[PD] [writesf~] sample rate problem?

Roman Haefeli reduzierer at yahoo.de
Tue Jul 3 10:27:33 CEST 2007


hi tim again

i just noticed, that we have been talking off-list during this thread. i
post that to the list again (it might be interesting for others as
well).

what you describe, shouldn't happen. if you use '-rate 96000', as
mentioned in the help file of [writesf~], and the files still have
'44100' in their headers, then it is definitely a bug of pd,
respectively [writesf~]. i'm too lazy to test it now and here with
aiff-files (you are writing to aiff-files, right?).

yo, i only know how to fix the sampling rate header field  in wav-files,
not in aiff-files unfortunately. the rate is written in the bytes 24-27
(when counting from 0) or in hex 0x00000018 -> 0x0000001B:

you will find there:

44 AC 00 00

(0x0000AC44 = 44100)

change this to:

00 77 01 00

(0x00017700 = 96000)

maybe it works similar for aiff-files, but i don't know.

roman





On Mon, 2007-07-02 at 16:44 -0400, Tim Flood wrote:
> Hi Roman-
> 
> Yes, that is it: the audio files sound pitched/slowed down.  When I
> open them in another application (soundhack, quicktime, etc.), they
> are always listed at 44.1k.  So maybe PD is in fact RECORDING at 96kHz
> but for some reason the header has the wrong sr, as you suggested.  I
> haven't used hex editors in the past, but will look into it as a means
> of fixing this problem.  
> 
> Thanks again,
> 
> -Tim
> 
> 
> 
> 
> 
>         
>         ______________________________________________________________
>         
>         From:  Roman Haefeli <romanhaefeli at yahoo.de>
>         Reply-To:  romanhaefeli at yahoo.de
>         To:  Tim Flood <timflood23 at hotmail.com>
>         Subject:  Re: [PD] [writesf~] sample rate problem?
>         Date:  Mon, 02 Jul 2007 02:37:14 +0200
>         >hm.......wierd.... i don't have a solution at hand for this.
>         but you
>         >could do some checks. to make sure, that pd _really_ runs at
>         96kHz,
>         >check that with the object [samplerate~]. it should output
>         '96000' on
>         >'bang', when pd runs at this rate. if so, than i would
>         assume, that the
>         >resulting files _are_ recorded with 96kHz, since it is pretty
>         sure, that
>         >[writesf~] does not do any conversion.
>         >if pd runs at 96kHz and the resulting files don't sound
>         pitched down,
>         >then i really wonder, what makes you think, they have a
>         sampling rate of
>         >44.1kHz.
>         >if the resulting files sound pitched down, then it probably
>         is a header
>         >issue (wrong sr tag in the header). this could be easily
>         fixed with the
>         >help of a hexeditor.
>         >
>         >yo, i hope that can help you isolate your problem a bit.
>         >
>         >roman
>         >
>         >
>         >
>         >On Sun, 2007-07-01 at 20:13 -0400, Tim Flood wrote:
>         > > Hello Roman-
>         > >
>         > > Thank you for your quick response.  Yes, my soundcard (a
>         MOTU Ultralite
>         > > firewire interface) is set up to use a sampling rate of
>         96kHz.  The "clock
>         > > source" is set to internal. I have included a "-r 96000"
>         flag in my startup
>         > > preferences.  Still, every file is written at 44.1kHz.  I
>         am running
>         > > Hans-Christoph Steiner's latest version of Pd-extended on
>         Mac OS 10.4.  If
>         > > you think of any other possible causes for this problem,
>         please drop me a
>         > > line....
>         > >
>         > > Best Regards,
>         > >
>         > > -Tim
>         > >
>         > >
>         > >
>         > > >From: Roman Haefeli <romanhaefeli at yahoo.de>
>         > > >Reply-To: romanhaefeli at yahoo.de
>         > > >To: Tim Flood <timflood23 at hotmail.com>
>         > > >CC: pd-list at iem.at
>         > > >Subject: Re: [PD] [writesf~] sample rate problem?
>         > > >Date: Mon, 02 Jul 2007 00:49:55 +0200
>         > > >
>         > > >sorry, i was inaccurate. there *is* a '-rate' flag, but
>         it doesn't cause
>         > > >any conversion. as the help file states, it just affects
>         the samplerate
>         > > >entry in the header of the soundfile. this is probably
>         not what you
>         > > >want. therefore it is still worth reading my previous
>         mail.
>         > > >
>         > > >roman
>         > > >
>         > > >
>         > > >On Mon, 2007-07-02 at 00:40 +0200, Roman Haefeli wrote:
>         > > > > hello tim
>         > > > >
>         > > > > there is no '-rate' flag for [writesf~], since it
>         doesn't do any
>         > > > > sampling rate conversion. it just uses the sampling
>         rate of pd. it
>         > > > > wouldn't make much sense to upsample for recording
>         (e.g. 44100 ->
>         > > > > 96000Hz) anyway.
>         > > > >
>         > > > > in other words: you need to run pd at the desired
>         samplerate. if you
>         > > > > want to record with 96000Hz, run pd with '-r
>         96000'.  BUT this still
>         > > > > doesn't always guarantee, that pd will effectively run
>         with the desired
>         > > > > sampling rate. sometimes it is needed to set the clock
>         of the audio card
>         > > > > to the desired rate by the preferences menu of the
>         soundcard (sometimes
>         > > > > the application just changes the samplingrate setting
>         of the card on the
>         > > > > fly).
>         > > > > for example on my system, when i want to record at
>         96kHz, i need to set
>         > > > > my hdsp-card to 96kHz, so that jackd runs at 96kHz, so
>         that pd runs at
>         > > > > 96kHz, so that i can record in pd with 96kHz. got it?
>         > > > >
>         > > > > if that doesn't help you already, please tell us, on
>         what os you work
>         > > > > and which soundcard/driver you use.
>         > > > >
>         > > > > roman
>         > > > >
>         > > > >
>         > > > > On Sun, 2007-07-01 at 17:42 -0400, Tim Flood wrote:
>         > > > > > Hello Everyone-
>         > > > > >
>         > > > > > I have written a simple patch (see below) designed
>         for hard disk
>         > > >recording
>         > > > > > at 24-bit/96kHz.  The -bytes flag sets the bit depth
>         correctly, but no
>         > > > > > matter what value I use to set the -rate flag, the
>         file is always
>         > > >created
>         > > > > > with a sampling rate of 44.1kHz.  (My soundcard is
>         set up to work at
>         > > >96kHz).
>         > > > > >   Is this a bug, or am I just missing
>         something?  Any help would be
>         > > >greatly
>         > > > > > appreciated!
>         > > > > >
>         > > > > > Best Regards,
>         > > > > >
>         > > > > > -Tim
>         > > > > >
>         > > > > > #N canvas 224 44 449 382 10;
>         > > > > > #X msg 129 286 start;
>         > > > > > #X msg 198 286 stop;
>         > > > > > #X obj 43 336 writesf~ 2;
>         > > > > > #X obj 153 71 time;
>         > > > > > #X obj 16 173 pack s s s s s s;
>         > > > > > #X obj 16 96 makefilename %u;
>         > > > > > #X obj 26 147 makefilename %u;
>         > > > > > #X obj 153 96 makefilename %u;
>         > > > > > #X obj 161 122 makefilename %u;
>         > > > > > #X obj 169 147 makefilename %u;
>         > > > > > #X obj 16 71 date;
>         > > > > > #X obj 21 122 makefilename %u;
>         > > > > > #X obj 43 260 inlet~;
>         > > > > > #X obj 100 260 inlet~;
>         > > > > > #X obj 129 336 print record;
>         > > > > > #X text 123 173 time & date stamp;
>         > > > > > #X text 10 4 [diskRecorder~];
>         > > > > > #X text 13 18 writes an audio file to disk.;
>         > > > > > #X text 43 244 main-l;
>         > > > > > #X text 101 244 main-r;
>         > > > > > #X obj 16 50 bng 15 250 50 0 empty empty empty 0 -6
>         0 10 -262144 -1
>         > > > > > -1;
>         > > > > > #X text 231 223 open 24-bit/96kHz file;
>         > > > > > #X msg 16 224 open -rate 96000 -bytes 3 -aiff \$1;
>         > > > > > #X obj 16 198 makesymbol %s-%s-%s_%s-%s-%s;
>         > > > > > #X text 36 48 push me;
>         > > > > > #X connect 0 0 2 0;
>         > > > > > #X connect 0 0 14 0;
>         > > > > > #X connect 1 0 2 0;
>         > > > > > #X connect 1 0 14 0;
>         > > > > > #X connect 3 0 7 0;
>         > > > > > #X connect 3 1 8 0;
>         > > > > > #X connect 3 2 9 0;
>         > > > > > #X connect 4 0 23 0;
>         > > > > > #X connect 5 0 4 0;
>         > > > > > #X connect 6 0 4 2;
>         > > > > > #X connect 7 0 4 3;
>         > > > > > #X connect 8 0 4 4;
>         > > > > > #X connect 9 0 4 5;
>         > > > > > #X connect 10 0 5 0;
>         > > > > > #X connect 10 1 11 0;
>         > > > > > #X connect 10 2 6 0;
>         > > > > > #X connect 11 0 4 1;
>         > > > > > #X connect 12 0 2 0;
>         > > > > > #X connect 13 0 2 1;
>         > > > > > #X connect 20 0 3 0;
>         > > > > > #X connect 20 0 10 0;
>         > > > > > #X connect 22 0 2 0;
>         > > > > > #X connect 23 0 22 0;
>         > > > > > #X connect 23 0 14 0;
>         > > > > >
>         > > > > >
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