[PD] How to navigate a long sound file in vanilla PD

William Huston williamahuston at gmail.com
Tue Mar 31 17:07:52 CEST 2015

I have a related question.

I am intermediate PD programmer, about 9 months into patching.
I really love PD, despite some quirks.

The single most annoying issue I have found so far is the inability for PD
to accurately index into large arrays.

The way this manifests is very curious! I first noticed high frequency
noise at maybe 6 min. into an array, which gets worse as you move into the
file. At 20 min, it's really horrible.

I would say the root cause is

a) lack of a long integer datatype. Friends, sometimes you really want
ints, like accurately indexing into an array, and

b) lack of precision in (short) floats.

People on the FB group promptly told me this is a well-known issue, and
directed me to PD-double. This sounds like a wonderful project, however it
seems it is only beta, and breaks several of the modules in extended.

So I am wondering 2 things:

1) What solutions have people come up with for accurately reading big
arrays at audio rate, using either pd-extended or vanilla?

(I have considered breaking the big file up into smaller arrays, but this
is cumbersome).

2) What is the long-term goal at solving this problem?

Thanks :)

On Tue, Mar 31, 2015 at 5:51 AM, peiman khosravi <peimankhosravi at gmail.com>

> Sorry, forgot to reply to all.
> Hello,
> I had this problem in maxMSP recently and found a working solution. Note
> that I was only on a laptop so I don't know how relevant this is to your
> question. Below is the solution I found on the Max forum (I don't have the
> link right now but it should come up on google).
> 1- Read the file [silently] from disk (using sfplay~ or equivalent), at 50
> times the original speed and record the output into a buffer that is 50
> times smaller than the original file.
> 2- You can navigate through this smaller buffer and multiply the output by
> 50 to get the correct time pointer into the original file. I then read the
> original file from the disk, instead of loading it into a buffer.
> 3- Since I'm making my patch for concert playback, I have put in place a
> checking mechanism that looks for an existing 'waveform' file. (The patch
> automatically names these originalFileName.wave.aif.) If it exists, the
> waveform file is read into the buffer, otherwise, the loaded soundfile is
> 'analysed'.
> I can send you my patch if you are interested. I don't see any reason why
> this can't be implemented in PD. Although the graphical scrolling might be
> slower in PD. I'd be interested to know if this works in PD.
> Best,
> Peiman
> *www.peimankhosravi.co.uk <http://www.peimankhosravi.co.uk> || RSS Feed
> <http://peimankhosravi.co.uk/miscposts.rss> || Concert News
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> On 31 March 2015 at 10:18, Stefan Tiedje <stefantiedje at googlemail.com>
> wrote:
>> Hello list,
>> might well be the first post here, though I am well experienced in
>> Max/MSP...
>> As there is no way to get Max patches run on mobile devices, I want to do
>> it in PD using the MobMuPlat apps for Android/iOS.
>> The task would be to simply to play a stereo sound file, but of about one
>> hour lebgth. As MobMuPlat only supports vanilla PD I am restricted to that
>> as far as I know.
>> In the docs and on the net I did not find any way to navigate within that
>> playback. (Its crucial for rehearsals.) The size is too big for loading it
>> into RAM (the mobile devices which are around often have less than 1 GB of
>> RAM), Is there a known way to tackle this seemingly simple task???
>> A tedious way, I want to avoid, would be to split the sound file into
>> pieces, which would at least let me jump in at specified places, but that
>> would eat up the space on the device, as each piece would have to play
>> until the end...
>> Of course I would also love to find a way to play back an mp3 and freely
>> navigate within that as well...
>> Any hints how to proceed are appriciated...
>> Stefan Tiedje
>> --
>> Les Ondes Memorielles--------x--
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