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

CHAPTER 3: Quick StartJobsThe job defines how to encode your clip. It selects the media inputs, sets theencoding properties, and defines the destinations, such as whether to save theencoded stream to a clip, forward it to a server for broadcast, or both.For More Information: Chapter 5 explains how to define jobsthrough the graphical application. See Chapter 7 forinformation about specifying jobs on the command line.Appendix B explains the job file syntax.AudiencesEncodingWhen you set up a job, you choose one or more audiences. An audiencedefines several aspects of the encoding job. Most importantly, it defines thebit rate at which a clip or broadcast streams. For a downloadable clip, theaudience selection affects the clip’s quality and file size. Selecting an audienceis therefore one of the most important decisions you make when encoding aclip. Helix Mobile Producer On-Demand predefines a number of audiencesdesigned to fit a variety of streaming and downloading requirements.For More Information: Chapter 4 explains how to selectaudiences through the graphical application. Chapter 7 doesthe same for the command-line application. You can alsocreate your own audiences, as explained in Appendix A.Encoding compresses digital media so that it takes up less space and can betransmitted faster. The compression process identifies the essentialcomponents of the input media and discards the superfluous parts.Be aware that the addition of data such as hint tracks and headers to audio orvideo streams during the encoding process results in the encoded files beingsomewhat larger than the sum of the encoded media bit rates multiplied bythe duration of the file ((audio bit rate + video bit rate) x duration). This doesnot affect the bit rate or quality of the media, because this additional dataremains on the server and is not streamed to the client.Note: The hint track is required by the streaming server tooptimize the streaming experience. A 3GPP media file musthave a hint track to be properly streamed from most streamingservers. The hint track is not required if the media file is to bedownloaded and played locally, however. To avoid having Helix13