Old 03-29-2010, 04:56 PM   #1
kristen
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Default can i "subtract" one waveform from another?

i was recording a conference call on track 1.
it was getting long so I stopped recording on track 1 and went to the next track to continue recording.
I forgot to mute the first track while the second track was recording so the second track is "mixed in" with the first track.
Is it possible to take a copy of the first track and "subtract" it from the second track ... leaving only the second track by itself?

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Old 03-29-2010, 04:57 PM   #2
Jason Brian Merrill
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what if you put the first track out of phase from the second? Or perhaps i am getting to complicated?
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Old 03-29-2010, 04:58 PM   #3
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yes. press the "phase" button on one track.
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Old 03-29-2010, 05:04 PM   #4
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Assuming you didn't move the tracks forward or backward after recording you can try to invert the phase of track 1.
That should cancel out with the rerecorded signal on the other track.
To invert the phase of track 1 activate the button that's left of track 1's mute button.
With the fader of track 1 you can adjust the amount of cancellation.

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Edit: I'm too slow for this forum ...
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Old 03-29-2010, 08:23 PM   #5
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it didn't work.

track 1 contains track 1
track 2 contains track 1 and track 2.

the first track is embedded into the secongd track.

if i press the invert phase button and play both tracks, i still hear both tracks. is there a way to change the phase or is it just "in phase" and "out of phase"

Does it matter if it stereo or not?
I noticed that it recorded both tracks in stereo. i should have mentioned that but didn't really notice as i was concerned with the sound.

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Old 03-29-2010, 08:24 PM   #6
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look for JS: phase adjust in the JS plugins section, maybe that would work.

i would be more than happy to take a stab at it, if you wish.
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Old 03-29-2010, 09:09 PM   #7
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Quote:
Originally Posted by Jason Brian Merrill View Post
...i would be more than happy to take a stab at it, if you wish.
Yes, me too.
Can you upload a short snippet of the same part of both tracks?
(without any FX and best lossless, not .mp3)
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Old 03-30-2010, 06:42 AM   #8
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Default Do you mean you have 2 takes?

I'm wondering if people are misunderstanding the situation you are in. If you've recorded over audio into a track that already has audio on it, have you now got two *takes*? Does it look like you've got two tracks of audio (one above the other) together on one track? (If you've got your track panel heights small, enlarge them to be sure).

If so, right click on the track item - there should be a menu item called 'takes' (or something like that - not at a PC with Reaper at the moment). In there there shuold be something like "explode takes to separate tracks".

You should then be able to treat both tracks independently.

(Edit: Just re-read your posts - and I don't think you are in this situation afterall. Sounds like the audio from track one was routed to track 2 while you were recording. But inverting the phase of one of the tracks should help...)
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Old 03-30-2010, 08:06 AM   #9
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Quote:
Originally Posted by kristen View Post
it didn't work.

if i press the invert phase button and play both tracks, i still hear both tracks. is there a way to change the phase or is it just "in phase" and "out of phase"
The phase button takes it 180 degrees out of phase. If the first track had no FX when you recorded the 2nd track then it should cancel itself out.

However, the 1st track has to be in total alignment with the way the 1st track was dubbed to the 2nd track so you might have to shift the 2nd track back ever so slightly (it wouldn't take much). You can experiment by zooming in real close (probably into the sample level) and adjusting the 2nd track slightly back and forth to try find the position where the 1st track disappears the most.

Also the volume relationship between the two tracks may need to be adjusted.

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Old 03-30-2010, 09:00 AM   #10
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What Tod said...

>
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Old 03-30-2010, 10:07 AM   #11
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Quote:
Originally Posted by Blechi View Post
Yes, me too.
Can you upload a short snippet of the same part of both tracks?
(without any FX and best lossless, not .mp3)
Its pretty long. about 25 minutes on each track.

Do you think if I took about 10 seconds of each track ... and send as a wave file ... would that be enough for you to experiment? how much do you need?

Would i send two separate wave files?

where do i upload the files?

thanks
kristen
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Old 03-30-2010, 12:06 PM   #12
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anyone know how and where to upload the wav files?

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Old 03-30-2010, 12:14 PM   #13
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try dropbox?



https://www.dropbox.com/referrals/NTMzMDUyMDQ5

use that link


and then let me know!
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Old 03-30-2010, 12:25 PM   #14
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Quote:
Originally Posted by planetnine View Post
What Tod said...

>
+2

When the 2nd track recorded the output from the first, it's probably a few samples later than the original.


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Old 03-30-2010, 01:13 PM   #15
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If these tracks were recorded by reaper then the sources should have been recorded as Broadcast Wave Format (BWF) files. This means that REAPER should be able to time align them to the sample for you. Then all you have to worry about is matching the levels until the unwanted bit nulls.

Remember to invert the phase on only one of the tracks.

TO time align both tracks, select them both and then right-click/Item processing/Move items to source preferred position.

With faders further apart than the null point, the result will become louder; closer to null, quieter; at null, cancelled.

>
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Old 03-30-2010, 05:49 PM   #16
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I'm actually interested in how you managed to record track one onto track two? or maybe you mean one actual track but in Free Item Positioning Mode? maybe you could upload just the project file with no audio so we can see the set up.

And it's worth getting into the habit of saying "reversed polarity" as phase is not the right term and has to be referenced to another waveform to make sense but that's being a bit anal! Lol
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Old 03-31-2010, 08:20 AM   #17
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I seem to recall that in sonar at least. there was some way where you could take two tracks and have them render to a third track, but omitting all information that wasn't present in both takes. so say you could do this with 2 stereo channels and you could remove the vocals sometimes this way.

not sure if this would really help in this situation though, but it can be a cool thing anyways. i'm a little lost as to what exactly is the situation here with the two tracks and subtracting.
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Old 03-31-2010, 07:55 PM   #18
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Quote:
Originally Posted by Jason Brian Merrill View Post
try dropbox?



https://www.dropbox.com/referrals/NTMzMDUyMDQ5

use that link


and then let me know!

Jason,

I got a dropbox account.
I saved each track ("Track 1" and "Track 1and2") as two separate wav files. Track 1 is ok and about is about 34 min. "Track 1nd2 is the messed up one and is a little shorter in length.

What i did was start recording the conversation on track 1 and then after about 34 minutes created a new track 2 and started recording at the beginning of track 2. I armed track 2 and started to record but forgot to mute track 1 so it was playing out the speakers. Since i had my microphone on for occational chat , the microphone was picking up the playback of track 1 (through the speakers)as well as the on line recording ("what you hear"). so track 2 contained both. At least thats what i believe happenned.

How can i put these two wave files into dropbox for you to mess with? i never used it before

superkristen
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Old 03-31-2010, 08:01 PM   #19
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Quote:
Originally Posted by kristen View Post
Jason,

I got a dropbox account.
I saved each track ("Track 1" and "Track 1and2") as two separate wav files. Track 1 is ok and about is about 34 min. "Track 1nd2 is the messed up one and is a little shorter in length.

What i did was start recording the conversation on track 1 and then after about 34 minutes created a new track 2 and started recording at the beginning of track 2. I armed track 2 and started to record but forgot to mute track 1 so it was playing out the speakers. Since i had my microphone on for occational chat , the microphone was picking up the playback of track 1 (through the speakers)as well as the on line recording ("what you hear"). so track 2 contained both. At least thats what i believe happenned.

How can i put these two wave files into dropbox for you to mess with? i never used it before

superkristen
First i would suggest saving a version of the project and moving everything into one folder. In this case i would do this:

File, save project as...







and then...

well you basically put the entire project into a zip file, drag it into the dropbox public folder, let it upload, and copy the link (right click and get public folder link) and paste it here.

Or you can make a folder under the dropbox, share it with whomever you want specifically (you should have my email address already for instance) and then it will auto-sync with whoever you wish's dropbox.
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Old 03-31-2010, 09:33 PM   #20
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Jason,

Ok. i zipped the file as you show in the example. i am still not sure how to use dropbox, Besides i don't want to put it there so anybody can get it.
Do you want me to send to your email directly?


thanks
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Old 03-31-2010, 09:38 PM   #21
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Quote:
Originally Posted by kristen View Post
Jason,

Ok. i zipped the file as you show in the example. i am still not sure how to use dropbox, Besides i don't want to put it there so anybody can get it.
Do you want me to send to your email directly?


thanks
superkristen
sure thing. Just drop it in a special folder, then go to your dropbox account online, and share that folder with jasonbrianmerrill[AT]gmail.com
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Old 04-01-2010, 04:39 AM   #22
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ok. i think i did it. let me know if you received it
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Old 04-01-2010, 07:30 PM   #23
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ok this is really interesting

its hard figuring it out because it seems that the second conversation isnt interrupted by the first until later on, so theres some sync up issues...

but i was thinking if i could send an out of phase version of the first track to the second, without sending to the master, I could put those voices out of phase with some adjustment of the wave

neat little experiment. If i get anywhere ill dropbox ya
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Old 04-01-2010, 10:15 PM   #24
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Yes, it is a little tricky.
On track 2 the microphone was turned on and off a few times ... but it was when the microphone was on that it was when it was recording track 1 from the speakers.

Still on the parts of the track 2 where it includes track 1, you should be able to hear "just the track 1 part" if you mute track 2.

appeciate you messing with it. its not an important conversation, but it did get to be something that could be an interesting experiment.

by the way thanks for telling me about dropbox. it is pretty useful. i used to use "yousendit" for big files a long time ago and this is much easier

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Old 04-08-2010, 08:33 AM   #25
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Hi Jason,

Did u have any luck with the waveforms?

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Old 04-08-2010, 08:36 AM   #26
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Ill see where i got when i get home It's sketchy at best at the moment. It's basically "better" I think, but certainly not good still.
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