Add speed multiplier to Change Tempo/Pitch

It’s good that a multiplier was added to Change Speed because using percentages is confusing. For example, To speed up audio by 2x, you would supply a percentage of 100%, and for 10x, you would supply 900%. In fact, -66.7% corresponds to 0.333x. So the multiplier is much more intuitive to use.

Also, the multiplier should be able to supply more than 3 decimal places. For an hour long track, it’s the difference between using 1/3x and getting the desired 20 minute output, vs using 0.333x and getting a 19 minute 58.8 second track.

Thanks. I added that feature :smiley:

Why does that matter? If you are trying to correct for a recording where the recording speed was slightly wrong, then you should be using “Change Speed” rather than “Change Tempo”.

My point is that the presumably artificial limitation to 3 decimal places is unnecessary. My use case for Change Tempo is to speed up parts of some video I’ve recorded without having the chipmunk effect of increased pitch.

Anyway if it wasn’t clear, my request is to have the multiplier for Change Tempo and Change Pitch. I saw that it was a successful feature request for Change Speed so I’m guessing it shouldn’t be too hard to implement. I would contribute if I knew how wxWidgets worked :stuck_out_tongue:

I’ve logged your request on the Feature Request page of the wiki.

Thanks to jxu for bringing up this topic. I agree with him 100% and have struggled with various work arounds for years. I too tried the wxWidgets route with no success. In 2016, Steve responded to one of my questions regarding the “Change Tempo” effect much in the same way as below. At the time, I couldn’t come up with a well thought up answer to his question as to why more precision is necessary. However I think we all agree that we appreciate Steve’s quick response to our posts.

Steve wrote
Why does that matter? If you are trying to correct for a recording where the recording speed was slightly wrong, then you should be using “Change Speed” rather than “Change Tempo”."

In my project, I am adding multiple similar, but not the same, recordings from different sources. I then fine tune them so that each is close enough to the same pitch and tempo. I can then copy sections of a recording that have Zero Crossings at the appropriate to enable precise “Cut Lines” without clicks or pops. Many of the changes are small with pitch difference less than a semi-tone, and length off by less than 50 or so milliseconds, but most are big enough to be noticeable. I always use “Change Speed” when possible. The problem Is that one recording might have a lower pitch, but a shorter duration. If I use the “Change Speed” effect to increase the length, the the pitch goes even lower. In this case I have to use “Change Pitch” to add a few Cents to the recording, then use “Change Tempo” to increase the length to the desired amount.

Steve’s recent adjustment to the “Change Speed” effect has really helped on recordings where the pitch and tempo aren’t caddywhompus like my example above. With three decimal points in the “Selection Length” section I can adjust the recording down to the exact millisecond. However, under the example in the previous paragraph, when I must use the “Change Tempo” effect, I can only adjust the length down to two decimal places making transitions between recordings noticeable and up to 10 milliseconds off. Yes, I can move the “Percent Change” up or down by a few 1000ths of a precent, but it is still trial and error and not as precise as adjusting the “Selection Length” like in the “Change Speed” effect.

Steve, hopefully I have been articulate enough in my response to finally answer your question: “Why does that matter?” Regardless, we really appreciate your hard work and the many improvements you have made over the years. I got a MacBook for Christmas and downloaded the Logic Pro X trial. I found that Audacity is usually is far easier to operate and is just as good or better than LPX for what I am doing. Thanks.

Experienced Audacity 2.x.x user on Windows 10
Newbie Audacity 3.0.x user on macOS Big Sur 11.x

Please upgrade to 3.0.2 - we fixed a couple of tricky issues that were in 3.0.0


Change Speed.png
Change Tempo.png
I updated to 3.0.2 just to be safe. I have included two different screenshots to compare the “Change Speed” versus the “Change Tempo” effect to demonstrate the variance in end result.

Using the example shown above, If I want to shorten the duration of the clip from 48.051 seconds to 48.000 seconds:

The “Change Speed” effect calculates the Percent Change as +0.106%. With 3 full decimal places under Selection Length, the resulting duration is 47.999980 seconds. This allows me to append the clip onto itself over and over again with perfect Zero Crossings at the beginning and end of the clip.

The “Change Tempo” effect calculates the Percent Change as +0.109%. Because the Length (seconds) only allows 2 decimal places, the resulting duration is 47.998 seconds, a full 2 milliseconds shy of the 48.000 second goal. If I adjust the “Change Tempo” Percent Change to +0.106%, just like the “Change Speed” effect, the resulting duration is 48.001, 1 full millisecond over 48.000 seconds in length.

I understand this seems like a small difference, but the project I am working on has multiple segments on one AUP3 file that I have to separate out and manipulate individually. Each clip uses unique instruments at different volumes. It only takes a couple of milliseconds of overlap to create an ear piercing click or pop. Over time the variance compounds and “Cut Lines” get sloppy.

I have enclosed a screenshot of both the “Change Speed” and “Change Tempo” effect on the same clip to highlight the differences. This example has a small variance in the outcome, but some clips I work with are much more extreme. In addition, sometimes I have to adjust the Tempo at an eighth note or smaller. The 3 decimal places used by the Selection Length in the “Change Speed” effect really help because I am using Start and End points at X.125, X.375, X.625, or X.875 seconds.

Thanks for your consideration. It is my hope I have made an adequate case for this programming change. Regardless, I really appreciate the time and effort that the Audacity team have put into the upgrade to 3.0.x. I don’t know how many times I have lost work because I moved or renamed the old AUP file, but not the _data folder that goes with it.

Experienced Audacity 2.x.x user on Windows 10
Newbie Audacity 3.0.2 user on macOS Big Sur 11.2

I also wish the artificial limitation of 20x change tempo were removed. I use the change tempo feature when editing my videos to speed up clips while mostly preserving pitch, and I have to use two applications of change tempo to get it to work. Thanks for your understanding.