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

João Pais jmmmpais at googlemail.com
Wed Jan 25 09:56:11 CET 2012


> 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.

better to leave it to the author to describe it  
(http://www.somasa.qub.ac.uk/~elyon/LyonSoftware/Pd/):

samm~ sample accurate multiple metronomes, with click signal articulation
click2bang~ Convert click trigger to a bang

according to the author, putting these 2 objects in a row gives a very  
precise metro.


and here a link to a thread with iohannes and lyon:  
http://markmail.org/message/7usetdchjlqyk3eu#query:+page:1+mid:7usetdchjlqyk3eu+state:results

João

>
>
> -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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>>>>
>>
>>
>> --Friedenstr. 58
>> 10249 Berlin (Deutschland)
>> Tel +49 30 42020091 | Mob +49 162 6843570
>> Studio +49 30 69509190
>> jmmmpais at googlemail.com | skype: jmmmpjmmmp
>>
>>


-- 
Friedenstr. 58
10249 Berlin (Deutschland)
Tel +49 30 42020091 | Mob +49 162 6843570
Studio +49 30 69509190
jmmmpais at googlemail.com | skype: jmmmpjmmmp



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