The VLC media player includes file cache and stream buffer options to enable fine-grained control over video playback on machines with limited system resources. If you use VLC to stream network video, you can set the buffer size on a per-stream or permanent basis. For local file playback, you can […]
Yearly Archives: 2015
As you may know, to be a robust meeting entity, we must take good care of compatibility requirements for different facilities from different manufacturers. In H.323 protocol, we can use fields like Vendor ID, Product ID, Version ID in the signaling commands. But how to do this when you are using SIP protocol? Definitions in RFC 3261 20.35 Server The Server header field contains information about the software used by the UAS to handle the request. Revealing the specific software version of the server might allow the server to become more vulnerable to attacks against software that is known to contain security holes. Implementers SHOULD make the Server header field a configurable option. Example: Server: HomeServer v2 20.41 User-Agent The User-Agent header field contains information about the UAC originating the request. The semantics of this header field are defined in [H14.43]. Revealing the specific software version of the user agent might allow the user agent to become more vulnerable to attacks against software that is known to contain security holes. Implementers SHOULD make the User-Agent header field a configurable option. Example: User-Agent: Softphone Beta1.5 [H14.43] User-Agent definition in RFC2616 14.43 User-Agent The User-Agent request-header field contains information about the user agent originating the request. This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular user agent limitations. User agents SHOULD include this field with requests. The field can contain multiple product tokens (section 3.8) and comments identifying the agent and any subproducts which form a significant part of the user agent. By convention, the product tokens are listed in order of their significance for identifying the application. User-Agent = “User-Agent” “:” 1*( product | comment ) Example: User-Agent: CERN-LineMode/2.15 libwww/2.17b3 How TANDBERG and Polycom implemented? TANDBERG: POLYCOM: So, jump to the conclusion: As UAC, identify yourself in User-Agent field. As UAS, identify yourself in Server field. Comparing with TANDBERG and POLYCOM’s implementation, TANDBERG format is more proper.
Vendor ID, Product ID information in SIP
RTP/RTCP入门 Getting started with RTP/RTCP [gview file=”getting-started-with-rtp-rtcp.pdf” save=”0″]
Getting started with RTP/RTCP – RTP/RTCP入门
常见视频通信协议介绍 – GB28181 Video-communication-protocols-GB28181 It’s not a world-wide standard, but a Chinese-marketing-only standard, which was drafted by a number of Chinese government facilities. P.S. It’s a Chinese version of presentation. [gview file=”Video-communication-protocols-GB28181.pdf” save=”0″]
Common video communication protocol intro – GB28181
常见视频通信协议介绍 – RTSP.pdf, Common video communication protocol intro – RTSP P.S. It’s a Chinese version. [gview file=”Video-communication-protocols-RTSP.pdf” save=”0″]
Common video communication protocol intro – RTSP
Common video communication protocol intro – ONVIF 常见视频通信协议介绍 – ONVIF P.S. It’s a Chinese version. 这是一个中文版 [gview file=”http://rg4.net/p/training/Video-communication-protocols-ONVIF.ppt” save=”0″]
Common video communication protocol intro – ONVIF
I like this words: “There’s never a perfect time for anything—you just have go for it and keep your eyes on your goal.” Written by Anne Kreamer August 25, 2015 In the US, where only 11% of working engineers are women and fewer than 5% of the CEOs of the […]
This CEO says her riskiest career move was becoming an ...
This post’s goal is to guide a starter to analysis a crash by reading into the assemble code. But the example listed here is not a good one, because the crash point is not an obvious one, the real reason of the crash for this example is still remain uncovered. […]
Trouble shooting: step by step to analysis crashes
An issue of call establishment delay when conferencing with Polycom MCU RMX2000 The situation was 1. Meeting entities 1). Polycom MCU: Polycom RMX 2000, version ID: 8.3.0 2). Kedacom HD3 H600 SP4 2. Call scenario HD3 joined a multi-point conference with RMX2000. 1) All the H.225 and H.245 processes were […]
A common bug of HD3 series terminals
Most of the missing features are AVPF related, which is defined in RFC4585 and RFC5104. RFC4585: Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF) https://www.rfc-editor.org/rfc/rfc4585.txt RFC5104: Codec Control Messages in the RTP Audio-Visual Profile with Feedback (AVPF) https://www.rfc-editor.org/rfc/rfc5104.txt AVPF contains a mechanism for conveying such a message, […]
RTCP and AVPF related missing features
Found some features were missing after upgraded my blog to the latest version, WordPress v4.0, such as blogrolls. Tried to find it all over the dashboard, but got no luck. So I turned to the almighty Google, finally got the solution, and it’s really easy. All you need to do […]
Restore blogroll function for your WordPress
2 [20150822 Update] For the record, I didn’t find the right ITU-REC document when I wrote this post, and misguided by a claim of HUAWEI VP9650 which says it has AES256 supported, but when I sending out a call from VP9650, it showed a new DH group DH1536, so I made […]
About H.235 encryption algorithms
Encountered an issue of extreme long time compiling days ago, so we tried to add a time cost output in the Makefile to locate what on earth happened during the compilation. There are two Makefiles need to be modified, one is Linux based Makefile, another is Android based Makefile Linux […]
Add compilation time cost for each source file in make ...
Last weekend, from May 15 to May 17, I took a train to Hefei along with more than thirty classmates, to attend the desertation defence, the final phase of the postgraduate study. Those were really busy days for all of us, there were so much forms and paper works for […]
Finished my studies in USTC
Working on a Loongson(www.loongson.cn) PC, goal is to make it a Meeting Terminal. Because its CPU is MIPS arch, there could be lots of unexpected problems, so the first thought hit us is WebRTC. This post is the first step to research into this topic.