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

Helix Mobile Producer On-Demand User’s GuideSampling RateThe Sampling Rate column lists the codec’s optimum sample rate. Using acodec’s optimum sampling rate in your audio source file ensures that theaudio stays synchronized with other media and prevents pitch shifting duringaudio resampling. Audio quality degrades if you use lower than the optimumsampling rate.Audio input should be set at the same sample rate as required by the desiredoutput codec. In the case of SureStream encoding, the input sample rateshould be equal or greater than the largest sample rate of all codecs inincluded in the output.If you use a higher sampling rate when creating the source audio, it is best touse a multiple of the optimum rate. If the optimum rate is 8 kHz, for example,use a higher rate of 16 kHz or 32 kHz. When in doubt, use a CD-qualitysampling rate of 44.1 kHz for your source audio.Frequency ResponseA codec with a higher frequency response reproduces a wider range of soundthan a codec with a lower response. High Response is indicated after the codernameFrequency response measures how much of the original audio’s frequencyrange will be used in creating the RealAudio clip. Thus, the codec does notenhance produced audio’s quality; it always results in a clip of equal or lowerquality than the original audio. For example, if the original audio has an 8kHz frequency response, encoding it with a codec that has a frequencyresponse of 10 kHz produces a clip that still has a response of 8 kHz.For More Information: The audio preparation chapter ofRealNetworks Production Guide has an expanded list that coversall RealAudio codecs, including obsolete codecs no longer usedby Helix Producer.CompatibilitySome codecs are available for use with early versions of the RealPlayer.Compatibility is indicated below each codec type.84