[chuck-users] other ways to live-code with time

Wed May 6 19:46:03 EDT 2009

Hello,
Last week I sent out an email to the list about a synchronization  
protocol I was working on with Perry and Dan for PLOrk. I thought I'd  
share the current product and invite you all to check it out, try it  
out, and give me feedback if you'd like. All relevant materials can be  
found at:

http://www.princeton.edu/~mcerquei/networking/

The protocol that was rather successful in testing is the Time-Tagged  
OSC (TOSC) and the source code for all that code is in the  
appropriately named folder. Apologies for the lack of comments in the  
source code for the new classes I wrote. The sample client and server  
programs I wrote have some comments which pretty much covers the main  
differences from OSC to TOSC. In the final report pdf file, the TOSC  
section will outline what's going on in general so that's worth  
checking out. You can also check out a demo that compares a controlled  
recording/TOSC test/OSC test in the Demo.tar file (it plays in  
Audacity).

I'll be continuing to work on this project next year for my senior  
thesis. There are a number of things I already want to fix/work on,  
but recommendations/suggestions are, again, very welcomed!

1. Code everything into the ChucK source code. Everything is written  
in ChucK right now so it can be made more efficient by coding directly  
into the source.
2. Improve the NTP protocols. My algorithms to synchronize clocks/ 
calculate good time-to-open offsets are very, very, very crude and can  
certainly be improved on. Better NTP = better synchronization.
3. Netclock - Making TOSC interoperable with Netclock would be useful,  
as Kassen mentioned in an earlier email.

Thanks!

Best,
Mark

On Apr 29, 2009, at 1:30 PM, Kassen wrote:

> Mark,
>
> That seems quite similar in approach to this;
> http://netclock.slab.org/wiki/index.php/FAQ
>
> I'd like to invite you to have a look at that and perhaps join the
> mailinglist on it. If these two could be made inter-operable it could
> be used to sync ChucK to a range of other open source music and
> graphics systems.
>
> Yours,
> Kas.
>
> 2009/4/29 Mark Cerqueira <mcerquei at princeton.edu>:
>> I've spent this semester doing some independent work with Perry and  
>> Dan on
>> how to get good network synchronization for PLOrk so that we don't  
>> need a
>> conductor and can focus on doing other things. I implemented a Time- 
>> Tagged
>> OSC protocol similar to the stuff Adrian Freed does. Essentially the
>> protocol first synchronizes everyone's clock via a protocol that is  
>> based on
>> the Network Time Protocol (NTP). On the PLOrk network, one machine  
>> runs as a
>> NTP Server and all others run as NTP Clients - NTP Clients  
>> calculate the
>> offset of their VM time to the server VM time, as well as keeping  
>> track of
>> the round-trip time of packets sent to synchronize to account for  
>> that in
>> the offset.
>>
>> Once the clocks are synchronized, packets sent over the network  
>> include the
>> current time (which should be synchronized pretty closely if the  
>> above
>> protocol works) and a time-to-execute offset. When someone receives  
>> the
>> packet they add the current time plus the time-to-execute offset and
>> schedule the packet to be opened only at that time. The NTP-like
>> synchronization protocol I described above also keeps track of all  
>> RTTs and
>> broadcasts to everyone what a good time-to-execute field is (i.e.  
>> make sure
>> we give enough time for the packet to travel over the network). If  
>> all works
>> well, everyone should open the packet at the same time.
>>
>> Not sure how successful this implementation will be...I'm testing it
>> tomorrow during PLOrk rehearsal! If anyone's interested in seeing the
>> code/my write-up I can pass around a copy once I *crosses fingers*  
>> complete
>> it and hand it in on Monday.
>>
>> Best,
>> Mark
>>
>> Tom Lieber wrote:
>>>
>>> On Wed, Apr 29, 2009 at 12:28 PM, Kassen <signal.automatique at gmail.com 
>>> >
>>> wrote:
>>>
>>> Yeah, a wireless network. And for whatever reason (AirPort  
>>> updates, OS
>>> X updates, variation in laptop hardware), timing issues got worse  
>>> from
>>> the previous year. Actually, I don't know how this was solved in the
>>> end, because I think things had improved by the end (or maybe we
>>> stopped relying on the network so much and I didn't notice)...
>>>
>>> On Wed, Apr 29, 2009 at 12:27 PM, Daniel Trueman <dtrueman at princeton.edu 
>>> >
>>> wrote:
>>>
>>>>
>>>> On Apr 29, 2009, at 11:36 AM, Tom Lieber wrote:
>>>>
>>>>>
>>>>> A lot
>>>>> of rehearsal time in PLOrk this past semester was dedicated to
>>>>> synchronizing the performers because we lacked good network
>>>>> synchronization.
>>>>>
>>>>
>>>> i've come to view this as a feature, not a bug... ;--}
>>>>
>>>
>>> I chose my words carefully! There's no way I can view getting
>>> everybody to practice being in sync as a bad thing, but having the
>>> option of good network synchronization means we can make pieces  
>>> where
>>> players can give their full attention to something else, like making
>>> patterns in beepsh.
>>>
>>>
>>
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