Hello everyone,

Is there a way using tabplay~ to reverse the playback of an audio file?

Thanks

-H

No there isn't. However [tabread4~] can do it without a problem and is nearly as easy to use. You can use all audio emmitting objects to index a [tabread4~], where the most evident objects are a [line~] or a [phasor~]. Both these objects (can) go from 0 to 1 which is what you need to read the samples out of a table.

[frequency\
|
[phasor~]
|
| [tablelength] --> this is not an actual object of course
| |
[*~]
|
[tabread4~ myTable]
|
[dac~]

This player plays the sample forwards. It's not difficult to make it go backwards.

D.

@domien said:

[tabread4~] can do it without a problem and is nearly as easy to use. You can use all audio emitting objects to index a [tabread4~], where the most evident objects are a [line~] or a [phasor~]. Both these objects (can) go from 0 to 1 which is what you need to read the samples out of a table.

[frequency\
|
[phasor~]
|
| [tablelength] --> this is not an actual object of course
| |
[*~]
|
[tabread4~ myTable]
|
[dac~]

This player plays the sample forwards. It's not difficult to make it go backwards.

Hi, I'm wondering, how to use this for reverse / forward playback in such a way that the soundfiler reads what the size of the file is, and these numbers are fed to a phasor~ in such a way that -1 will play the whole duration of the sample backwards and 1 will play the whole duration of the sample forwards.

I've tried to calculate like this:

soundfiler
|
numberbox (672000, for instance)
|
/ 10000000
|
numberbox (0.0672)
|
hslider
|
numberbox
|
sig~
|
phasor~
|
*~ (this receives the original number, 672000, for instance)
|
tabread4~ (arrayname)

however, when i then load a 336000 length sample, this same calculation goes completely awry and does not work properly.

sorry, it's late and i'm not reading full posts...but i GUESS that tabread~ (not tabread4~) is ok for reverse play at original speed, and would save on quite a bit of cpu.

You need to compute a few values with the output from [soundfiler].

First it’s helpful to think of how Pd stores audio files in arrays. If your sample length is 672000, [soundfiler] will, provided you use the -resize flag, fill an array with values from 0 to 671999. If the sample length is 336000, from 0 to 335999, etc.

Since [phasor~] outputs values from 0 to 1, we only need to multiply its output by the output from [soundfiler] and pass this new value into [tabread4~] to play the audio from beginning to end.

However, the frequency of [phasor~] also needs to be adjusted so that a single cycle of [phasor~] is the same duration as your audio file. This is done by dividing 44100 (assuming that’s the samplerate of your audio file) by the output of [soundfiler].

Having computed the [phasor~] frequency, you can now scale it to change the sample’s playback speed, or multiply it by -1 to reverse sample playback.

The attached patch should do what you need. You can pass messages into its inlet to control it:

1: forward, normal speed
-1: reverse, normal speed
0.5: forward, half speed

… and so on.

http://www.pdpatchrepo.info/hurleur/msx2~.pd

On doing a search this is a great patch but doesn't work doing reverse audio as suggested. Should it work using -1 ( as does for doubling or halving sample rate)?

@donnerbono Yes it does work....... try this.......
reverse.zip
open [master_patch] and then click the [-1( message.......
David.

@whale-av Thank you. That works great!