[PD] Audio drops when I refresh many text in scrolline by externalMIDI control.

Phil Stone pkstone at ucdavis.edu
Fri Oct 19 16:33:57 CEST 2007


I was working on a similar problem last weekend (see 
http://lists.puredata.info/pipermail/pd-list/2007-10/055005.html for the 
thread).  If your problem is related to file i/o, and I think it might 
be, then any i/o that takes longer than one dsp block to complete will 
cause audio dropouts.

The good news is that you don't have to manually load everything into 
memory to avoid this; I had good success using a ram disk.  This is 
better than pre-loading everything because your code doesn't have to 
change -- it still thinks it's loading from a hard drive.  On OS X, at 
least, there are utilities that make setting up ram disks very easy 
(even allowing automatic read/write from disk for automatic 
persistence).  Even without utilities, it's not hard to do on *nix (I 
don't know about Windows).

In many cases (all my cases), the ram disk speeds up the i/o enough to 
get things done in one DSP block -- thus, no dropouts.

I hope this can help you.

Phil Stone

Kuba Szczypek wrote:
> Thank you Derek,
> Two instances I alerady tried, but sending by osc that many messages 
> give me the same result (so it isn`t problem with scrollist).
> Of course I can put all modules/objects/patch related to 
> keeping_song_names_in_memory and putting_this_names_to_scrollist
> on second instance, but this is serious complicating life.
> Question: Of course we all love PD, but is this system only for 
> learning? If I need to build good, stabillity, without any drops in 
> audio (also when I read or write to disk) patch for have fun from 
> playing/creating music - is puredata good choice or it`s better jump to 
> another environment (like max)?
> I`m open to change since most important for me is finally finish project 
> with great result, and not waiting for update.
> -rt flag I have all time, and running under root give no difference.
> If I good understand jack adding latency?
> thank you
> Kuba
> Dnia 19-10-2007 o godz. 13:48 Derek Holzer napisał(a):
>> Hi Kuba,
>> same problem as ever.... PD's GUI implementation is a bit crippled. My
>> suggestion would be to run two instances of PD, one for the DSP running
>> --nogui and one for the GUI running --noaudio. Communicate between via
>> netsend or OSC. Check the archives for more tips on this.
>> As a workaround, you could also try a single instance of PD, running -rt
>> as root. This cleared up some but not all of my GUI-related glitches on
>> Linux.
>> My experiences were that ALSA+JACK worked best, but others (like Frank
>> Barknecht) have reported that OSS (by this I assume OSS emulated by
>> ALSA) worked better, or at least as good. I think. Again, search the
>> archives, because that topic comes up very often on this list.
>> best,
>> d.
>> Kuba Szczypek wrote:
>>> Dear friends,
>>> I have serious problem with  my patch. It is hard to write it in proper
>>> English for me, but I have no choice - I must try,since I`m looking for
>>> help.
>>> I would like to show (by scrollist) my list of titles 128 song names.
>>> But since I have small space for this on screen, I use only 8 lines in
>>> scrollist and "page up" page down" mechanism.
>>> I prepared patch who:
>>> - first send 128 lines into memory of scrollist
>>> - next I mark/unmark proper line.
>>> But since I have only 8 line show  on display , and list have 128
>>> positions I often must change pages.
>>> The problem is that changing pages cause drop. If I change very fast (by
>>> fader) from 0 to 127 (song nuber) many times and from 127 to 0 (again
>>> again) then I can see that screen is completely frozen and audio drop is
>>> very long (like about 3, 4 second).
>>> More moving I did = bigger drop and longer frozen screen.
>>> When I do the same, but with fader on the screen, no problem there.
>>> Problem is only when I use external MIDI fader.
>>> (of course normally when I use any MIDI message it work great,
>>> problem is only with this setup: scrollist)
>>> I tried change thread priority (pd and pd-gui) with many different
>>> combinations, but it not solved problem.
>>> I use Ubuntu Studio with gnome, oss audio system. Pentium IV 2,4  512
>>> ram Geforce mx 400 with TV out enabled.
>>> I would like to ask also is oss better than alsa+jack or not?
>>> (I mean performance power).
>>> Thank you
>>> ----------------------------------------------------
>>> Paul Oakenfold - najdroższy DJ świata
>>> już 7 grudnia wystąpi w Hali Stulecia we Wrocławiu.
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>> --
>> derek holzer ::: http://www.umatic.nl :::
>> http://blog.myspace.com/macumbista
>> ---Oblique Strategy # 175:
>> "What are the sections sections of? Imagine a caterpillar moving"
> ----------------------------------------------------
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