1 Principles of video coding
1.1 An image or a video sequence is compressed to generate a stream of code.
Image processing is: Intra-frame predictive coding
The predicted value p, which is obtained by motion compensation, is referenced by the
layer or storage media, and provides early information to provide video encoding and external world interfaces.
NALU: defines basic formats that can be used for group-based and bit stream-based systems.
RTP encapsulation: only for the local nal Interface Based on the nal unit.
Three different data forms:
Sodb data Bit String --> the original encoding data
Rbsp original byte sequence load --> after sodb, add the ending bit (rbsp trailing bits is a bi
Real-time transfer implementation based on the jrtplib library in Linux
I. RTP is a standard protocol and Key Technology for Real-Time Streaming Media transmission.
Real-Time Transport Protocol (PRT) is a network protocol used to process multimedia data streams over the Internet. It can be used in one-to-one (unicast, unicast) scenarios) or you can transmit streaming media data in real time in a one-to-multiple (Multi-play) network environment.
http://blog.csdn.net/noiile/article/details/115436
What are the problems with SIP from private network to public network?
Address translation of the package.
SIP address Translation inside the SIP message.
The RTP address translation in the SDP inside the SIP message.
The existing structure of the network is complex, SIP service providers are not necessarily network providers, it is difficult to ask customers to use only some way of natfirewall. Ho
) protocol is a connection-oriented transport protocol, the communication needs to establish a connection, transmission delay is large, TCP recognition and retransmission mechanism, flow control mechanism can ensure reliable data transmission, but the processing process is complex and inefficient, for audio and video streaming , frequent acknowledgement and retransmission cannot guarantee the real-time transmission of data, so it is relatively unsuitable for the transmission of video images.
Su
The original link (also reproduced) http://blog.csdn.net/yetyongjin/article/details/6881491. I have modified some typos. SIPWhat kind of problems do you encounter from the private network to the public network? 1. Address translation of the package.2. SIP address translation inside SIP messages.3. The RTP address translation in the SDP in the SIP message.The existing structure of the network is complex, SIP service providers are not necessarily networ
Use DirectShow to implement QQ's audio/video chat function
Currently, popular instant messaging tools, such as MSN and QQ, all implement the video and audio functions. Through video and audio, we can better communicate with our friends through the network, this article uses DirectShow technology to simulate QQ to achieve video and audio acquisition, transmission, and basically implement the QQ video and audio chat function.
The main function of the network video/audio system is the collection of
generation of video coding standards jointly developed by a Joint Video group (JVT) consisting of the ITU-T video coding Expert Group (VCEG) and the ISO/IEC dynamic image Expert Group (mPEG, its biggest advantage is its high data compression ratio. h. 264 of the compression ratio is more than 2 times of the MPEG-2, is the MPEG-4 of 1.5 ~ 2 times. At the same time, the layer design of the video encoding layer (VCL) and network extraction layer (NAL) is very suitable for real-time transmission of
016-11-25 DORAWEBRTC series Wind net WEBRTC series Wind Net
Source: Wind NET Series
Author: Weizhenwei, fan network columnist
Audio and video synchronization is the most intuitive user experience for multimedia products, and is the most basic quality guarantee for audio and video media data transmission and rendering playback. If the audio and video is not synchronized, it is possible to cause delay, lag, etc. that affect the user experience very much. Therefore, it is very important. In general
Turn from: http://blog.csdn.net/lixiaowei16/article/details/53407010
Audio and video synchronization is related to the most intuitive user experience of multimedia products, audio and video media data transmission and rendering playback of the most basic quality assurance. If the audio and video is not synchronized, it may cause delays, such as cotton, etc. very affect the user experience phenomenon. Therefore, it is very important. Generally speaking, the audio and video synchronization maint
2016-11-25 DORAWEBRTC series Wind net WEBRTC series Wind Net
Source: Wind NET Series
Author: Weizhenwei, fan network columnist
Audio and video synchronization is the most intuitive user experience for multimedia products, and is the most basic quality guarantee for audio and video media data transmission and rendering playback. If the audio and video is not synchronized, it is possible to cause delay, lag, etc. that affect the user experience very much. Therefore, it is very important. In gener
Section 5. transmitting and receiving media
JMF and real-time transmission protocol (RTP)
Many friendly network features are directly built in JMF, which makes it easy for client programs to transmit and receive media over the network. When a user on a network wants to receive media streams of any type, it does not need to wait for all broadcasts to be downloaded to the machine before watching the media; users can watch broadcasts in real time. This c
Transport Protocol III, RTSP (real Time streaming Protocol)
The above streaming media playback based on progressive downloading can only support on-demand and cannot support live broadcast, the rate at which the media stream data arrives at the client is not precisely controlled, and the client still needs to maintain a buffer storage space of the same size as the media file on the server, waiting for a long buffer time before it can begin playback, resulting in poor real-time performance, Duri
for different NAT types.
L UPnP
L external Query
L stun
L ALG
Among them, the first three are obtained by the SIP client (including UA and proxy) by some means or protocol before the invite. The SIP client is required to provide additional support and is not applicable to all Nat methods.
The ALG (Application Layer Gateway) is applicable to all Nat methods and does not require any additional support from the SIP client. It processes and modifies the sip signaling at the application layer to ach
Implementation of real-time transmission based on Jrtplib library under LinuxRTP is a standard protocol and key technology for real-time streaming media transmission.Real-time transport protocol (real-time transport PROTOCOL,PRT) is a network protocol for processing multimedia data streams on the Internet, which can be used in one-to-one (unicast, unicast) or one-to-many (multicast, multicast), the real-time transmission of Liu Media data is realized in the network environment.
Real-time transmission protocol RTP
1. RTP protocol:RTP (Real-Time Transport Protocol) was originally used in 1970s to try to transfer audio files, divided into several parts to transmit voice, time signs and queue numbers. After a series of developments, the first version of RTP was released by a laboratory in the United States in August 1991. By the 1996 s of t
RTP
Reference rfc3550/rfc3551
Real-Time Transport Protocol) is a transport layer protocol for multimedia data streams on the Internet. The RTP protocol details the standard packet formats for transmitting audio and video on the Internet. RTP is often used in streaming media systems (with RTCP protocol), video conferencing and one-click push to talk systems (with
RTP Reference Document
Rfc3550/rfc3551
Real-Time Transport Protocol) is a transport layer protocol for multimedia data streams on the Internet. The RTP protocol details the standard packet formats for transmitting audio and video on the Internet. RTP is often used in streaming media systems (with RTCP protocol), video conferencing and one-click push to talk syste
This article focuses on the frame capture method and transfers the focus from video4linux to the network. In terms of instant transfer of network images, RTP is also the standard used by major manufacturers. In this phase, we will be able to learn how to use jrtplib
To add network functions.
Video4linux frame capture method
In the last issue of xawtv, we saw the image capture function of xawtv,
Among them, the most important part is to use video4linux
//The Ben function is used to calculate jitter, and this function is called to calculate jitter each time a RTP packet is received. voidRtpreceptionstats::noteincomingpacket (u_int16_t seqNum, u_int32_t rtptimestamp, unsigned Timestampfrequen CY, Boolean Useforjittercalculation,structtimevalResultpresentationtime, Booleanresulthasbeensyncedusingrtcp, unsigned packetsize) { if(!fhaveseeninitialsequencenumber) Initseqnum (seqNum); ++fnumpacketsreceived
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