Re: MIDI Tempo Off...Everywhere

[Mats Bengtsson]

Thanks for the analysis.

I haven't contributed with many lines of code to LilyPond, but I'm
afraid I might be the culprit for this problem. I just found a copy
of a patch I submitted in summer 1999 where I removed the tempo setting
in track 0.

The reason was that I introduced support for tempo changes in the
middle of a piece and did this by adding tempo changing commands in
the track corresponding to the stave where the tempo change was
specified. This worked well with all the MIDI sequencers I had
access to. The only problem was that different sequencers read the
tracks in different order so if you had one \tempo declaration in
the \midi{...} block (which ended up in Track 0) and another in the
beginning of some stave (which ended up in the corresponding track),
I would get different tempi for different sequencers.

Anyway, I'm still curious to hear from a MIDI expert how tempo changes
in the middle of a piece should be specified in a MIDI file? Should they
also be inserted (only) in track 0?

   /Mats

Nigel Warner wrote:
>         Dear All,
>
>         After running a check I believe that the problems people
>         are having with MIDI and Tempo are because Lilypond does
>         not do "the right thing".
>
>         Picking apart the MIDI output for a simple file:
>
>         panfluteAA = \notes {
>         \time 3/4
>         r2 \times 2/3 { d'8 e' g' }  |
>         g'4 fis' g' |
>         a' a'2   ~ |   a'   g'8( e')
>         }
>         \score {
>         \context Voice \panfluteAA
>         \paper { }
>         \midi{  }
>         }
>
>
> MFile 1 2 384
> MTrk
> 0 Meta Text "Creator: GNU LilyPond 2.0.1            "
> 0 Meta Text "Generated automatically by: GNU LilyPond 2.0.1            "
> 0 Meta Text "at Thu Oct 16 18:16:28 2003                                 "
> 0 Meta Text "from musical definition:
> /home/nigel/LilySource/TempoCheck.ly:9:25"
>
> 0 Meta SeqName "Track 0"
> 0 Meta TrkEnd
> TrkEnd
> MTrk
> 0 Meta TrkName ""
> 0 Tempo 1000000
> 0 TimeSig 3/4 18 8
> 768 On ch=1 n=62 v=127
> 896 Off ch=1 n=62 v=64
> 896 On ch=1 n=64 v=127
> 1024 Off ch=1 n=64 v=64
> 1024 On ch=1 n=67 v=127
> 1152 Off ch=1 n=67 v=64
> 1152 On ch=1 n=67 v=127
> 1536 Off ch=1 n=67 v=64
> 1536 On ch=1 n=66 v=127
> 1920 Off ch=1 n=66 v=64
> 1920 On ch=1 n=67 v=127
> 2304 Off ch=1 n=67 v=64
> 2304 On ch=1 n=69 v=127
> 2688 Off ch=1 n=69 v=64
> 2688 On ch=1 n=69 v=127
> 4224 Off ch=1 n=69 v=64
> 4224 On ch=1 n=67 v=127
> 4416 Off ch=1 n=67 v=64
> 4416 On ch=1 n=64 v=127
> 4608 Off ch=1 n=64 v=64
> 4608 Meta TrkEnd
> TrkEnd
>
>         This is not good MIDI. In a format 1 file, a file containing multiple
> tracks, Tempo changes should only appear in the Conductor track, track 0,
> which should only contain System Common messages. Quicktime, and other
> MIDI file players, are within their rights to ignore tempo changes, key
> signatures and time signatures which appear in tracks other than 0 which
> should only contain Channel Mode messages and Meta Events.
>
>         The reason I know this is because I have experimented with various
> combinations of data and MIDI reading software and have come to the
> conclusion that the only safe way is to ensure that the constraints
> as above are obeyed. The results of feeding a disobedient file into
> Sibelius, Finale and others are widely inconsistent and appear to depend
> on whim.
>
>         I would consider this to be a buglet.
>
>         Regards,
>
>         Nigel.
>
>
>
>
>
> _______________________________________________
> Lilypond-user mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/lilypond-user

--
=============================================
        Mats Bengtsson
        Signal Processing
        Signals, Sensors and Systems
        Royal Institute of Technology
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
        Fax:   (+46) 8 790 7260
        Email: address@hidden
        WWW: http://www.s3.kth.se/~mabe
=============================================