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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


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


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