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Distorsion unless I use quicktime

jackoverfull

jackoverfull

macrumors regular
Original poster
Dec 3, 2008
179
81
Berlin, Germany
Hi people, I'm having a pretty strange audio issue.

I'm trying to salvage parts of a concert recording that was took using an iPhone while streaming it on Mixlr.

If I listen to the .aac file in QuickTime Player (X or 7) everything is fine, but if I export the file as an AIFF or import it into iMovie I get pretty strong distorsion, even if I play it in QuickTime (but in quicktime I can lower the amount of distortion if I lower the volume, altough never remove it completely.

Since the distorsion isn't there in the original form it would seem some sort of odd exporting problem, but I've been scraping my head for hours and haven't found a solution.

I'm linking the file, every suggestion is quite welcome.

www.sormorock.com/tmp/Todisco2016-1.aac
 
Can you play the file UNdistorted using QuickTime player?

If the answer is "yes", then try this:

You will need something like AudioHijack or AudioHijack Pro. These are apps that can "capture audio" while it's being played on the Mac.

Set up AudioHijack to create an "aiff" file.

Start the "capture" and NOW play back the audio in QuickTime player. When the file is done playing, "close" the capture. You should now have an aiff file created from the original. (this must be done "in real time")

Does the resulting aiff file play without distortion?
 
I opened your file in QuickTime Player and exported the audio. It sounded fine. GarageBand imported and it wasn't much worse. iMovie and iTunes opened it too.

I think part of the problem is that what you uploaded isn't an audio file. It's a movie file. There is also the possibility that the filename might be confusing some of your apps because you have two periods in it and it looks like there are two file extensions. Then again, it's a very low quality recording at 62kbps and it will never sound good.
 
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62kbits?
chabig is right. You're not going to "squeeze much quality" out of that one!
 
chabig said:
I opened your file in QuickTime Player and exported the audio. It sounded fine. GarageBand imported and it wasn't much worse. iMovie and iTunes opened it too.

I think part of the problem is that what you uploaded isn't an audio file. It's a movie file. There is also the possibility that the filename might be confusing some of your apps because you have two periods in it and it looks like there are two file extensions. Then again, it's a very low quality recording at 62kbps and it will never sound good.
Click to expand...

Could you mail the exported file to me/upload it somewhere?

Yes, quality is what it is, but it's mostly listenable in QuickTime player, without the odd distortions I'm hearing when I export it.
[doublepost=1547941130][/doublepost]
Fishrrman said:
Can you play the file UNdistorted using QuickTime player?

If the answer is "yes", then try this:

You will need something like AudioHijack or AudioHijack Pro. These are apps that can "capture audio" while it's being played on the Mac.

Set up AudioHijack to create an "aiff" file.

Start the "capture" and NOW play back the audio in QuickTime player. When the file is done playing, "close" the capture. You should now have an aiff file created from the original. (this must be done "in real time")

Does the resulting aiff file play without distortion?
Click to expand...
Yes, using SoundFlower to rerecord it is my last resort but I'd like to avoid that, as the resulting file would have even less quality.
 
OP:

I downloaded the linked file from post 1 above and then went to work on it.

I will offer two options for you.

OPTION 1:
Download the free app "QTAmateur" from here:
https://www.mikeash.com/software/qtamateur/

This is a small, old app, BUT IT STILL WORKS.

Next, open your file with it.
Now, go to the "file" menu and choose "export".
Down toward the bottom, select the output format you want (I suggest aiff).
Check the "settings", but they are all pre-set for aiff.
Give it a name and export it to wherever you wish (I suggest the dekstop).

Now, you can open BOTH files in QTAmateur "side-by-side" for comparison.
The exported file sounded as good as the original to me.
(remember, the original is a low bitrate file, so you're NEVER going to get "more quality" than the original, which is not the best).

OPTION 2:
Download the free app "All2MP3" from here:
http://www.tucows.com/preview/753945/All2MP3

Now, open All2MP3.
"Drag and drop" the icon for the music file into All2MP3's window.
All2MP3 will ask what quality you want (move the slider all the way to the right for best quality).
I suggest that you DO NOT check the box to trash the original file after converting.
Then, let All2MP3 convert the mp4 file to a high-quality mp3 file.

Again, use QTAmateur to open both files side-by-side for an audio comparison.
 
Thanks. Tried with both and no luck so far.

Also, I've realized this small snippet to better illustrate the issue: I've used SoundFlower to record the output from QuickTime Player while playing the same short section from the original, "good" sounding, file and the exported aif (done with QTAmateur, but every other program gave the same results so far), the difference to me is stricking. Do you get something different on your system?

www.sormorock.com/tmp/repent_fragment.aif


Also, notice how different the playback of the supposedly identical section looks:
5b8YzOQ.png



I guess that recording the output of the original file using SoundFlower could be my solution, still it would be good to understand the problem and to find a better workaround.
 
The waveforms look identical to me, as well.

I provided you with 2 good options in reply 10 above.

Either your ears are better than mine, or you're making mountains out of molehills and you will never be satisfied with the results.
 
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It's a stereo recording: the left and right sections should be identical, the bottom and upper ones are...Because that's the same recording.

Also, did you listen to the brief snippet? Is really not identical at all here, with clear distortion on the highs on the second snippet.
[doublepost=1548114275][/doublepost]Should have posted only one channel, I guess, sorry for not making that clear.
 
62kbps is bad enough. 62kbps in stereo is probably worse than AM radio, maybe barely above telephone quality, if even that.

If you are happy with the original and you recorded the output of the acceptable sound output from QuickTime player but don’t like the result, I can only speculate that there simply isn’t enough data to work with.
 
Again, did you hear the snippet? Even if the file was "worse than AM radio" (perhaps) I can't see why QuickTime would play it back with listenable quality but not be able to convert it.
 
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