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=Quality=
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{{stub}}
  
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==Simple==
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This is a list of ''Frequently Asked Questions''. The questions are grouped according to their categories, then sorted alphabetically.
  
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* What do I need to get started?
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Please note that this FAQ provides very short answers; explore the links to get deeper information.
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* What is transparency/cd-quality?
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* What are the best formats?
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* How do you tell what is the best format?
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: See [[Audio format guide]]
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* What is [[ABX]]?
 
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* Why is [[ABX]] needed?
 
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* [[Transcoding]] - Can I increase quality by converting X lossy compressed file to Y lossy compressed file?
 
  
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==Advanced==
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=General Hydrogenaudio Etiquette=
  
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* Can I use [[frequency analysis]] or other tools to judge quality?
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;Why do you stress blind listening / [[ABX]] tests so much?
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* What are good test procedures?
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;Why [http://www.hydrogenaudio.org/forums/index.php?showtopic=3974 TOS #8]?
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:'''Short Answer:''' The usual "audiophile" speak of non-audio related terms which are completely subjective and open to redefinition on a whim, are useless for any sort of progression in discussion.
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:For more detailed and thoughtful answers, see the description of [[TOS 8]] on this wiki or [http://www.hydrogenaudio.org/forums/index.php?showtopic=11442 this forum discussion.]
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=General Audio Compression=
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;Can I increase quality by converting a lossy compressed file to a higher-bitrate lossy compressed file?
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:'''Short Answer:''' This is called [[Transcoding]], and the answer is '''no'''.
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;Does encoding preserve surround info?
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:'''Short Answer:''' Depends. Normal MP3 encoding destroys surround sound information. Go see the page on [[lossy]] encoding.
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:In addition, check the following links:
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:* [http://www.hydrogenaudio.org/forums/index.php?act=ST&f=15&t=4639 Experience of a HA Member with Rear Channel] on the HA Forums
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;What is the best audio format?
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:'''Short Answer:''' Depends on your needs.
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:For a detailed explanation, see [[Audio format guide]].
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;Why do encoded files get clipped when the original WAVs are not clipped?
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:'''Short answer:'''
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:#Quantization errors may cause the signal to clip, and
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:#Gibbs phenomenon through the limitation of bandwidth may cause the signal to clip.
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:Check the following links for more details:
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:* [http://ff123.net/norm.html Explanation on ff123's site]
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;What is an ABX blind test?
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:Go see [[ABX]]
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:In addition, check the following links:
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:* [http://www.hydrogenaudio.org/forums/index.php?showtopic=16295& Blind Listening Test Explanation] on the HA Forums
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;What is "transparency"?
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:Go see [[transparency]]
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;Why not use graphs / frequency analysis to compare codecs?
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:Nothing can be said about quality or audible difference by looking at pictures, because a [[lossy]] encoder works by removing as much inaudible sounds as possible. A lack of frequencies can well mean that some audible parts are missing (bad work, or too low setting), or that the encoder managed a very good compression, removing a lot of useless things.
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:In addition, check the following links:
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:* [[lossy|Lossy]] encoding
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:* [[lossless|Lossless]] encoding
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:* [[frequency analysis]]
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:* [http://www.hydrogenaudio.org/forums/index.php?showtopic=7834&st=0&p=77265&#entry77265 Confusion on CBR & VBR thread] on the HA Forums
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:* ... and [http://www.hydrogenaudio.org/forums/index.php?showtopic=42646&hl= this thread] for a more sarcastic discussion.
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;Is there a way to filter or remove artifacts from poorly-compressed audio?
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:Unfortunately, not at this time. While it is true that compressed video can often use filtering or [[post processing]] during playback to improve image quality, the same cannot be said for audio. Video can be smoothed out, but audio cannot. There is also no data that can be recovered from the compressed audio--the artifacts are present because the original data isn't there anymore!
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:The following Hydrogenaudio thread has more information: [http://www.hydrogenaudio.org/index.php?showtopic=6729 MP3 Post Processing]
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=MP3-related=
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;What is MP3Gain? How do I use it? Is it the same as ReplayGain, but for MP3 only?
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:Go check [[MP3Gain|this page]].
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;Why is joint stereo better than pure stereo ?
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:You better [http://www.hydrogenaudio.org/forums/index.php?act=ST&f=15&t=683 start from this HA thread]
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=CD-Drives=
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;How do I test my drive's C2 accuracy?
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:Visit [http://www.exactaudiocopy.de/eac13.html this page].
 +
 
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 +
 
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[[Category:Guides]]

Latest revision as of 23:04, 1 March 2012

This article is a stub. You can help the Hydrogenaudio Knowledgebase by expanding it.

This is a list of Frequently Asked Questions. The questions are grouped according to their categories, then sorted alphabetically.

Please note that this FAQ provides very short answers; explore the links to get deeper information.


General Hydrogenaudio Etiquette

Why do you stress blind listening / ABX tests so much?
Why TOS #8?
Short Answer: The usual "audiophile" speak of non-audio related terms which are completely subjective and open to redefinition on a whim, are useless for any sort of progression in discussion.
For more detailed and thoughtful answers, see the description of TOS 8 on this wiki or this forum discussion.

General Audio Compression

Can I increase quality by converting a lossy compressed file to a higher-bitrate lossy compressed file?
Short Answer: This is called Transcoding, and the answer is no.


Does encoding preserve surround info?
Short Answer: Depends. Normal MP3 encoding destroys surround sound information. Go see the page on lossy encoding.
In addition, check the following links:


What is the best audio format?
Short Answer: Depends on your needs.
For a detailed explanation, see Audio format guide.


Why do encoded files get clipped when the original WAVs are not clipped?
Short answer:
  1. Quantization errors may cause the signal to clip, and
  2. Gibbs phenomenon through the limitation of bandwidth may cause the signal to clip.
Check the following links for more details:


What is an ABX blind test?
Go see ABX
In addition, check the following links:


What is "transparency"?
Go see transparency


Why not use graphs / frequency analysis to compare codecs?
Nothing can be said about quality or audible difference by looking at pictures, because a lossy encoder works by removing as much inaudible sounds as possible. A lack of frequencies can well mean that some audible parts are missing (bad work, or too low setting), or that the encoder managed a very good compression, removing a lot of useless things.
In addition, check the following links:


Is there a way to filter or remove artifacts from poorly-compressed audio?
Unfortunately, not at this time. While it is true that compressed video can often use filtering or post processing during playback to improve image quality, the same cannot be said for audio. Video can be smoothed out, but audio cannot. There is also no data that can be recovered from the compressed audio--the artifacts are present because the original data isn't there anymore!
The following Hydrogenaudio thread has more information: MP3 Post Processing

MP3-related

What is MP3Gain? How do I use it? Is it the same as ReplayGain, but for MP3 only?
Go check this page.


Why is joint stereo better than pure stereo ?
You better start from this HA thread


CD-Drives

How do I test my drive's C2 accuracy?
Visit this page.
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