Speed slider effect

I am a new forumite here. First of all I’m blind, and I use Windows 7 with JAWS screen reader. One of the things that really puts me off is the fact that you can’t use timetracks with Jaws! ARGH!! Because of the mouse. So, I was thinking of an effect that could be useful for those who are blind. I do not know how to program Nyquist, but I know what the parameters would be. It would be a pitch sliding effect that would slide the speed throughout the track from one percentage to another. Three parameters: “Start speed (percent)”, “End speed (percent)”, and “Interpolation” - options would be “Smooth”, an option to change the speed slower as the track progresses (more like a machine turning on if you go higher in pitch), or to change the speed faster as the track progreses (like something turning off if the indicated endspeed would be slower than the startspeed). Of course, this can apply to selection as well. Both positive and negative values could be supported just like in Change Speed or pitch or tempo, but this effect will do it like a tape player, i.e. sliding the speed. I have used Sliding Time Scale Pitch Shift but I would prefer a simpler effect to just change speed and tempo at the same time - it’s similar to what the effect “Tremolo/Vibrato” does when you select Vibrato, it would modulate the audio in the same way. For a blind person, they would have no choice but to just not do this without this effect. I have some old recordings of bagpipes, especially in 1917 where the record starts at one pitch and drifts higher - this effect would be an easy way to counteract the pitch change or drift, as the pitch changes with the tempo at a directly proportional level. I’m not sure where to post this thread but I am interested to know your thoughts. It would just be a new Nyquist plugin that would work for Audacity 2.0.6 and above. Thank you,


PS. I mentioned old bagpipe recordings - you know, I play bagpipes myself. Not sure we have any bagpipers on here that use Audacity extensively - let alone a blind one.

There is a Nyquist plugin called “turntable warp” which will gradually slow-down (or speed-up), like a record turntable, or tape slowing down or speeding-up, so it affects pitch and tempo . You can get a copy here … http://wiki.audacityteam.org/wiki/Nyquist_Effect_Plug-ins#Turntable_Warping_MS

Trying to manually correct a recording where the speed is not constant is difficult using Audacity’s “Time Track” feature.
Trying to perform that correction with “turntable warp” will be even more difficult , if not impossible.

There is (expensive) software which will automatically correct warped records & tapes, e.g. capstan … https://youtu.be/qqK6wgsh3QA?t=1m46s , ( a bit like autotune : automatic corrections are applied ~100 times a second ).
Apart from being expensive, ~$4000 , Capstan has a visual interface.

What you are describing does not sound as if it is very much “simpler”. The difference seems to be just that the tempo controls are coupled to the pitch controls. All you need to do to get the tempo and pitch to change together is to type the same values in the “pitch %” boxes and you type into the “tempo %” boxes.

In one way the effect that you are requesting is more complicated than the “Sliding Time Scale / Pitch Shift” effect, and that is that you want to be able to apply different types of interpolation between the start and end settings. An early experimental version of “Sliding Time Scale / Pitch Shift” had options for that, but they were removed for the release version because they were seen to be too complicated for many users.

If you want to request that interpolation options are added to the “Sliding Time Scale / Pitch Shift” effect, then we can count your vote for that.

If you want to request an option to couple the tempo and pitch controls in the “Sliding Time Scale / Pitch Shift”, then we can count your vote for that.

As Trebor wrote, there is the “Turntable Warping” effect that may be useful to you, but it does not work very well on long tracks, and it is not very precise.
It is very difficult to make a Nyquist effect that will accurately and precisely perform a sliding speed change on a long track.

If you want to request that Time Tracks are made accessible, the we can count your vote for that. It is arguably a “bug” that Time Tracks are not accessible, as Audacity aims to make all features accessible. Personally I think that this is the best option as it would have a major spin-off benefit of also making “envelopes” accessible.

Thanks for the replies. I have actually done a tempo/pitch change with the same values in Sliding Timescale, but there is a sort of bubbly-sounding quality that I can hear when doing it, as well as some frequencies being inverted (i.e. if originally in the center of the audio it gets switched over to the back/side channel of audio which sounds like it’s to the left and right of you and a hole in the center)… Not sure you are understanding what I’m trying to say. When I mean the tempo is coupled to the pitch, ok, um, it’s as if the speed were sliding from one percentage to another. My guess is that time tracks would modify the audio the same way as the effect I would like, but since time tracks are not accessible, then I prefer maybe to couple the pitch with the tempo as a checkbox in the Timescale dialog. If this box is selected, the tempo and pitch would change so that as if you were either speeding up a tape recorder or slowing it down. Maybe “analog” might be a better term, I don’t know. Also when I tried that experiment of changing the pitch and tempo at the same time, the pitch change did not seem proportional to the tempo change (i.e. the pitch and tempo are not always in synch with each other).
BTW, I have tried out Capstan. It does correct warping but, sadly, it does NOT work with bagpipes. Here is why. The scale of the bagpipe is not equal temperament - the intervals always vary, and even the tuning was radically different back in the record days. If it tunes the notes of the bagpipe to equal temp, the drone note will change. The objective is for the drone to stay steady. If the drone warps with the other notes with the same amount of pitch change, it is dead giveaway that it’s the record’s problem. Essentially I think the objective for Capstan is to keep track of only the drone, because, being that the drone is the steadiest note on a bagpipe… But what’s worse, it’s completely mouse-based! Uh-oh!

PS. Has anybody looked at Goldwave? They have some pitch change options that slide the pitch exactly how I described, but the envelopes (the contour of the changes) are different. I think they might have free trial version.

Hi there,
I haven’t visited this thread in forever but unfortunately it looks like no progress regarding this plugin. However, now that I have downloaded the FadePlus.NY plugin, I think I have a better understanding of what exactly the plugin should do. So, instead of fadeing, it would modify the speed of the file. Just as the vibrato plugin speeds up or slows down a part of the file by almost sweeping, I believe using the PWLv function or whatever, I think it would be easy to write a plugin that changes the speed of the file from one percent to another. If you say “Time tracks are good enough”, well, think again! Blind people can’t f**ing do that, you dudelsacks! Like I said before I know what the plugin controls would be. If you look at FadePlus.NY, I would use that as a starting point. My guess is that it only takes a bit of modification to change the fade effect to sliding effect, but the percentage values would be different in that they would indicate the deviation, just as it is in the Change Speed command. The speed slides could be Linear, Smooth, Exponential, elliptical or custom slide, exactly as in the FadePlus command. Then there would be “Initial change” percent, same type of values as used for Change Speed (so if you type in 100 for this box, it will start an octave higher because 100 percent will increase it by an octave). Then “Final change”, and if Custom slide is selected, Initial speed change and Final speed change. Of course there would be the * sound SRate and other variables in the plugin. Unfortunately, I have no experience writing Nyquist plugins myself, so I was thinking that somebody could help me write one which uses the commands I stated above. Maybe when I said “effect” I probably should have been more clear when I posted back in the Summer, because when I asked to see if a Phase vibrato could be created, it did happen because I stated it was a plugin, not a built-in effect. Hopefully this will make sense, but if not please just let me know. Thanks


PS. I have some ideas for other plugins as well but I would prefer to keep them in their own separate threads. They include Crossfade, Crossfade delete, Crossfade paste, and if possible a Nyquist version of Truncate Silence so that it can be customized to be more flexible than the in-built version.

Unfortunately it is not that simple. Fading is simply a matter of changing the amplitude of the sound. That is, the sound is multiplied by a scale factor. Nyquist includes a DSP function to allow sounds to be scaled my either a fixed amount, or by a varying control signal. Changing the speed is a matter of changing the sample rate (resampling). Nyquist includes a DSP function that allows a sound to be resampled by a fixed amount, but does not provide a function for variable rate resampling. Writing a variable rate resampling function is difficult. Writing a high quality variable rate resampling function is very difficult.