[LAU] [LAA] Qtractor 0.1.3 (frugal damsel) released!

[Mark Knecht]

On Sat, May 3, 2008 at 11:04 AM, Mark Knecht <markknecht at gmail.com> wrote:
>
> On Sat, May 3, 2008 at 7:12 AM, Rui Nuno Capela <rncbc at rncbc.org> wrote:
>  >
>  > Pieter Palmers wrote:
>  >
>  > > Rui Nuno Capela wrote:
>  > >
>  > > > Mark Knecht wrote:
>  > > >
>  > > > > On Fri, May 2, 2008 at 12:21 PM, Rui Nuno Capela <rncbc at rncbc.org>
>  > wrote:
>  > > > >
>  > > >
>  > >
>  > > [...]
>  > >
>  > >
>  > > >
>  > > > > As for edge dragging, in Acid this allows you to play a portion of a
>  > > > > loop. If I place a loop in a session the tempo is adjusted
>  > > > > automatically and I hear the whole loop. If I drag the left edge to
>  > > > > the right I lose the front part of the loop. If I drag the right edge
>  > > > > to the left I lose the last part of the loop. There are ways to drag
>  > > > > the loop to an out-of-sync point if you want but I don't use it much,
>  > > > > really only for beat slicing where they have better tools in the
>  > > > > editor.
>  > > > >
>  > > > >
>  > > >
>  > > > when you import (or drop) a new audio file into the qtractor time-line,
>  > it's always assumed that the new clip is in tempo with the current session.
>  > if you find it is not the case, you can trim and/or (time-)stretch the clip
>  > until you see fit. take a tour:
>  > > >
>  > >
>  > > [...]
>  > >
>  > > As far as I can remember, the "automagic-ness" of ACID relies on some sort
>  > of extra metadata. I think it was embedded in the WAV file, but it might
>  > have been somewhere else.
>  > >
>  > > The point is, if there is such metadata in a clip (e.g. wav), why no use
>  > it? Have an option like "strech clip according to tempo metadata" or the
>  > likes. If I remember your LAC presentation correctly, all resampling is done
>  > "on-the-fly" (modulo some cacheing) so isn't is simply initializing the
>  > 'stretch factor' to a proper value?
>  > >
>  > > 2cents for the masses,
>  > >
>  > >
>  >
>  >  that's a good point indeed. i do remember that Mark has aslo referred to me
>  > about the meta-data acid do stuff into wavs, but i'm afraid i've lost the
>  > hint at the bottomless qtractor todo list ;)
>  >
>  >  question that occurs to me atm. might be: does libsndfile have the means to
>  > read or access that meta-data ?
>  >
>  >  as said, implicitly, i don't nor ever used acid, but it might be of some
>  > help if someone would hand out one of the acid-stuffed wavs for me to try?
>  >
>  >  cheers
>  >  --
>  >  rncbc aka Rui Nuno Capela
>  >  rncbc at rncbc.org
>  >
>
>  Short answer, yes, sort of...
>
>  I don't remember what app it is and I'm not in Linux at the moment but
>  I think it might be sndfileinfo has the ability to read a lot of the
>  meta-data. Problem was whomever I worked on this with 5 years ago (I
>  think it was Erik in those days but please don't let my bad memory
>  tarnish his reputation) ran out of time/interest and only got part of
>  the work done. Fortunately what he did get done was apparently
>  accurate so at least it's a good start. I do see that libsndfile lists
>  reading loop data as added in Nov., 2004 but I know I worked on it
>  earlier than that.
>
>  Anyway, when you find the right app and you download a few 'Acidized'
>  loops from the ACIDPlanet site for free you'll find that the info
>  tells you not only tempo & key but it also gives the author, library
>  name and probably most interesting, trimming information. Apparently
>  many Acid loops have a bit of a leader and trailer in the file. It's
>  my suspicion that the loop author suggests where to start and stop
>  playing, thus synchronizing the loop's natural beats with the measure
>  bars in the session. A few samples before and after thus allow for
>  some automatic fade-in/fade-out, etc., without everything being so
>  abrupt. That's all guessing on my part though.
>
>  I think the important issue here is that not ever Acid loop has
>  exactly the right number of samples to equal tempo. Doing some
>  calculations:
>
>  60 BPM is 1 beat/sec. Assuming a 4/4 time signature and a 1 measure
>  loop then the loop's sound be 4 seconds long. 4 seconds of 44.1KHz
>  audio would suggest 176,400 16-bit samples. (Per channel) When you
>  look at the actual length it may be 178,000 or 180,000 with trim
>  information to suggest where to play from and to.
>
>  The issue (I think) is that if you just played the whole loop, from
>  first sample to last, then the playback wouldn't be identical to the
>  way the loop author hears it on a system that honors this start/end
>  data. Close, but not identical.
>
>  Hope this helps, and again, all credit to those who build these wonderful toys.
>
>  Cheers,
>  Mark
>

Here's a couple of examples of sndfile-info looking at Acid loops. The
first is a drum loop, the second a promo I got off of AcidPlanet this
morning. There are certainly tempo problems with both of these as
neither loop is 120BP natively but remember it was a work in progress
where progress stopped and not that anyone said the work was done...

- Mark

mark at lightning ~/Desktop/My Data/Music/072 BPM (Slow Groove) $
sndfile-info Fill1.wav

Version : libsndfile-1.0.17

========================================
File : Fill1.wav
Length : 441654
RIFF : 441646
WAVE
fmt  : 16
  Format        : 0x1 => WAVE_FORMAT_PCM
  Channels      : 2
  Sample Rate   : 44100
  Block Align   : 6
  Bit Width     : 24
  Bytes/sec     : 264600
data : 440934
acid : 24
  Flags     : 0x0000 (Loop,RootNoteInvalid,StretchOff,RAMBased,??Off)
  Root note : 0x3C
  ????      : 0xFFFF8000
  ????      : 0.000000
  Beats     : 2
  Meter     : 4/4
  Tempo     : 120.000008
strc : 636
End

----------------------------------------
Sample Rate : 44100
Frames      : 73489
Channels    : 2
Format      : 0x00010003
Sections    : 1
Seekable    : TRUE
Duration    : 00:00:01.666
Signal Max  : 7.23123e+06 (-1.29 dB)

mark at lightning ~/Desktop/My Data/Music/072 BPM (Slow Groove) $


mark at lightning ~/Desktop/My Data/Music/Painting After Hours $
sndfile-info AFTERHOURS\ EDM\ pahPROMO\ 01.wav

Version : libsndfile-1.0.17

========================================
File : AFTERHOURS EDM pahPROMO 01.wav
Length : 2619310
RIFF : 2619302
WAVE
fmt  : 16
  Format        : 0x1 => WAVE_FORMAT_PCM
  Channels      : 2
  Sample Rate   : 44100
  Block Align   : 4
  Bit Width     : 16
  Bytes/sec     : 176400
data : 2605292
acid : 24
  Flags     : 0x0002 (Loop,RootNoteValid,StretchOff,RAMBased,??Off)
  Root note : 0x36
  ????      : 0xFFFF8000
  ????      : 0.000000
  Beats     : 32
  Meter     : 4/4
  Tempo     : 120.000000
strc : 4636
*** str2 : 20 (unknown marker)
*** bmrk : 7024 (unknown marker)
*** dtbt : 520 (unknown marker)
LIST : 82
  INFO
    *** MRAT : 4
    ICOP : (c) 2008 Sony Creative Software Inc. All rights reserved.
*** mudp : 1612 (unknown marker)
End

----------------------------------------
Sample Rate : 44100
Frames      : 651323
Channels    : 2
Format      : 0x00010002
Sections    : 1
Seekable    : TRUE
Duration    : 00:00:14.769
Signal Max  : 32735 (-0.01 dB)

mark at lightning ~/Desktop/My Data/Music/Painting After Hours $