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

[Jonathan Wilkes]

Ah, and I see in addition to your message you wrote vline~ in the title! Oops.

I don't know what click2bang~ does-- is it aligning its bangs to block boundaries?  That's just a guess.


-Jonathan




>________________________________
> From: João Pais <jmmmpais at googlemail.com>
>To: PD-List <pd-list at iem.at>; Jonathan Wilkes <jancsika at yahoo.com> 
>Sent: Tuesday, January 24, 2012 6:53 PM
>Subject: 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
>> 
>> 
>> 
>> 
>>> ________________________________
>>> From: João Pais <jmmmpais at googlemail.com>
>>> To: PD-List <pd-list at 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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>
>
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