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Author Topic: 'change speed' in Audacity 2.1.1  (Read 3367 times)

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Offline danny3

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'change speed' in Audacity 2.1.1
« on: September 15, 2015, 08:39:32 PM »
I have been using Audacity ver.2.0 for a while now. Last week I upgraded to the current version, 2.1.1.
I did this initially because I fowanted to experiment with adding some reverb to a dry vocal sbd track to mix with stage mics source. (I had researched a bit and knew that the vberb effect on the earlier version wasn’t so great.
I surely like the improvements in the update, but am lost on how to best perform the ‘change speed’ effect that I have up to now utilized when synching tracks from different recorders.

I have been paying attention to discussions here regarding changing speed, and its correlation to pitch, but so far in my somewhat limited experience have not felt the need to get deeper when mixing a @ 1 – 1:15 hour set.
I line up at the beginning, add and join whatever space is needed (copy/paste/generate silence) to the beginning of the track that is shifted over to the right so they start the same.
Then I find a common point as close to the end as is feasible, note the samples from each track, divide the larger by the smaller, remove the ‘1’ and two decimal places, and enter that number in the (version2.0) ‘change speed’ percentage box.  (I hope I explained that properly – it has worked well for me.)

Sometimes that percentage would be 13 decimal places long. With the newer version, I can’t seem to enter a percentage change past the thousands place (.00x)
I am hoping someone has some experience with this version, and can offer suggestions. I see that there is the opportunity to ‘change length', but can’t figure that out.

Thanks for any insight. Dan
« Last Edit: September 16, 2015, 11:21:41 PM by danny3 »

Offline danny3

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Re: 'change speed' in Audacity 2.1.1
« Reply #1 on: September 16, 2015, 06:29:38 AM »
For an example, in a current project the common point near the end is off by 4575 samples. The math gives me a percentage of .0019726379465. (This particular set was @ 1 hour, 25 minutes long)
In the Change Speed dialog box I can enter a new length, but where do I measure that from?

Edit to add: figuring out the offset gave me an idea, which seems to have worked.
I trimmed off the audio that I didn't need at the end of the longer file. The reference point is now about  8 seconds from the end.
I then subtracted the 4575 samples from the current length and entered that # of samples as the 'New Length' in the Change Speed dialog box.

(I used the term 'track' in my OP, maybe should have referred to it as 'file.')
In this project I was synching two files (sbd and stage lip pair) from a DR-680 with an audience stereo mic pull into a DR-2d. It wasn't feasible to run all into the same deck.

Still wondering if there is a more appropriate method. Thanks
« Last Edit: September 16, 2015, 11:22:31 PM by danny3 »

Offline Hypnocracy

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Re: 'change speed' in Audacity 2.1.1
« Reply #2 on: September 21, 2015, 09:54:25 AM »
I've done it many ways...the right way and the wrong way...but the quickest and dirtiest method I've come across for lining up two unique sources of the same set...

wait for it...


Using "Set Rate" for the individual track I find that I change the short one from 48000 to 47999 and 80% of the time I'm dead on...may be just the two units I use Stage FR2LE and Audience/SNB from Tascam DR680....IDK but on occasion I thought I heard some phase shift on play back of the two sources in the editor but never on mix down

Click on Track name for drop down menu at the bottom is "Set Rate" go to "Other" enter your sample rate. Very quick and visual to see the change.

I know this is too easy and I'll get shot down...but hey it's only rock-n-roll and I like it
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Offline morst

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Re: 'change speed' in Audacity 2.1.1
« Reply #3 on: October 09, 2015, 01:54:25 PM »
Genius! If Set Rate works, then it works! Done deal!

I would guess that each two recorders will have their own compensation numbers, but that's a great way to go about it, if you are getting the results you need.

..Using "Set Rate" for the individual track I find that I change the short one from 48000 to 47999 and 80% of the time I'm dead on...may be just the two units I use Stage FR2LE and Audience/SNB from Tascam DR680....IDK but on occasion I thought I heard some phase shift on play back of the two sources in the editor but never on mix down

Click on Track name for drop down menu at the bottom is "Set Rate" go to "Other" enter your sample rate. Very quick and visual to see the change.

I know this is too easy and I'll get shot down...but hey it's only rock-n-roll and I like it


Edit: here is my link to my method of synching files using the OLD version of audacity... http://morst.blogspot.com/2010/03/this-is-follow-up-of-sorts-to-my-post.html
« Last Edit: October 09, 2015, 01:56:08 PM by morst »

Offline Life In Rewind

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Re: 'change speed' in Audacity 2.1.1
« Reply #4 on: October 09, 2015, 02:05:57 PM »
Genius! If Set Rate works, then it works! Done deal!

I would guess that each two recorders will have their own compensation numbers, but that's a great way to go about it, if you are getting the results you need.

..Using "Set Rate" for the individual track I find that I change the short one from 48000 to 47999 and 80% of the time I'm dead on...may be just the two units I use Stage FR2LE and Audience/SNB from Tascam DR680....IDK but on occasion I thought I heard some phase shift on play back of the two sources in the editor but never on mix down

Click on Track name for drop down menu at the bottom is "Set Rate" go to "Other" enter your sample rate. Very quick and visual to see the change.

I know this is too easy and I'll get shot down...but hey it's only rock-n-roll and I like it


Edit: here is my link to my method of synching files using the OLD version of audacity... http://morst.blogspot.com/2010/03/this-is-follow-up-of-sorts-to-my-post.html

The whole sync issue is about juxtaposition of 2 clocks (the recorders) to the system clock (DAW)...thats what brings out the minor speed/pitch difference.

In this case it's minor - so the pitch and speed differences are only notable when making a matrix...we hear it as "drift"

Im sure at some time - many of us have played a 44.1k file back at 48k (due to bad header or something) - and had it play noticeably too fast/way out of pitch.

In that case - its obvious what's wrong....we need to tell the DAW to play that file at 44.1k - same thing is happening here...just with more minor differences in sample rate.

Offline danny3

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Re: 'change speed' in Audacity 2.1.1
« Reply #5 on: October 09, 2015, 06:43:30 PM »
After a bunch of successful matrices since I first posted about this, I wanted to reiterate that the method I tried to explain in my second post above using the ‘new length’ in the dialog box for the Change Speed effect has worked like a charm, and proven to be much easier than the calculations method I previously used (thanks morst!).

Offline capnhook

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Re: 'change speed' in Audacity 2.1.1
« Reply #6 on: October 10, 2015, 09:59:19 AM »
I still do the calculations, but now I can check my math with the answer in the "new length" box.

Big help, nice improvement.
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Offline morst

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Re: 'change speed' in Audacity 2.1.1
« Reply #7 on: May 26, 2016, 08:29:34 PM »
Yep.

They broke my favorite feature after 2.1.0.

2.1.1 and 2.1.2 both only allow three-digit precision in the overall percent field of Speed Change. NO GOOD!

They even let you type in the exact number of samples you wish the target to be, but under testing, they are not able to deliver bit-accurate results, as they seem to be rounding to the nearest .001%!!!!!  :facepalm:

I have downgraded to 2.1.0 for now. I hope that this is only a temporary fix.
https://sourceforge.net/projects/audacity/files/audacity/2.1.0/

Offline morst

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Re: 'change speed' in Audacity 2.4.2
« Reply #8 on: July 02, 2021, 07:13:34 PM »
they even let you type in the exact number of samples you wish the target to be, but under testing, they are not able to deliver bit-accurate results, as they seem to be rounding to the nearest .001%!!!!!  :facepalm:

I have downgraded to 2.1.0 for now. I hope that this is only a temporary fix.
https://sourceforge.net/projects/audacity/files/audacity/2.1.0/
Yes i would like to use this old topic, thanks for asking.
I just tested the "TYPE IN THE NUMBERS" interface on the now-current Audacity 2.4.2 (mac os) and the output precision is now correct!
I am able to adjust audio tracks to an exact desired length now, in order to accurately perform my "squash or stretch" time conversions for synchronization.


Gonna have to make a new spreadsheet with the math now that we need to know the numbers.
The new version will still take inputs of original length between sync marks, in samples, and either the difference needed, or the new length in samples.
But then, once we get the ratio of those, we'll need to enter the total length of the clip, in order to multiply by the newly-found ratio to get the new length of the entire clip.


Easily done; I already used it once, but I'll make a new version of the spreadsheet I guess, and try to make it straightforward.


That spreadsheet again:
https://docs.google.com/spreadsheets/d/e/2PACX-1vSgTr0RrSyAcaoRogQ8KJTYV31Lfs8QxDoA-dsecl0uCLQnn0XDjAkNM51EjviSLZoUO6erl4rDRGSP/pubhtml

Offline morst

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Re: 'change speed' in Audacity 2.1.1
« Reply #9 on: July 02, 2021, 08:58:53 PM »
In further use, although the percent display is truncated, the value itself seems to be stored!
When I typed in the length of set two of my current project, the resulting "NEW LENGTH" is exactly what my spreadsheet says I should use.
« Last Edit: July 02, 2021, 09:00:27 PM by morst »

Offline morst

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Re: 'change speed' in Audacity 2.1.1
« Reply #10 on: July 02, 2021, 11:44:55 PM »
damnit, is this a Fool Me Twice Won't Be Fooled Again issue?
Grr.
Fach. stay tuned.

 

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