SIP VFU

When a Codec sends out a video frame, it initially will transmit frames described as I frames (reference frames). The I Frame contains the complete information needed to display a picture. To save on bandwidth, instead of continuously transmitting the I frames, a technique is used where the subsequent video packets sent after the I Frame are just updates to the initial picture. These updates which are labeled P Frames are sent to minimize the amount of video data that needs to be transmitted from one video system to another. Occasionally the P Frames become corrupted through different issues such as packet loss, jitter, or there is too much information. At this point the far end would request a Video Fast Update request. The VFU requests a new I Frame be sent with the full reference frame of video information. Once the new I-Frame is sent, the subsequent packets sent will be P-Frames starting with the new I Frame just sent. The VFU feature is always running on the IMG 2020 and cannot be disabled.

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