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Topic: AAC/MP4/M4a Frequency Response (Read 2780 times) previous topic - next topic
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AAC/MP4/M4a Frequency Response

I use Audition to see the cut-off of my mp3 files but would like to do the same with ACC. Is there a way to do this with a (gui) program?.

MODERATION: Changed "Spectrum Analysis" to "Frequency Response" in the topic title.  The OP doesn't appear to be interested in spectral plots.

Re: AAC/MP4/M4a Spectrum Analysis

Reply #1
Spek.


Re: AAC/MP4/M4a Spectrum Analysis

Reply #3
Does that mean Audition can't open AAC files?

If that's the problem you can convert the flies to WAV (which won't change the spectrum).   If you don't have a program to do that, try TAudioConverter or Audacity.

And if you want to compare the MP3 spectrum to the AAC spectrum, you should use the same spectrum analyzer.


P.S.
It's OK if you want to look at and compare the spectrums, but don't fall into the trap of judging audio quality by what you can see or what you can measure.    If you hear compression artifacts, it's usually not the lack of high frequencies that you're hearing, and it's usually not something that's easily measured or "seen"...  


Re: AAC/MP4/M4a Spectrum Analysis

Reply #4
There are generally only two reasons why people do this:
  • as an erroneous attempt to judge quality
  • as an erroneous attempt to look for transcodes

Will this portion of the topic fit into the "other" category or can I drop links to the last two discussions pointing out why this method is useless?

Does that mean Audition can't open AAC files?
There are free filters available which allow Audition to open and save as AAC/mp4 files.  Last I checked they include FAAC, nero and QT and are pretty easy to find on the web.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Re: AAC/MP4/M4a Spectrum Analysis

Reply #5
I was looking for a clean linear frequency analysis like this. This is from a 160 kbps CBR Blade mp3. You'll notice it doesn't cut-off at 15.5 like Fraunhofer or Helix. If I could find a tool like that for AAC, I'd be happy. Why should I have to decode every file I want to examine and compare?.

Re: AAC/MP4/M4a Spectrum Analysis

Reply #6
Why should I have to decode every file I want to examine and compare?.
So you want to "examine and compare" the frequency response* of lossy codecs.

What do you hope to accomplish from this?

(*) perhaps I should change the topic title so that people don't think you want to look at a spectral view(?).
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Re: AAC/MP4/M4a Spectrum Analysis

Reply #7
Maybe he wants to replicate the codec comparison web site I made over 20 years ago, back when I thought certain codecs were irreparably mangling my audio, when the effects were basically what I now know to be the effects of psychoacoustic modeling and frequency masking, which 128kbps WMA seemed to be doing way more severely than anything else I tested. I also created Xara3D banners for the "AAC" "standard" that got leaked and was only available as a proprietary Windows encoder and could only be played back in real time using K-Jofol.

Re: AAC/MP4/M4a Spectrum Analysis

Reply #8
Would it be fair to characterize that as an erroneous attempt to judge quality?
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Re: AAC/MP4/M4a Spectrum Analysis

Reply #9
Is Kode54 a friend of yours?. You both seem to like picking on people for no reason. I asked a simple straight forward question. Don't need the wet blanket brigade.

Re: AAC/MP4/M4a Spectrum Analysis

Reply #10
From my perspective he was empathizing with you.  We're both trying to help you, even if you don't see the reason, unless you actually have a good reason to be doing what you're doing.  Nevertheless, I already enabled you with the type of "help" you were seeking.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

 
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