How fast is changing channels (channel-surfing)?

This varies depending on the channel, as these are supplied from different sources. With unicast the channel change normally takes less than a second, with multicast it takes a little longer. This is due to the fact that with multicast the system always waits for the next available intra-frame. Unicast uses the last available intra-frame, which makes channel switching faster, but live broadcasts will be delayed. However, with multicast, the more people that watch TV7 at the same time in your area, the faster the channels change because the multicast streams in your area already exist.