From: Joćo Pais <jmmmpais@googlemail.com>
To:
PD-List <pd-list@iem.at>; Jonathan Wilkes <jancsika@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?
Joćo
> 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: Joćo 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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