[chuck-users] syncing computers with OSC

mike clemow gelfmuse at gmail.com
Wed Jan 28 15:59:39 EST 2009


We looked into doing this while running Chucks on a cluster here at
NYU and realized that for things like sample-accuracy (or
sub-sample-accuracy, god forbid) even NASA has significant problems.
I think that some sort of hardware system (cesium clock or something)
is necessary for that.  Obviously, that's outside of everyone's
budget.  ;-)

But syncing tightly enough for musical performance should be totally possible.

-Mike

On Tue, Jan 27, 2009 at 10:22 PM, dan trueman <dtrueman at princeton.edu> wrote:
> well, we actually do a lot of synchronization over the network, and it works
> amazingly well (with UDP). it's nowhere near sample accurate, but it's
> musically powerfully accurate, and it's important to keep in mind that
> "accuracy" in something like plork is not easy to define, since all the
> sound sources (multichannel hemispheres) are spatially separate and there is
> a lot going on with phase -- the speed of sound becomes a major factor!
> if you are mixing multiple computers with a mixer, then i can well imagine
> that network sync will be insufficient, but when the room is doing the
> mixing, it is almost overly accurate; it feels un-natural how well a large
> ensemble can sync this way (and it is!).
> dt
>
> On Jan 27, 2009, at 7:39 PM, kevin wrote:
>
> nobody in plork or slork is synced, which is, in my opinion, one of its
> stronger points. the music sounds more attached to the performers and less
> attached to a computer, if that makes any sense.
>
> intra-computer sample-accurate syncing over a network is difficult because
> neither TCP nor UDP are suited to such things. TCP guarantees packet
> delivery by requiring a call-back (sometimes called a handshake). if the
> sender does not receive a call back, it assumes that the packet was dropped
> and then resends info. this works for things like websites, where the
> request is not time-sensitive.
>
> UDP on the other hand, does NOT guarantee packet delivery, and thus expects
> no call back. when packets get dropped over UDP, the sender is not notified,
> so the sender will not resend. this is better in situations like VoIP, where
> a single dropped packet will not ruin the audio stream (sure, there'll be a
> noticeable glitch). the idea is that if you're talking to someone, you'd
> rather hear a glitch than hear that packet arrive 5 seconds later.
>
> without modification, neither are sufficient for real-time synchronization.
>
> and even if they are, wifi bandwidth will definitely get in your way. i
> haven't looked at any numbers, but i'd intuitively guess that wifi drops
> more packets than wired.
>
>
>
> On Tue, Jan 27, 2009 at 4:15 PM, <james.hurlbut at utoronto.ca> wrote:
>>
>> I see. so none of the Plork pieces are dependant on precise
>> synchronization? I guess because I am coming from a dance music background
>> its more critical for me that the music is running off a master clock. I was
>> thinking that Chucks strongly timed quirkiness would enable me to send
>> sample accurate osc messages albeit at a very high speed cost. I suppose I
>> can try midi but was hoping for a wifi solution.
>>
>> Quoting dan trueman <dtrueman at princeton.edu>:
>>
>>> i don't think there is any way to get sample-accurate sync via
>>> conventional networking...
>>>
>>> dt
>>>
>>> On Jan 27, 2009, at 6:51 PM, james.hurlbut at utoronto.ca wrote:
>>>
>>>> Hi, chuck newbie here. I am wondering what the best way to get sample
>>>> accurate sync between two laptops. I have tried using
>>>> http://music.princeton.edu/~dan/plork/autosocket_chuck.zip but the two
>>>> computers receive the 16th beats at slightly off times. I also have
>>>> tried sending an osc message every sample or 100 samples but that
>>>> completely bogs down the machine. Is the solution to have one machine do
>>>> all the audio and another just send program changes? Thanks,
>>>>
>>>> James
>>>>
>>>>
>>>>
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>>
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