TITLE
    QuickTime: Movie Player Audio Distortion
Article ID:
Created:
Modified: 		16123
8/29/94
1/18/99
TOPIC

    Audio is distorted in QuickTime Movie Player at low volumes. The Volume fader on the Movie Controller does indeed lower the volume of the sound in the movie, but leaves the sound of the aliasing and hiss at the same level, no matter what volume setting is used.

    At lower volume levels, the noise is as loud as the intended program material. This does not seem to happen if you open the same file in SoundEdit 16 or DigiTrax. Lowering the sound playback volume lowers all that is included in the program material, including hiss and anomolies. Is this a problem with Sound Manager 3.0?

DISCUSSION

    All volume in QuickTime is handled by the Sound Manager.

    This is actually normal behavior for Sound Manager 3.0. The loss of sound resolution is due to scaling of the actual sound samples. For 8-bit samples (and especially quiet sounds), there isn't much resolution to begin with (256 levels). The alert volume slider scales each of these samples when sending them to the output channel, causing the distortion.

    In the future, the Sound Manager may apply some sort of non-linear scaling for 8-bit sounds to minimize this problem.

    The work around is to record audio in QuickTime movies to a level that allows comfortable playback while the Movie Player volume control is at its highest level.

Document Information
Product Area: Apple Software
Category: QuickTime
Sub Category: General Topics

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