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Topic: Frequency content of MP3 files (Read 5482 times) previous topic - next topic
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Frequency content of MP3 files

I have a huge collection of Old Time Radio (OTR) shows. They are all MP3 files. I did not encode any of them, so I had no control of how they were encoded. Most are quite listenable, but some are terrible.

I just found one particular file that was not only encoded at a low bitrate (32Kb), but sounded much worse than it should have. Looking at it with a VST spectrum analyzer plugin, I saw that it contained no audio frequencies over 2KHz (none!). This is why it sounded so muffled and muddy.

This brings me to my question. Is there any software (freeware/shareware) that will check a batch of MP3 files for this type of defect? Even just a notation of the lowest and highest frequencies in each file (or even the first several minutes) would be helpful. I have so many files that trying to weed things out by listening to each one would take a lifetime. If there were such a program, I could just run it overnight on selected batches of files.

Any suggestions?

Thanks.

Frequency content of MP3 files

Reply #1 –
Quote from: Mojoe on
This brings me to my question. Is there any software (freeware/shareware) that will check a batch of MP3 files for this type of defect? Even just a notation of the lowest and highest frequencies in each file (or even the first several minutes) would be helpful. I have so many files that trying to weed things out by listening to each one would take a lifetime. If there were such a program, I could just run it overnight on selected batches of files.

Any suggestions?

Thanks.

You could try Encspot, an MP3 analyser that, besides other useful information like bitrate, encoder and encoding mode, displays the lowpass value that was used, but only if it is stored in the LAME tag, i.e. usually only with newer versions of the LAME MP3 encoder.
Proverb for Paranoids: "If they can get you asking the wrong questions, they don't have to worry about answers."
-T. Pynchon (Gravity's Rainbow)

Frequency content of MP3 files

Reply #2 –
Quote from: sTisTi on
You could try Encspot, an MP3 analyser that, besides other useful information like bitrate, encoder and encoding mode, displays the lowpass value that was used, but only if it is stored in the LAME tag, i.e. usually only with newer versions of the LAME MP3 encoder.

  where do you see the lowpass?? I tried "encspotting" a LAME 3.97b2 mp3 and cant find the lowpass

Frequency content of MP3 files

Reply #3 –
just right click on the bar with name, encoder, bitrate etc...then click costumize, and then you have to find lowpass somewhere in there. Then you can select it and it will appear in the 'normal' screen.

Frequency content of MP3 files

Reply #4 –
Quote
You could try Encspot, an MP3 analyser that, besides other useful information like bitrate, encoder and encoding mode, displays the lowpass value that was used, but only if it is stored in the LAME tag, i.e. usually only with newer versions of the LAME MP3 encoder.


Thanks for the suggestion. I use Encspot, but didn't see that column before. However, on almost all of these MP3 files that column says "Unknown". I think I really need a program that I can drop a group of files into and have it actually look at the frequency content of each file. Even a fast scan to tell me the highest frequency in each file would be helpful.

Frequency content of MP3 files

Reply #5 –
Quote from: hxkclan on
just right click on the bar with name, encoder, bitrate etc...then click costumize, and then you have to find lowpass somewhere in there. Then you can select it and it will appear in the 'normal' screen.

ok, so then it looks like I have some bad Encspot version, because when I right-click where you said, nothing happens...

J.M.

Frequency content of MP3 files

Reply #6 –
Are you using the free or pro version? Perhaps thats why you can't see all the options?

Kristian

Frequency content of MP3 files

Reply #7 –
Quote from: kritip on
Are you using the free or pro version? Perhaps thats why you can't see all the options?

Kristian

I'm using the free version.. but I think it should be able to read the Lame tag?

Mojoe, do you also have the Pro version that you can see the lowpass column?  eh, you all are using the Pro version ...??

J.M.

Frequency content of MP3 files

Reply #8 –
Quote from: jmartis on
Quote from: kritip on

Are you using the free or pro version? Perhaps thats why you can't see all the options?

Kristian

I'm using the free version.. but I think it should be able to read the Lame tag?

Mojoe, do you also have the Pro version that you can see the lowpass column?  eh, you all are using the Pro version ...??

J.M.

It's available both in the free and pro version.
Go to options > settings > Lame tag > mark the column that says "lowpass filter"
Proverb for Paranoids: "If they can get you asking the wrong questions, they don't have to worry about answers."
-T. Pynchon (Gravity's Rainbow)

Frequency content of MP3 files

Reply #9 –
Quote from: sTisTi on
Go to options > settings > Lame tag > mark the column that says "lowpass filter"

I tick the lowpass filter column.. I encode a file w/ lame3.97b2.. I open it in encspot.. no lowpass information 

(edit -little typo in lame ver.)

Frequency content of MP3 files

Reply #10 –
Quote from: jmartis on
Quote from: sTisTi on

Go to options > settings > Lame tag > mark the column that says "lowpass filter"

I tick the lowpass filter column.. I encode a file w/ lame3.97b2.. I open it in encspot.. no lowpass information 

(edit -little typo in lame ver.)

I just tested it with a fresh install of Encspot basic 2.0 build 817, and it works just as I described it. After selecting "lowpass filter", a new column is created in the main window which shows this information. I've no idea what goes wrong with your setup. Does your version not show any additional columns when you select them in the options?
Proverb for Paranoids: "If they can get you asking the wrong questions, they don't have to worry about answers."
-T. Pynchon (Gravity's Rainbow)

Frequency content of MP3 files

Reply #11 –
Although I appreciated the suggestion to try Encspot, it seems that my thread has wandered off topic. I'm still looking for suggestions on my original question. What would be ideal would be a command line program that could take an MP3, analyse it and tell me the higest/lowest frequency in the file, ignoring everything below a specified signal level (let's say -60dB for example). With something like that, I could process a batch of files at a time, save the results and weed out the bad files later.
 

Frequency content of MP3 files

Reply #12 –
I doubt something like that exists since your problem is so specific.