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

Chapter 6:SETTING ENCODING PARAMETERSCHAPTER6This chapter provides detailed descriptions of audio and videoencoding parameters and options.Setting Job ParametersWhen encoding a media, you can define job-specific parameters: you canspecify the track you want to encode (audio and/or), the bit rate control(variable or constant bit rate) and the number of encoding passes.Audio/video encodingIf the input source contains both audio and video tracks, you can indicate thetrack you want to encode by selecting the corresponding option button, asshown in the following illustration.Controls for Selecting TracksBit rate controlEach audience is either constant bit rate (CBR) or variable bit rate (VBR). TheCBR audiences are designed for streaming. When you use them, you canencode multiple audiences into a clip or broadcast. For example, a single clipcan stream to 56 Kbps modems and faster broadband connections when youuse CBR encoding.The VBR audiences are designed for downloadable clips, but can also be usedfor streaming in some instances. When you encode a downloadable clip, youselect a VBR template according to how highly you want to compress theinput, or how well you want to preserve the input’s quality. Unlike CBR clipsthat can have multiple audiences, VBR clips can include just one audience.29