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Help. How to evaluate a Mp3's quality? Like noise existed in the f
MaiTiano
post Apr 16 2012, 12:00
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As mentioned in the title.

Now I am evolving into a project. In this project, we have a 128kbps mp3 library and we need to find which files have the inferior quality, such as noise existed, volume is too small etc.

Any advice? It would be better if someone know some open-source project which already has the ability to detect the mp3 files with bad quality.

many thanks.
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halb27
post Apr 16 2012, 12:10
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Sounds like you don't have a reference to the original uncompressed music.
If this is true the only thing that can be achieved IMO is looking for issues like temporal smearing with percussion instruments or impulses for electronic music, or other things like unusual tremolo or other effects. But without reference to the original it's often hard to say whether suspected issues are due to mp3 compression or due to an imperfect recording for instance.


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MaiTiano
post Apr 17 2012, 02:35
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QUOTE (halb27 @ Apr 16 2012, 12:10) *
Sounds like you don't have a reference to the original uncompressed music.
If this is true the only thing that can be achieved IMO is looking for issues like temporal smearing with percussion instruments or impulses for electronic music, or other things like unusual tremolo or other effects. But without reference to the original it's often hard to say whether suspected issues are due to mp3 compression or due to an imperfect recording for instance.



Yep, I do not have the reference to the original lossless music.

My goal is to tell whether a mp3 file has a good quality or not just depends on its file only. No matter the bad quality is caused by mp3 compression or imperfect recording, I just need to tell people that it has good quality or not.
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saratoga
post Apr 17 2012, 02:53
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Determining which will sound better to a person is a subjective process, and no one that can be readily done by a machine.

This post has been edited by db1989: Apr 17 2012, 15:20
Reason for edit: removing unnecessary full quote of above post
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Nessuno
post Apr 17 2012, 07:42
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QUOTE (saratoga @ Apr 17 2012, 03:53) *
Determining which will sound better to a person is a subjective process, and no one that can be readily done by a machine.


So what the "quality" setting of every lossy encoder does actually mean?

This post has been edited by Nessuno: Apr 17 2012, 07:44


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pdq
post Apr 17 2012, 13:38
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QUOTE (Nessuno @ Apr 17 2012, 02:42) *
QUOTE (saratoga @ Apr 17 2012, 03:53) *
Determining which will sound better to a person is a subjective process, and no one that can be readily done by a machine.


So what the "quality" setting of every lossy encoder does actually mean?

In this case quality has a very specific meaning - how close the audible result is to the original.
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Nessuno
post Apr 17 2012, 17:38
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QUOTE (pdq @ Apr 17 2012, 14:38) *
QUOTE (Nessuno @ Apr 17 2012, 02:42) *

So what the "quality" setting of every lossy encoder does actually mean?

In this case quality has a very specific meaning - how close the audible result is to the original.


Ok, I'm no expert, but it seems to me that "close to the original" it's not just a matter of analitically measuring the distance between two signals: some assumption of what has more impact in the perceived quality of output are also made, like a larger lowpass on input on higher quality settings (so bandwidth is considered a quality index), clipping prevention (so clipping is considered a low quality index), preserve dynamic, apply weaker masking at certain frequencies and so on...

And in general, to develop a perceptual model, some assumption on which signal characteristics have more influence on its perceived quality should be made, shouldn't they?

This post has been edited by Nessuno: Apr 17 2012, 17:40


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saratoga
post Apr 17 2012, 17:53
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QUOTE (Nessuno @ Apr 17 2012, 12:38) *
And in general, to develop a perceptual model, some assumption on which signal characteristics have more influence on its perceived quality should be made, shouldn't they?


Correct.
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Posts in this topic
- MaiTiano   Help. How to evaluate a Mp3's quality? Like noise existed in the f   Apr 16 2012, 12:00
- - halb27   Sounds like you don't have a reference to the ...   Apr 16 2012, 12:10
|- - MaiTiano   QUOTE (halb27 @ Apr 16 2012, 12:10) Sound...   Apr 17 2012, 02:35
|- - saratoga   Determining which will sound better to a person is...   Apr 17 2012, 02:53
|- - .alexander.   Robot will never replace man © Ogre   Apr 17 2012, 06:36
|- - Nessuno   QUOTE (saratoga @ Apr 17 2012, 03:53) Det...   Apr 17 2012, 07:42
|- - MaiTiano   Yes,I do think that there is a evaluation r...   Apr 17 2012, 08:44
||- - Nessuno   QUOTE (MaiTiano @ Apr 17 2012, 09:44) Yes...   Apr 17 2012, 09:11
||- - MaiTiano   For the simplicity, for the 1st step, at least I w...   Apr 17 2012, 10:01
||- - knutinh   QUOTE (MaiTiano @ Apr 17 2012, 11:01) For...   Apr 18 2012, 11:59
|- - pdq   QUOTE (Nessuno @ Apr 17 2012, 02:42) QUOT...   Apr 17 2012, 13:38
|- - Nessuno   QUOTE (pdq @ Apr 17 2012, 14:38) QUOTE (N...   Apr 17 2012, 17:38
|- - saratoga   QUOTE (Nessuno @ Apr 17 2012, 12:38) And ...   Apr 17 2012, 17:53
- - Nessuno   QUOTE (MaiTiano @ Apr 16 2012, 13:00) Now...   Apr 16 2012, 12:25
- - IgorC   Starting from previous knowledge will be somethin...   Apr 17 2012, 14:28
- - Dynamic   QUOTE (MaiTiano @ Apr 16 2012, 11:00) Any...   Apr 18 2012, 11:51
- - MaiTiano   I would like to add a more specific example to ill...   Apr 18 2012, 12:35
- - Dynamic   You've defined your problem a bit better. You...   Apr 18 2012, 13:22
|- - MaiTiano   QUOTE (Dynamic @ Apr 18 2012, 14:22) You ...   Apr 19 2012, 03:27
|- - saratoga   QUOTE (MaiTiano @ Apr 18 2012, 22:27) I h...   Apr 19 2012, 03:33
|- - MaiTiano   QUOTE (saratoga @ Apr 19 2012, 04:33) Sin...   Apr 19 2012, 03:44
|- - Dynamic   I'd assumed, perhaps wrongly, that you were di...   Apr 19 2012, 20:41
|- - MaiTiano   QUOTE (Dynamic @ Apr 19 2012, 21:41) I...   Apr 20 2012, 04:39
- - Dynamic   [1] - Yes, I think it's the whole song [2] - I...   Apr 25 2012, 20:44
- - MaiTiano   QUOTE (Dynamic @ Apr 25 2012, 21:44) [1] ...   May 22 2012, 02:24


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