gavspav

I'm having a play at making an av sampler/looper and I've found a few patches around the place and put them together.

It works pretty much but its a bit buggy.

I've got a phasor~ which is driving the audio buffer and I am taking snapshots of this (25 hz) and doing a bit of division to get the outputmatrix/index count.

Problem is it sometimes skips an index (see Max window in patch below).

Or maybe this isnt the problem - maybe the problem is that there is not always a grabbed frame available when its time to write the matric.

Whichever I seem to get a few dropped frames.

Edit---on closer inspection (by slowing down the phasor on playback) it looks as if jit.matrixset is writing to an index which is never specified by the index message variable. How is this possible? Hmm

Can anyone show me the error of my inexperienced ways?

filling-jit-matrixset-from-signal-datasnapshot

Video was getting to the matrixset before I set the index and so the last known index value was coming into play.

Comment or optimisation tips always welcome though!

Finding my way in the dark here but just in case anyone ever happens on this thread:

I think that setting interpolation to true for the jit.matrixset stops the flickering which I think is due to the snapshot~ occasionally missing/duplicating an index.

EDIT Nope. Completely wrong about that. Back to the drawing board.

Hi, can u please tell what was exactly the problem in your patcher because i have the same problem..??

Hi, can u please tell what was exactly the problem in your patcher because i have the same problem..??
thanks


Well actually I had 2 problems - 1 resolved one not:

The first one that when recording from webcam into a jit.matrixset buffer I would end up with oddframes at the wrong index.

This turned out to be because the frame was arriving at jit.matrixset before I had updated the index.

The second problem is that I seem to end up with blank (dropped?) frames withing the matrixset. I am driving the index from a phasor~ and snapshot~. I've tried messing with the frame rate, using metro and qmetro, altering the snapshot frequecy but cant seem to sort it out.

I am using the internal isight though - perhaps that is the problem?

The first one that when recording from webcam into a jit.matrixset buffer I would end up with oddframes at the wrong index.
This turned out to be because the frame was arriving at jit.matrixset before I had updated the index.

The second problem is that I seem to end up with blank (dropped?) frames withing the matrixset. I am driving the index from a phasor~ and snapshot~. I've tried messing with the frame rate, using metro and qmetro, altering the snapshot frequecy but cant seem to sort it out. 

I am using the internal isight though - perhaps that is the problem?


In this simple patch is possible for you to tell me why i cant see anything? i need the jit.matrixset because i want to add a delay..

Vasilis wrote on Wed, 04 November 2009 08:54

you need to tell jit.matrixset an index to which to write the incoming matrix. then you need to retrieve the matrix with the outputmatrix message. have a look at the helpfile. it's all right there.

Vasilis wrote on Wed, 04 November 2009 08:54In this simple patch is possible for you to tell me why i cant see anything? i need the jit.matrixset because i want to add a delay..

you need to tell jit.matrixset an index to which to write the incoming matrix. then you need to retrieve the matrix with the outputmatrix message. have a look at the helpfile. it's all right there.


How about me! I've searched the forums, read the manual and everything!

Is there any way of ensuring that all the indices get filled from the grabber?

No matter what I do I keep getting dropped frames which means gaps in the matrix and flickering on playback.

Except that it's not! The outputmatrix parameter is not documented in the reference, though it is in the help patch.

MIB wrote on Wed, 04 November 2009 11:51you need to tell jit.matrixset an index to which to write the incoming matrix. then you need to retrieve the matrix with the outputmatrix message. have a look at the helpfile. it's all right there.

Except that it's not! The outputmatrix parameter is not documented in the reference, though it is in the help patch.


gavspav wrote on Wed, 04 November 2009 15:11

didn't really study your patch thoroughly, but you're probably having issues because you are driving your snapshot~ and your qt.grab from different timers.

just set @unique 1 on your qt.grab, and use [t l b] to synchronously send the matrix and bang the snapshot~

gavspav wrote on Wed, 04 November 2009 15:11How about me! I've searched the forums, read the manual and everything!

didn't really study your patch thoroughly, but you're probably having issues because you are driving your snapshot~ and your qt.grab from different timers.  

Thanks for your response - I think you're right about the separate timers. Just using the tbl has helped alot.

I am trying to fill the matrix at regular intervals in time, as opposed to when the webcam grabs frames so perhaps I need to store the last grabbed frame and send that to the matrix every time my snapshot is triggered.

i would say just bang your snapshot~, qt.grab, and fill the matrixset all from the same metro at whatever timing you wish.

Filling jit.matrixset from signal data/snapshot~