Lossy: Difference between revisions
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'''Lossy''' compression is a form of compression that takes advantage of | '''Lossy''' compression is a form of compression that significantly reduce multimedia file size by throwing away information imperceptible to humans. | ||
Human audio perception is not perfect. Lossy compression takes advantage of this characteristics. By selective discarding, much unnecessary information is thrown away. The amount of information discarded is usually adjustable, giving a compromise between small size bad quality and high quality large size. | |||
The downside to this is that waveform reconstructed from compressed information will never exactly match the original waveform. | |||
==Does Lossy Encoding Preserve Surround Information?== | ==Does Lossy Encoding Preserve Surround Information?== | ||
Depending on the encoder and settings, degradation of surround imaging may happen. Use higher [[bitrate]]. Mid/Side stereo of [[LAME]] or [[AAC]] does not destroy surround information. Also [[MPC]] preserves surround information with standard settings reasonably well. The lower the [[bitrate]], the worse you can expect the surround imaging become. | Depending on the encoder and settings, degradation of surround imaging may happen. Use higher [[bitrate]] to prevent this from happening. Mid/Side stereo of [[LAME]] or [[AAC]] does not destroy surround information. Also [[MPC]] preserves surround information with standard settings reasonably well. The lower the [[bitrate]], the worse you can expect the surround imaging become. | ||
* [http://www.hydrogenaudio.org/forums/index.php?act=ST&f=15&t=4639 More discussion] | * [http://www.hydrogenaudio.org/forums/index.php?act=ST&f=15&t=4639 More discussion] | ||
==List of common lossy formats== | ==List of common lossy formats== | ||
* [[AAC]] (also improperly known as [[MP4]] or [[M4A]]) | * [[AAC]] (also improperly known as [[MP4]] or [[M4A]]) | ||
* [[AC3]] | * [[AC3]] | ||
* [[ATRAC3]] | |||
* [[DTS]] | * [[DTS]] | ||
* [[ | * [[MP2]] | ||
* [[MP3]] | |||
* [[Musepack]] (also known as [[MPC]], formerly known as [[MPEGplus]] or MP+) | |||
* [[Ogg Vorbis]] | |||
* [[QDesign]] | * [[QDesign]] | ||
* [[Speex]] (speech only) | |||
* [[VQF]] | * [[VQF]] | ||
* [[ | * [[WMA]] | ||
==See Also== | ==See Also== | ||
* [[Lossless]] | * [[Lossless]] | ||
Revision as of 13:33, 5 January 2006
Lossy compression is a form of compression that significantly reduce multimedia file size by throwing away information imperceptible to humans.
Human audio perception is not perfect. Lossy compression takes advantage of this characteristics. By selective discarding, much unnecessary information is thrown away. The amount of information discarded is usually adjustable, giving a compromise between small size bad quality and high quality large size.
The downside to this is that waveform reconstructed from compressed information will never exactly match the original waveform.
Does Lossy Encoding Preserve Surround Information?
Depending on the encoder and settings, degradation of surround imaging may happen. Use higher bitrate to prevent this from happening. Mid/Side stereo of LAME or AAC does not destroy surround information. Also MPC preserves surround information with standard settings reasonably well. The lower the bitrate, the worse you can expect the surround imaging become.
List of common lossy formats
- AAC (also improperly known as MP4 or M4A)
- AC3
- ATRAC3
- DTS
- MP2
- MP3
- Musepack (also known as MPC, formerly known as MPEGplus or MP+)
- Ogg Vorbis
- QDesign
- Speex (speech only)
- VQF
- WMA