Corrupted audio files

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fred48fm
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Joined: 28 Aug 2019 09:52

Corrupted audio files

Post by fred48fm » 13 Jun 2020 23:19

Hi,

We notice since the last update something strange.

Some audio files get corrupted.
Has PF is the only program accessing these files, it's most probably a linked issue.

Sample :
- Original : http://48fm.com/ext/temp/Original.wav
- Corrupted : http://48fm.com/ext/temp/Corrupted.wav

Any idea ?

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radio42
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Re: Corrupted audio files

Post by radio42 » 13 Jun 2020 23:37

Do you mind explaining what makes you believe that ProppFrexx corrupts the files?
Respectively what exactly should be corrupted?
Both files play just fine here?!

So how are you testing things and what should actually be corrupt?

I even tried to play the files with some other audio players.
But even the ‘corrupted’ files just plays perfectly fine!

fred48fm
Posts: 55
Joined: 28 Aug 2019 09:52

Re: Corrupted audio files

Post by fred48fm » 13 Jun 2020 23:51

By corrupted, i mean audio artifacts added in the file. Some glitches. In every file where this happen, it's the same type of artifact.
You can hear the most in the end of the file.

I make a link with PF as it's the only program that access these files and the only program that actually add content (tags, etc) in the files.

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radio42
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Re: Corrupted audio files

Post by radio42 » 13 Jun 2020 23:55

That more sounds like an issue with your sound card!
The only data which ProppFrexx might add to audio files are meta data TAGs, But TAG data (in case of WAV files it’s actually RIFF INFO) would NEVER have an impact on the audio quality.
ProppFrexx never changes or manipulated any audio data! So I guess you assumption is Not correct.
Respectively the cause of artifacts must be somewhere else.

Have you tried to play your files on a different PC with a different player?! If not, just try it out.

As said, the files play just fine here.

fred48fm
Posts: 55
Joined: 28 Aug 2019 09:52

Re: Corrupted audio files

Post by fred48fm » 14 Jun 2020 00:11

I'm very sorry to insist but if you listen to the file i named "corrupted" you clearly ear the sound errors.
In attachment, a spectrum comparison. red stuffs are the errors.
Sans titre-1.png
It's not a soundcard issue as I just compare the WAV file on our PF system and the same WAV file from our backup server.
I really checked any other issue, like file system etc and there was nothing.

I've now changed PF settings to block writing to files and reloading whole backup...

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radio42
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Re: Corrupted audio files

Post by radio42 » 14 Jun 2020 03:50

Still, ProppFrexx isn’t writing to any audio data!
So what you are saying is physically impossible.

Have you excluded the possibility, that the errors have been added to the file from bit-errors happening on your hard disk?!
Or an other application accessing the files?

I even took a deeper look into the files:
BOTH files do not contain any (RIFF) LIST - INFO chunk, but only a FMT, JUNK and DATA chunk!
Which means, ProppFrexx has never touched these files. If ProppFrexx would have written any TAG data to the file, a LIST - INFO chuck would be present, as this is the only chunk ProppFrexx is writing (if you save meta data to it).
For playing audio files, ProppFrexx is only opening the file sin read-only mode!
Thus I heavily doubt, that ProppFrexx has anything to do with the artifacts.

fred48fm
Posts: 55
Joined: 28 Aug 2019 09:52

Re: Corrupted audio files

Post by fred48fm » 14 Jun 2020 13:07

Thank you for your time.

Then i will keep an eye on this disk...

By the way, the file i gave you are extracts, just for the audio part.

The full versions are here. Including all the metadata, etc :
Original (backup version) : http://48fm.com/ext/temp/Original__Degi ... st_bon.mp3
Corrupted file : http://48fm.com/ext/temp/Corrupted__Deg ... st_bon.mp3

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radio42
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Re: Corrupted audio files

Post by radio42 » 14 Jun 2020 16:18

I also checked the newly provided MP3 files!
Please check yourself, but the Corrupted file is a re-encoded version of the Original file:

The Original mp3 is a contains 10260 audio frames and is of type CBR (constant bitrate)!
While the Corrupted mp3 file only contains 10183 audio frames and is of type VBR (variable bitrate)!
And the Corrupted mp3 file is indeed corrupt, as its frames are broken resp. some frames are missing - thus the slippery sound, as any encoder simply skips broken/invalid mp3 frames.

As already said: ProppFrexx wouldn't somehow magically and automatically convert a MP3 file or any other audio file!
Thus, there must be a program or tool running on your machine, which explicitly converts your audio files!

fred48fm
Posts: 55
Joined: 28 Aug 2019 09:52

Re: Corrupted audio files

Post by fred48fm » 15 Jun 2020 13:49

Thank you for your reply.
The file was not re-encoded, that's the problem ! That's the point that make me think of a program that may overwritten some audio data.

By the way the file is not VRB (clearly indicated in the image).
Original file size : 10 797 742
Corrupted size : 10 801 510
I just encoded a test version in VBR (320kbps, best quality) size is much lower -> 6 408 255

I runned a quick diag on the two file, the original is clean, no error. The corrupted has >180 errors.
diag.png

To be complete, for a short period of time we used the option "Save metadata to audio tag" instead of the pfmd files.
We quiclky stopped as this option was making a huge, lasting, disk usage when first loading large files (audio drops in sound output).

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radio42
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Re: Corrupted audio files

Post by radio42 » 15 Jun 2020 15:13

Well, I used MP3checker and that indicated VBR for the corrupted file.
Writing meta data TAGs to the audio files is used by hundreds of users, including myself on over 150.000 tracks! No one ever reported such an issue - as such I am pretty sure and very convinced, that this is not related to ProppFrexx at all!

I also never experienced, that writing TAG data causes such a heavy IO load, as it is only used to write TAGs when you modify them, but what you explain is TAG reading!- which of course has to initially take place to initially read the meta data of all your library tracks - but this happens independently of the "Save metadata to audio tag" option. So this can also not be related
I guess we should be careful here to not mix up things and create confusion.
And even heavily reading TAG data from your files shouldn't be a issue for a modern and fast IO subsystem.
When you already experience audio drops at this point, you might read this post:
https://www.proppfrexx.radio42.com/foru ... ?f=5&t=915

However, back to your problem: It seems to be a fact, that something has modified many MP3 frames of that file - looks almost randomly.
ProppFrexx only touches the ID3 chunk and nothing else - but the errors of mp3 frames are changes all over the file.
Thus, the reasoning must be something different!

How did you create resp. provide the mp3 files for ProppFrexx the first place?
Seems, that you are having a backup - so did you simply copy them over?
Or did you encode them explicitly to mp3 at that time?
Have you checked your hard disk for defects?
And where are they stored, on a local hard disk, a network drive etc.?

In the end I am afraid I can only give some guidance here, but not finally solve the issue, as it doesn't seem ProppFrexx related.

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