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two sfplay~ loop 1 phasing??

January 22, 2013 | 5:52 pm

Hello,

I have a Cubase project which is in 2/4 at 100 bpm.
I export two click track loops: one is 1 measure long, i.e. 1200 ms, and the other is 8 measures long, i.e. 9600 ms.
I open these two stereo 44100Hz 16 bits wav files in two sfplay~ and sfinfo~.
sfinfo~ tells me the first one is 1200 ms long and the second is 9600 ms long.

When I send a signal 1 in both sfplay~, both loops begin playing together.
But after 5 minutes they get out of sync…
How is it possible? Am I becoming crazy?

I have a MacBook Pro 2.3 GHz Intel Core i7, 8 GB 1333 MHz DDR3 running Mac OSX 10.7.5 and Max 6.0.7
I have an I/O and signal vector size of 128, sampling rate is 44100Hz, scheduler is in overdrive, in Audio Interrupt off, and vector optimization on.

Thanks for your help, I really don’t understand this.


January 22, 2013 | 6:37 pm

I’m not sure whether sfplay~’s looping is sample accurate or not. You could test this by creating a 2 sample long file in audacity with two different values and seeing what happens when you loop it.

If you want sample accurate looping, I’d recommend the buffer~ based playback objects, as I know for sure that those can do it. (groove~, rate~ and wave~ should get you there)


January 22, 2013 | 6:45 pm

I have 25 loops to play at the same time, if I use buffer~ I wonder if it’s not gonna too much for my memory


January 22, 2013 | 6:59 pm

OK it’s good to know:
sfplay~ is not sample accurate and is not good to deal with loops and regular tempos.
better using buffer~
I wish somebody told me this months ago…


January 22, 2013 | 7:13 pm

10 megs for 1 minute of 16-bit stereo audio; chances are you’ll be just fine on RAM, unless your files are gigantic.


January 22, 2013 | 8:08 pm

Is there a way to monitor the RAM?
I know there is the DSP CPU Monitor, but is there an equivalent for the RAM?


January 23, 2013 | 12:50 am

i did this waaay back with the help of the shell external.
so get the shell external and try this:

– Pasted Max Patch, click to expand. –

hope it helps (tested with max 5.19 on mac osx 10.8.2)
hans


January 23, 2013 | 3:28 am

Thanks.
I’ve ended up with the buffer~ and groove~ solution. Much more accurate.
I have no idea what is the shell external but thanks anyways.


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