务。

轨道交通视频监控多协议注册存储灾备的改造研究与应用

城市轨道交通既有线路全数字视频监控系统大部分采用IPSAN存储,由于IPSAN控制器本身处理能力或者品牌性能配置差异的限制,IPSAN接收的视频存储流主要依靠具有流媒体功能的管理服务器进行视频流转发。文章主要剖析了全数字视频监控系统网络结构和媒体流转发存储方式的缺点,阐述了摄像机通过ONVIF或国标协议等多协议异地平台再注册的系统原理、异地灾备改造内容以及实现单站点实时画面及录像异地灾备的优势。

音视频传输技术探讨

随着信息技术的发展,音视频应用场景越来越多,传输需求越来越大。针对音视频传输技术现状进行总结,分析各种技术的优缺点和应用场景,列举音视频技术发展面临的问题,并针对这些问题提出一些建议,为相关从业人员提供参考。

音视频IP协议在广播电视台业务融合中的应用研究

在广播电视业务发展中,音视频网际协议(Internet Protocol,IP)框架可以有效解决广播和电视之间的业务融合问题。针对IP音视频技术在广播电视台业务融合中的应用开展研究,探讨音视频IP协议框架在广播电视台业务融合中的价值,并以宁波广播电视集团设计开发的ST2110音视频IP协议为研究对象,分析ST2110音视频IP协议在广播电视台业务融合中的应用,提出实现广播电视业务融合发展的保障性措施,进一步促进广播电视业务的高质量融合化发展。