• ### Fft unpack

hi,
first of all, as its my first post on this forum, i think i should introduce myself : i am a french student in sound engineering and i have been introduced to pure data a few month ago.
I have good knowledge of audio theory and lot of practice to, but i am not that good at programming or mathematics, eventhoug i have notions...

so, here i go with my question.

i am trying to create a simple patch with two audio input between wich i want to manually crossfade to morph them. kind of a convolved crossfader in fact.
but my problem is : how can i unpack the data that comes out of the rfft~, as puredata seems to considere it is audio signal?
or am i missing something fundamental??

cheers,
pierre.

• Posts 6 | Views 4231
• Hello, welcome Pr

Unpack the signal by writing each block (of 64 freq bins) to an array using [tabsend~] You can read whatever the current value is with [tabread]

Use the Source.

• I have sent my [rfft~] outputs to tables (thank you obiwannabe), but i do not manage tu unpack the serie of data that comes out of it...
I joined my patch to this message, maybe someone will feel kind enough to throw it a quick glance and tell me where i am wrong?

• main problem is that you're sending a message of [1 ( to the [tabread] objects. this means that you are only reading the table at index 1 every time, when actually the table has 64 samples for each block.

there are a few other problems in your patch too, like, for example, when you add to numbers together using a [+ ] object, you should make sure that the number to the right inlet is sent before the number to the left inlet, using the [trigger] object.

[metro] has a speed limit of 1ms. it can't play at smaller intervals than that. your [metro 9.9967e-42] will actually only send a bang every 1ms.

also, i really understand why you need to 'unpack' the fft data in the first place. for the type of multiplication and addition you want to do, you can probably get by with keeping everything in the signal domain.

good luck. FFT is powerful, but not really that easy to get working properly. if you have a good look through the pd audio help, section i, there are a few good FFt examples that might get you further on the right track. i03-resynthesis is always a good place to start for many FFt projects.

• and, fyi, you can skirt around metro's 1ms limit by rebuilding a metro using [delay]. I've recreated metro as [vmetro] in the latest pd-e autobuilds under senderfruit ([senderfruit/vmetro] should do the trick)

cheers

• ok,
first of all, i d like to thank everyone for paying attention to this topic.

after reading your answers, thinking a bit, and working on my laptop, here is what i came up with as a joined file.
looks like i get closer, but it still doesn't do what i want, wich should be an audio morphing...

if someone feals kind enough to throw an eye at my patch, it could be great support.

http://www.pdpatchrepo.info/hurleur/New_Folder.rar

Posts 6 | Views 4231
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