helix mobile producer on-demand user's guide - RealPlayer

Helix Mobile Producer On-Demand User’s Guidehas a maximum bandwidth of 900 Kbps, for example. So during a high-actionscene, for example, a video encoded with this audience may have a bandwidthspike of up to 900 Kbps. These spikes are only occasional, however, and theoverall clip playback rate stays close to the average bit rate.Although you can set the maximum bit rate value higher or lower, a highersetting is unlikely to result in significantly greater quality. You can lower thesetting if you want to reduce the bandwidth spikes on your network. Keep inmind, however, that lowering this maximum decreases the benefit of VBRencoding. The closer the maximum bit rate value approaches the average bitrate value, the more the clip behaves like a CBR clip.Tip: Keep the maximum bit rate value between 50 percent to100 percent greater than the average bit rate setting. For a 450Kbps template, for example, the maximum rate should be 675to 900 Kbps.The leaky bucket algorithmBoth CBR and VBR are consistent with the “leaky bucket” concept. Leakybucket is a flow-control mechanism designed to reduce the effect of theinevitable variability in input data streams as they are “injected” intocommunication networks. The leaky bucket algorithm performs the followingfunctions:• It controls what the encoder can inject into the network.• It prevents the data “bucket” from overflowing by automaticallyregulating the bit rates in the event that the encoder generates too muchdata or very complex data.• It prevents “burstiness” in the input stream, ensuring a smooth, even dataflow.32