Autodesk 64006-051108-9001 User Guide - Page 88

80 Chapter 6: Pre-processing Dynamic Range The Dynamic Range of an audio track is the difference in volume between the quiet and loud parts of the signal. For example, classical music often has a wide dynamic range. Quiet passages may be a single unaccompanied violin, but loud passages may be the entire orchestra playing at once. Rock music, on the other hand, often has a fairly limited dynamic range. Even though the music is loud, the bass, guitars and drums are usually played constantly, so there is not that much difference between the quiet and loud parts. The Dynamic Range filter enables you to boost the volume of quiet parts of the audio, while limiting loud parts. This is similar to the Normalize feature, but the audio is adjusted on a section-by-section basis instead of by a single factor for the whole file. Narrowing the dynamic range of your material can make your audio effectively sound louder even if the highest points are still at the same level. This is because quieter passages are selectively boosted while the loud sections are not significantly altered. Changing the dynamic range is often useful for Web audio because some low bandwidth codecs do not handle material that is too loud or too soft. Compressing the dynamic range of the material enables you to keep the loudest sections within acceptable limits, which also effectively raises the volume of the quiet areas. Dynamic Range Presets Cleaner has three Dynamic Range filter presets: •Limit to 90% - ensures the peak of the audio never exceeds 90% of volume. This is important for compressed Web audio because many codecs do not work well with material above this level. •Hotter - increases the apparent volume of the audio without making the peaks any higher. It increases the volume of the quieter sections, which works well when you want to make your movies sound louder without distortion. However, because this option does not limit the peaks to 90%, you may have better results using the Narrow Range option for Web audio. •Narrow Range - limits the peak volume to 90% and brings the bottom up to 20%. This has the effect of slightly increasing the apparent volume, while still limiting the audio for compressed Web distribution. For the best results, use either the Narrow Range or Limit to 90% setting with Web audio. With these options, you do not need to normalize the audio to 90% because this filter already limits the peaks to this value. Start with a value of about 40, then increase or decrease this number as needed to minimize the obviousness of the transitions.