[chuck-users] syncing computers with OSC

Tue Jan 27 21:51:13 EST 2009

i think the term "sample accurate" threw me off...

i was responding to it as "sample accurate for every single sample"

sample accurate every couple of measures or every couple of beats changes
things a lot (making it easier)

-kevin

On Tue, Jan 27, 2009 at 6:00 PM, Robert Poor <rdpoor at gmail.com> wrote:

> James:
>
> I'm a little confused.  You asked if you could get sample accurate ChucK
> sync between two laptops.  Yet it appears that everyone is trying to tell
> you how you can (or can't) pass synchronized performance data among laptops,
> how bandwidth and latency will get in the way, etc.  The two problems are
> very different.
>
> I'm assuming that you really just want to synch multiple ChucK VMs, not
> pass massive amounts of data.
>
> I am not a ChucK expert, but IF it is possible to slave a ChucK VM to the
> system clock on its local machine, then each ChucK VM will then be as
> closely sync'd as its respective host's system clock.    For sake of
> argument, let's assume this is true.  [Could a ChucK expert weigh in here
> and say if this is possible or not?]
>
> So the problem reduces to sync'ing system clocks on multiple laptops.  In
> your case, you only need to synch TWO laptops, and I infer from your comment
> that there's a WiFi link between your laptops.  The most prevalent
> synchronization protocol, NTP, ships with every machine and will get you
> within 1mS synchronization on a local area network.
>
> But the question on my mind: do you REALLY need sample accurate synch?
>  Sound travels 34 centimeters in 1 millisecond -- you incur that kind of
> timing error just by moving your speaker by a foot.  The only case where I
> could imagine that sample accurate synch is really important is when you are
> trying to divvy up a four channel sound file among two machines in which
> case the phase relationship among the channels is important.
>
> But in any other situation, I'd invest the time in getting ChucK to slave
> to the system clock and simply let NTP synch multiple machines -- that part
> is already done.
>
> Let me know what you find.
>
> - Rob
>
>
> On 27 Jan 2009, at 17:04, Stephen Sinclair wrote:
>
>  I don't know about ChucK's support for OSC bundles, but if you send a
>> clock signal with explicitly timestamped OSC bundles it should be
>> possible to find a constant delay for each receiving computer and get
>> pretty good synchronization.  I haven't tried this myself however.  It
>> would definitely be an interesting exercise.
>>
>> Steve
>>
>>
>> On Tue, Jan 27, 2009 at 7:39 PM, kevin <vacillates at gmail.com> 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<http://music.princeton.edu/%7Edan/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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