DC offset when downloading aif file

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sgardner7
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Joined: Sun Oct 29, 2017 2:11 am
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DC offset when downloading aif file

Post by sgardner7 » Sun Oct 29, 2017 2:18 am

DC offset when downloading audio file (aiff) from iPhone app called SuperNote. Voice is distorted. No change after clicking on DC offset box under Normalization. Headroom still missing. How to I download the file without this problem?
(Audacity 2.1.2 zip download)

kozikowski
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Re: DC offset when downloading aif file

Post by kozikowski » Sun Oct 29, 2017 5:41 am

Overload Distortion and DC Offset are different. You can have DC Offset all day long and the sound will be perfect except for a tiny volume restriction, and noting that production editing a DC Offset track will be a nightmare.

Can you get a screen grab and post it here on the forum? I think we need to see what the blue waves look like before we go too much further.

http://forum.audacityteam.org/viewtopic ... 49&t=64936

Here's a DC Offset sample. All it means is the blue waves don't settle to the zero line when you stop performing. The illustration is of a bad edit.

Image

Oh, and it's worth installing Audacity 2.1.3.

http://www.audacityteam.org/download/windows/

Koz

DVDdoug
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Re: DC offset when downloading aif file

Post by DVDdoug » Sun Oct 29, 2017 4:10 pm

Voice is distorted.
Is it distorted when you listen on the phone?

Did you actually download the AIFF via USB or did you make an recording via an analog connection?
No change after clicking on DC offset box under Normalization.
A waveform can be asymmetrical/offset without having "true" DC offset. A high-pass filter (maybe 20Hz) will usually help to "balance out" the waveform but like DC offset removal, it won't change the sound. (And sometimes tools/methods used to fix DC offset can sometimes cause an offset or cause a "click" at the beginning of the file.)

sgardner7
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Re: DC offset when downloading aif file

Post by sgardner7 » Mon Nov 06, 2017 9:59 pm

Thank you for your comments! I downloaded the latest version of Audacity 2.2.0
I then emailed my voice file from SuperNote on my iPhone 6. I used Audacity 2.2.0 to import the aif file and then I made a small clip to upload to this forum.
It is unintelligible. There is no distortion when I listen to the clip downloaded to my computer using VLC player. I just can't edit it nor convert it using Audacity.
2016 07-02 Journal clip.aiff
AIF file downloaded from phone via email then into Audacity
(203.59 KiB) Downloaded 14 times

steve
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Re: DC offset when downloading aif file

Post by steve » Tue Nov 07, 2017 10:35 am

sgardner7 wrote: I just can't edit it nor convert it using Audacity
Neither can I. It is a weird format, and I've not found anything that will play it correctly.
I've also been unable to find any support channel for SuperNote software.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

DVDdoug
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Re: DC offset when downloading aif file

Post by DVDdoug » Tue Nov 07, 2017 3:09 pm

There is no distortion when I listen to the clip downloaded to my computer using VLC player.
OK, Play it in VLC while recording the output from your soundcard with Audacity.

VLC should be able to convert the file to another format, but I've never used VLC for that.

sgardner7
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Re: DC offset when downloading aif file

Post by sgardner7 » Wed Nov 08, 2017 12:16 am

I followed the instructions for recording by changing to WASAPI since that was all that would give me stereo mix. I started playing the downloaded soundfile in VLC media player and clicked on the Audacity record button, and .... it worked! It sounds a little tinny but that can be corrected. Thanks! It is tedious approach to the 135 sound files I have on the iPhone 6, but it will get the job done. I appreciate it!
Steve

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