Scalable voip mobility intedration and deployment- P37: The term voice mobility can mean a number of different things to different people. Two words that can be quite trendy by themselves, but stuck together as if forgotten at a bus station long past the last ride of the night, the phrase rings a number of different, and at times discordant, bells. | The Future Video Mobility and Beyond 361 used for example to synchronize the one or more audio channels with the one video channel. On the other hand encoded video itself usually comes with its own frame encapsulation mechanism. The reason for this is that it allows all of the media streams for a video to be kept together. These mechanism allow the embedding of the audio streams into the video stream even on a real-time basis and thus provides a higher-layer representation of the order and flow of the video on top of RTP. Whether the audio streams are combined into the video is as much a function of the device that is sending the video and the signaling application as it is the video encoding. Because all of the media can be kept together in one stream of bytes TCP-based streaming for video also works. The disadvantage of using TCP of course is that the real-time nature of the stream is broken as TCP will delay the stream if not every byte can make it through at the moment. On the other hand TCP-based video streaming is the popular method of transporting video over the Internet especially when having real-time video is not the requirement and approximately real-time video is acceptable. This is commonly used for news streaming where the content needs to be almost live but it is acceptable for different viewers to see versions of the video with different delays based on whatever the transport required. Nevertheless it is important to maintain a distinction between serving video clips and streaming live video. Both may use TCP but the latter will be rate-limited to the speed of the real-time video and thus special quality-of-service considerations can be applied that might not be appropriate for the former. Video Signaling Video signaling depends on the application being used to send the video. However the requirements for effective video conferencing share a great deal with that of voice calling and so the concepts learned in previous chapters can be .
