RE: Staff and voice definitions

[Trevor Daniels]

David

I take your points about the maths analogies.  They
clearly only serve to confuse anyone not familiar
with maths.  Thanks for this, and your other comments
on the Learning Manual.  I'll certainly bear them in 
mind when I next edit that section and try to clarify
the words there.

Perhaps the hardest LilyPond concept to understand 
is the use of double angle brackets - <<..>>.  

Things contained within a brace {..} are sequential;  
things contained within double angle brackets 
<<..>> are concurrent (for historical reasons 
LilyPond uses the term 'simultaneous' to mean
'concurrent'.)  So to stack Staves into a system they
must be placed within <<..>> as they music they contain
must be played concurrently; to stack Voices within
a Staff they must be within <<..>> for the same reason.

Multiple voices are only needed if there are notes
within the same staff which need to sound concurrently
but which start and/or end at different times; otherwise
using single angle brackets <..> to indicate chords is
adequate.

I'm not familiar with your specific example, but I
understand your difficulty.  A similar situation
arises in CPE Bach's "Solfeggettio" with a single
melody running through both hands and staves.  Below
I show how to write the first two bars of this piece in
two different ways.  Try compiling both of them to see 
what they look like.

1) Splitting the melody into the two staves and
using skips to step over the periods when the
melody is in the opposite hand:

\score {
  \new PianoStaff <<
    \new Staff = "RH" <<
      \key c \minor
      \relative c' {
        s4 c16 ees d c s4 g'16 f ees d |
        \stemDown ees16 c ees g
        \stemUp c16 ees d c d c b a g f ees d |
      }
    >>
    \new Staff = "LH" <<
      \clef "bass"
      \key c \minor
      \relative c {
        ees16 c ees g s4 b16 g b d s4 |
        s4*4
      }
    >>
  >>
}

2) Coding a single melody line and using \change
to switch this between staves.  I've never used
this before and I found this quite tricky to do,
for the reasons I've placed below the example.  If
Mats or anyone else can improve on how to use
\change for this example or correct any misconceptions
in the comments below I'm sure we'd both be grateful.  
First the same example coded this way:

\score {
  \new PianoStaff <<
    \new Staff = "RH" <<
      \key c \minor
      \skip 1*2
    >>
    \new Staff = "LH" <<
      \clef "bass"
      \key c \minor
      \relative c {
        ees16 c ees g
        \change Staff = "RH" c ees d c
        \change Staff = "LH" b g b d
        \change Staff = "RH" g f ees d |
        \stemDown ees c ees g
        \stemUp c ees d c d c b a g f ees d |
      }
    >>
  >>
}

and now some comments.  The melody -must- be placed
in the lowest staff, because the references in the
\change statement can refer only to staves which
have already been defined earlier.  This also means 
the music cannot be placed in a variable, as that
has be be defined before it is used, and both
cannot be satified simultaneously.  Also the
\skip in the first staff is -required- if there is
no other music on that staff, otherwise
the staff no longer exists when it is needed as the
melody switches to it.  The skip has to be as long 
as the music, here just 2 bars. 

HTH a bit

Trevor D


> -----Original Message-----
> From: David Fedoruk [mailto:address@hidden
> Sent: 25 December 2007 07:16
> To: address@hidden
> Cc: Lilypond mailing list
> Subject: Re: Staff and voice definitions
> 
> 
> Hello
> 
> > You don't say which version of LilyPond you are 
> using, but I'm sure the answers to your questions 
> are contained in the documentation which came with it.
> 
> I am using 2.11.35
> 
>   Alternatively, you may find the answers in the 
> documentation being
> prepared for release 2.12, which can currently be 
> found under the 2.11
> development pages.  To be more specific, look at 
> chapters 2 and 3 in
> the Learning Manual at
> http://kainhofer.com/~lilypond/Documentation/user/
> lilypond-learning/index.html.
>  These explain the concepts of Staff and Voice.  
> I'd be interested to
> hear if they help.
> 
> Yes, I had read that documentation and that was 
> what prompted my
> questions as well as the project I am currently 
> working on.
> 
> 2.3.1 Musical Expressions Explained.
> 
> The illustration of { {  a4 g }  fg} as rendered 
> in sequence is
> understandable, but the minute you used a 
> mathematical analogy, you
> lost me completely. It only complicated things for me.
> 
> polyphony:
> 
> Am I correct in assuming that it is <<>> that 
> tells lilypond that it
> is polyphonic? Although I know how they are used, 
> I have never known
> exactly what they mean.
> 
> In my mind, polyphony and the number of staves 
> are not linked
> concepts. One does not depend or imply the other. 
> The number of staves
> (to me) is merely for the convenience of the 
> performers. So before
> using lilypond, I didn't consider that piano 
> music was mostly 4 part
> polyphonic writing. I saw it as two handed -- two 
> part. I then
> considered the possibility of single voiced piano 
> writing using two
> hands. I hadn't thought that two hands might be 
> playing one part
> between them.
> 
> 2.3.2
> 
> "These Staff elements are then combined in 
> parallel with << and >>"
> 
> The last sentence describes what happens *after* 
> the \new staff is
> created. So they are created in parallel| f with 
> ... what if there are
> no << >> because there is no polyphony happening? 
> Consider this
> passage of piano music. I have only given two 
> bars, but it continues
> like this for 24 bars with no simultaneous notes. 
> It is not
> polyphonic, though it is divided between two 
> hands as originally
> written and as it is performed. In the score, 
> right and left hands are
> indicated completely by stem direction and not by 
> presence or absence
> on either staff (there is treble and bass clefs 
> in the original). So
> the clefs and staves are for ease of reading. The 
> right hand has the
> first beamed group, the left hand alternates with 
> it after that. For
> the sake of this question, I have not put this in 
> a piano staff
> context, though that is where it will ultimately 
> reside. The previous
> section has two voices, this B section is single voiced.
> 
> Schumann Kreisleriana opus 16 number 1 bar 25
> 
> \relative c''
> \key d \minor
> \clef treble
> \time 2/4
> trip = \times 2/3  % this may not be the correct 
> way to crete this variable
> g''16 | trip {f''[ bf' ] d'' } trip { f,[ bf' ] 
> ef''  } trip { d''[ f,
> ] bf } trip { d'',[ bf, ] d'' } | trip { c''[ f', 
> ] gf' } trip { ef'[
> bf, ] d'' } trip { ef''[ f' ] g' } trip { ef'[ 
> bf, ] d'' } |
> 
> This is the passage which prompted me to ask the 
> quetsion after
> reading the documentation. If this is polyphonic, 
> then there must be
> staff changes and rests or hidden rests. If not, 
> then there are no
> rests and no need for staff changes even if there 
> are two staves
> present. In the score there are no rests 
> indicated where one hand is
> silent, so it is really a single voice.
> 
> This puzzles me:
> 
> "In terms of syntax, prepending \new to a music 
> expression creates a
> bigger music expression. In this way it resembles 
> the minus sign in
> mathematics. The formula (4+5) is an expression, 
> so -(4+5) is a bigger
> expression. "
> 
> Arithmetically 4+5 = 9 AND (4+5) = (9)
>                         -(4+5)= -(9) = -9
>                       
>                         Or
> Do you mean that the expression -(4+5) has more 
> elements in it (that
> is 6 elements) where (4+5) has only 5 elements in it?
> 
> Have I missed something here?
> 
> 2.3.3
> 
> "Piano music is typeset in two staves connected 
> by a brace. Printing
> such a staff is similar to the polyphonic example 
> in Multiple staves.
> However, now this entire expression is inserted 
> inside a PianoStaff: "
> 
> A point of confusion is what creates the 
> polyphonic character, the
> brace or the <<>>? Would it be monophonic writing 
> without the << >>?
> Or would Lilypond simply be confused.
> 
> I think many of my questions arise from the 
> divide between thinking of
> a programmer and that of a non-programmer. I have 
> read music for so
> long that I no longer think about how I 
> understand it, I simply read
> it like you would read a book. So when I come to 
> working with
> Lilypond, I have to re-examine many of these 
> things. I don't think
> about English grammar when I read or write and 
> often I may not even
> completely understand my own grammatical choices. 
> I may not  even why
> my sentence construction is correct.
> 
> -- 
> David Fedoruk
> B.Mus. UBC,1986
> Certificate in Internet Systems Administration, UBC, 2003
> 
> 
> http://recordjackethistorian.wordpress.com
> "Music is enough for one's life time, but one 
> life time is not enough
> for music" Sergei Rachmaninov
>