[chuck-users] Audio Range and Zero-crossings, Performance, Hashes and Future DIrections
ssalazar at CS.Princeton.EDU
Sun Mar 4 14:16:45 EST 2007
Welcome to ChucK!
On Mar 4, 2007, at 8:30 AM, Veli-Pekka Tätilä wrote:
> 1. What's the range of the audio float datatype and what would be
> the best
> way to detect zero crossings?
> I'm assuming here that samples are floats or doubles from -1 to 1 as
> in VST, as I didn't find the range in the manual. Is this correct?
Yes. Although, the -1 to 1 part isn't enforced within a UGen graph,
so a system that is dealing with completely arbitrary input probably
shouldn't have that expectation.
> 3. Is there any way to decrease the latency on WIndows platforms
> for true
> realtime MIDI playback and audio processing similar to Reaktor?
> latency is pretty bad as my audio machine, which isn't this laptop,
> have both WDM kernel streaming and ASIO support in it.
You could try decreasing the audio buffer size through the --
bufsize### command line option (see http://chuck.cs.princeton.edu/doc/
program/vm.html for more information). However, please note that
smaller buffer sizes may cause audio to break up, depending on your
soundcard, audio driver, and OS.
> 4. How does one use the ZeroX module for detecting zero crossings?
> the value range and what is the output method of that module called
> which thing should I poll to detect the crossings?
> The manual says:
> Emits a single pulse at the the zero crossing in the direction of
> the zero
Yes--this just means that for a zero crossing from > 1 to < 1 in its
input, it outputs a -1 for that particular sample, and for < 1 to >
1, it outputs a 1.
> 6. How do you use the array datatype in ChucK as a hash? I read
> that you can
> index the array with strings much like a Perl hash, except that
> numbres and
> strings are totally separate. If I get handed a hashtable whose
> keys I don't
> know beforehand, is there a keys or each function for iterating
> through the
> hash's keyset? Is the hash portion of the array unordered as one might
> expect in an implementation e.g. an array of pointers to linked-lists?
The hash table form of arrays is somewhat limited in available
operations at this time--its only possible to do assignment and
lookup, with keys that are known in advance. Clearly we'd like to
have some more advanced functionality built into hash tables in the
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