Help. How to evaluate a Mp3's quality? Like noise existed in the f Options

[MaiTiano]

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.

[halb27]

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.

[MaiTiano]

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.

[saratoga]

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

[Nessuno]

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

[MaiTiano]

Yes，I do think that there is a evaluation rule for the music quality. not only the bitrates can be used to evaluate it(actually bitrates can not be viewed as the accurate quality rule neither:) )

This post has been edited by db1989: Apr 17 2012, 15:21

Reason for edit: as in post #5

[Nessuno]

Yes，I do think that there is a evaluation rule for the music quality. not only the bitrates can be used to evaluate it(actually bitrates can not be viewed as the accurate quality rule neither:) )

Well, if they are VBR and they have been encoded by the same encoder with the same settings and they all contain similar musical "patterns" (e.g. all symphonic, all piano, all chamber) then actual bitrate might be a very rough estimate of content quality.

Of course "quality" sic et simpliciter is really a very vague criterion....

[MaiTiano]

For the simplicity, for the 1st step, at least I want to detect the noise existed in the music which affect the whole listening experience. Any advices?

This post has been edited by db1989: Apr 17 2012, 15:21

Reason for edit: as in post #8

[knutinh]

For the simplicity, for the 1st step, at least I want to detect the noise existed in the music which affect the whole listening experience. Any advices?

I would claim that I have several recordings with excessive noise that are still subjectively important to me - and examples of low-noise material that is worthless to me.

Sounds to me like trying to detect "good art" automatically. It is going to be hard as long as we dont even have an agreement on what is "good art".

-h