lost sync warning

lost sync warning

[Mac]

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Hi,

I did some normalization of some mp3 files and on some got the warning:

sox WARN mp3-util: MAD lost sync


The resulting files seem to be ok, i.e. they seem to play from beginning to
end (I have the pre normalization version of the file for comparison)

Also, the resulting files are much smaller. Sometimes megabytes smaller.
Whats up with that?

And, does normalizing an mp3 multiple times degrade the audio?

Regards,
Mac

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Re: lost sync warning

[Jeremy Nicoll - ml sox users]

On 2018-06-21 19:54, Mac wrote:

> Also, the resulting files are much smaller. Sometimes megabytes 
> smaller.
> Whats up with that?

I don't know if sox preserves bit rates, compression types of the input 
files
when it creates output files; the manual suggests not - since it 
describes
'default' compression options being used and mentions sox's "-C" option 
for
choosing what you actually want.  (I've only ever created MP3s as the 
final
result of processing WAV files.)

I'd be inclined to run soxi against input and output files to see if 
rates
or compression type have changed.  Also use sox with the stat and/or 
stats
'effects' to find things out about the files.

Also see the 'soxformat' manual for specific notes on different audio 
file
formats.

-- 
Jeremy Nicoll - my opinions are my own

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Re: lost sync warning

[Måns Rullgård]

Mac <macdroid53@gmail.com> writes:

> Hi,
>
> I did some normalization of some mp3 files and on some got the warning:
>
> sox WARN mp3-util: MAD lost sync

That means the mp3 decoder didn't find a frame sync code where it
expected one.  This could be due to file corruption or simply a trailing
ID3 tag.

> The resulting files seem to be ok, i.e. they seem to play from beginning to
> end (I have the pre normalization version of the file for comparison)
>
> Also, the resulting files are much smaller. Sometimes megabytes smaller.
> Whats up with that?

The output probably uses a lower bit rate setting.

> And, does normalizing an mp3 multiple times degrade the audio?

Yes.

-- 
Måns Rullgård

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