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Computer Forensics World :: View topic - Audio File Authentication/Integrity Examinations
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Audio File Authentication/Integrity Examinations

 
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alcool179
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Joined: Feb 18, 2016
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PostPosted: Fri Feb 19, 2016 2:17 am    Post subject: Audio File Authentication/Integrity Examinations Reply with quote

Hi all,
i would check the authentication and the integrity of a audio (wav) file. Especially I would check if this file is been cutted, or if there has been tampering.
Can you suggest open source software for check the audio file integrity?
The spectrogram examination with Praat oor SOX can help me for this evenience?
Which technique can I use?
Thanks
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cybercop
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Location: Marion, Indiana, USA

PostPosted: Fri Feb 19, 2016 7:18 am    Post subject: Reply with quote

If you are asking this question, YOU are not the one to be digging in to it. There are companies that specialize in audio examination. Determining if an audio file has been edited can be a tedious task and involves looking at the waveforms in sections measured in milliseconds.

As for the technique, hire a professional.
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alcool179
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PostPosted: Fri Feb 19, 2016 9:16 pm    Post subject: Reply with quote

Hi cybercop, I know there are professionals, but I'm studying for myself.
I'm trying to learn techniques and software.
I asked if someone with more experience than me, could help me, and give me more input for better understand. Or maybe suggest me some lectures or link/guide or papers...

thanks
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alcool179
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PostPosted: Tue Mar 08, 2016 2:31 am    Post subject: Reply with quote

I seen that for evaluate an alterations in an audio recording is possible to analyze a change in the noise floor.
Someone can tell me how to visualize with praat or sox or with other open source software the changes of background noise.
Using the spectrogramm analysis, how can I show this changes of noise floor?
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SgtJackie
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PostPosted: Tue Mar 08, 2016 8:07 pm    Post subject: Reply with quote

Have you tried Audacity?
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alcool179
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PostPosted: Wed Mar 09, 2016 11:18 pm    Post subject: Reply with quote

How to do?
Can you indicate me a guide or the steps for visualize it?
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SgtJackie
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PostPosted: Fri Mar 11, 2016 7:22 pm    Post subject: Reply with quote

"http://audacity.en.softonic.com/download"

It is a free download and very easy to use. Just open the sound file and you will see the wave form. There are various tools to expand it and examine it in detail. Expand the waveform and you should be able to spot whether anything has been cropped or added in.

Moderator Note: Direct links are not allowed.
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SgtJackie
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PostPosted: Tue Mar 15, 2016 7:53 pm    Post subject: Reply with quote

Sorry mod Sad TY for fixing it.
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alcool179
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PostPosted: Tue Mar 15, 2016 10:49 pm    Post subject: Reply with quote

Thanks for your suggestion.
I'm using audacity for view waveform and spectrogram.
But how can be able to spot whether anything has been cropped or added in?
Confused
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cybercop
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PostPosted: Tue Mar 15, 2016 11:13 pm    Post subject: Reply with quote

Zoom it in until you are only seeing about 1 second across the entire waveform. Then look VERY closely at every section. You are looking for areas where the waveform makes a dramatic (most likely a straight vertical line) change in the pattern of the waveform. Any vertical straight lines can be suspect (Please note the "can be suspect" part. This does not guarantee it has been altered). When you are dubbing video, it is difficult to get it aligned properly and you are looking for signs of misalignment. If you break out a web browser and google you can find some suggestions as to what you should be looking for.
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