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A compression artifact (or artefact) is a noticeable distortion of media (including images, audio, and video) caused by the application of lossy compression. Lossy data compression involves discarding some of the media's data so that it becomes small enough to be stored within the desired disk space or transmitted ( streamed ) within the ...
The data compression software for encoding into ALAC files, Apple Lossless Encoder, was introduced into the Mac OS X Core Audio framework on April 28, 2004, together with the QuickTime 6.5.1 update, thus making it available in iTunes since version 4.5 and above, and its replacement, the Music application. [8]
Generation loss was a major consideration in complex analog audio and video editing, where multi-layered edits were often created by making intermediate mixes which were then "bounced down" back onto tape. Careful planning was required to minimize generation loss, and the resulting noise and poor frequency response.
These errors are termed artifacts (or sound/sonic artifacts), and may be pleasing or displeasing. A sonic artifact is sometimes a type of digital artifact , and in some cases is the result of data compression (not to be confused with dynamic range compression , which also may create sonic artifacts).
In digital signal processing, spatial anti-aliasing is a technique for minimizing the distortion artifacts when representing a high-resolution image at a lower resolution. Anti-aliasing is used in digital photography , computer graphics , digital audio , and many other applications.
A common formula to calculate the audio's energy is = = (()), where is the energy of the signal, is the samples within the audio signal, and () is the th sample's signal amplitude. Once the energy levels are calculated, a threshold is set in which all energy levels that fall below the threshold are considered to be silent and removed.
The compression ratio (that is, the size of the compressed file compared to that of the uncompressed file) of lossy video codecs is nearly always far superior to that of the audio and still-image equivalents. Video can be compressed immensely (e.g., 100:1) with little visible quality loss
On the other hand, if the cause is a band-limited signal, as in JPEG, one cannot simply replace a filter, and ringing artifacts may prove hard to fix – they are present in JPEG 2000 and many audio compression codecs (in the form of pre-echo), as discussed in the examples.