Re: [PD] precision of vline~ and/or pd messaging

Hmm, I have to correct your message to get a more interesting answer from
you :)

the SR is 48K, and I'm using vline~ already. Theoretically with E Lyon's
objects I should also get more messaging precision, or maybe not at all?

João

I'm not sure if this is correct, so someone with a deeper knowledge of
Pd can confirm/deny... :)

125ms at a samplerate of (I'm guessing) 44100 would mean you're sending
a message to [line~]

every 5512.5 samples. Pd's default blocksize is 64, and when you
convert from a control value to

a signal value using the [line~] method then you are forced to start/end
the ramp on block boundaries. Since 64 does not divide into 5512.5 evenly then there is no way you can
perfectly recreate the

sine tone using this method. (I haven't looked at your example but I
would imagine that [line~]

forces the "remainder" to occur over the course of an entire blockthus
stretching out that part of

your sine wave to be longer than you want.)

You could recreate it using [vline~] however, because it will let you
start/end a ramp in the middle of

a block, thus giving you higher precision (presumably at a higher CPU
cost).

-Jonathan

...

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From: João Pais jmmmpais@googlemail.com To: PD-List pd-list@iem.at Sent: Tuesday, January 24, 2012 4:50 PM Subject: [PD] precision of vline~ and/or pd messaging

Hi,

please look at the attached audio file. It's a recording of a sinus
tone stored in an array, played back with consecutive segments of
125ms. If you look at each multiple of 125ms, you'll see there's a
glitch in the waveform. That means, the pd patch isn't fully precise
aliging the several fragments together. Or maybe the messaging isn't
precisely aligned with the audio. For this patch I'm using E Lyon's samm~ and click2bang~ to send the
messages, theoretically to have greater precision - and then some
counters and table readers make several calculations to get the indexes
of the segments. After these message-level calculations, the data goes
to vline~ reading from a tabread4~. My question is then: is it possible to get messaging and audio in Pd
ligned up, so that the resulting audio file is as precise as an
original osc~? If so, which objects or parameters should be used
instead?

Thanks,

Joao

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