• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Audio issues

Audio issues

In digital audio, vibrations in the air (or electrical impulses traveling down a wire) are converted to a string of numbers that a computer can store and replay at a later time. This is done by sampling the air pressure or signal level at regular intervals. The frequency of these intervals is known as the sample rate; it is similar to the concept of pixels and dots per inch in a digitized image. Each sample is converted into a number. The precision of these numbers is usually 8 or 16 bits per sample; this is known as a sample's resolution or bit depth. The concept is similar to one in graphics—the more samples and bits you have, the more accurate the sound.

Audio resolution

Every bit of resolution in an audio file closely corresponds to 6 decibels (dB) of signal level, with the decibel being the common unit used to measure audio loudness. Older systems had 8-bit audio resolution. This translates roughly into a 48 dB signal-to-noise ratio, which isn't very high—roughly the equivalent of noisy AM radio. Newer systems use 16-bit resolution, which translates roughly to a 96 dB signal-to-noise ratio. This is the same as used by audio CDs, and is very good. The Audio Level palette in Adobe After Effects displays audio level as both decibels and percentage of full scale. Adobe After Effects performs linear fades in units of decibels, not percentage.


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint