摘要
为实现话音无阻塞、视频图像清晰流畅且低延迟的可视通话,提出使用PSTN单独传送话音,使用IP网络单独传送通话者视频并在终端同步还原的方法及其DSP实现的要点,终端以PSTN的拨号呼叫信号或来电振铃信号作为视频呼叫的触发信号,并将其捕获封装为SIP的Invite消息发起呼叫以建立视频P2P连接,使用UDP报文传送RTP视频流。测试表明系统在带宽为256Kbit/s且IP网络无拥塞的条件下,视频实现了CIF分辨力,帧频30f/s(帧/秒),视频延迟小于60ms,通话话音无阻塞,且话音通信与任何现有话音终端兼容,用户使用习惯如电话号码和拨号方式则不需任何改变。
A video phone system which integrates the advantages of PSTN and IP network and its implementation method is proposed. The system consists of terminals and supporting servers. Separately, the voice is transmitted over PSTN and the video image is sent over Internet and they are restored simultaneously in the terminal to achieve calls of non-blocking voice, clear and smooth and low-latency video images. And its voice communication is compatible with any existing voice terminals. The terminal captures and put the dial-up signaling or ringing signaling package as the invite message of SIP for peer-to-peer connection of terminals. And the system uses UDP packets to send the RTP video stream. With non-blocking voice, video delay is less than 60 ms under the conditions of bandwidth at 256 Kbit/s, IP network without congestion,caller videos for CIF resolution and its frame rate is 30 f/s. Moreover, the terminal phone number and the mode of dial-up are the same as PSTN. Its comprehensive performance is better than PSTN video phone or IP video phone.
出处
《电视技术》
北大核心
2009年第8期57-60,108,共5页
Video Engineering
基金
广东省科技计划项目(2007B080701005)
关键词
可视电话
二网融合
无阻塞
低延迟
video phone
PSTN and Internet integration
non-blocking
low-delay
