[PD] file access audio glitches

[Roman Haefeli]

hi phil

afaik, this affects every pd (yet) on every os, since this is due to
pd's design. all objects i know, that do fileIO (except the threaded
soundfiler), do block pd's processing until they will have finished
their task. if you have something like this:

[t b b]
|     |
|     [read somefile(
|     | 
|     [somefilereadingobject]
|
[print]

the bang will be printed only after [somefilereadingobject] has finished
reading the file. you are probably going to say, that this is odd, but
that is how pd actually/unfortunately works.

the only way to overcome this issue (beside rewriting pd or writing new
objects) is to put everything into ram in advance. i don't know, what
kind of files you are reading, but there are quite a few objects, that
can read and store textfiles, as there are quite many for soundfiles as
well. 

if you really don't know in advance, which file you are going to open,
then you could probably build some kind of an 'asynchronous' filereader
patch, that runs in another (-nrt) instance of pd, that passes the data
over a network socket ([netsend]/[netreceive]) to your audio
patch/instance. beware, that [netsend] is not dropout safe as well, but
as long as you only have the [netreceive] in your audio patch, this
won't be an issue.

roman

p.s.: it's probably the right moment now to mention, that the nova
project addresses such issues.   



On Sat, 2007-10-13 at 12:02 -0700, Phil Stone wrote:
> Hi everybody,
> 
> I'm not even certain this is a problem across all operating and sound 
> systems; it certainly is a problem on my setup with OS X.  Any sort of 
> file access has the possibility (*probability* on the first access to a 
> given file) of causing audio dropouts.  For instance, if I use [tunetof] 
> to load in new scale data, the first time I access a given scale file, 
> there's a dropout.  Subsequent accesses of that same file don't seem to 
> cause dropouts.
> 
> I currently just switched to PD 0.40.3-extended, but this has been 
> happening for as long as I can remember -- several versions back.
> Is this behavior common across PD, or just something intrinsic to OS X 
> or my sound hardware?
> 
> Also, is it some kind of file caching that's keeping subsequent access 
> to a file from causing dropouts?
> 
> 
> Phil Stone
> pkstonemusic.com
> 
> 
> 
> _______________________________________________
> PD-list at iem.at mailing list
> UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list


		
___________________________________________________________ 
Telefonate ohne weitere Kosten vom PC zum PC: http://messenger.yahoo.de