Re: MIDI time signature

[David Kastrup]

Dan Eble <dan@faithful.be> writes:

> On Jun 6, 2021, at 17:32, David Kastrup <dak@gnu.org> wrote:
>> 
>> I'd argue that if we have
>> 
>> \tempo 60
>> \time 6/8
>> 
>> then we should likely interpret this (regarding the MIDI playing speed)
>> as
>> 
>> \tempo 60 = 4.
>> \time 6/8
>
> Is "\tempo 60" without a note duration a typo or is it a proposal for new 
> syntax?  It doesn't currently work for me here:
>
>     \score {
>       \new Staff {
>         \tempo 60
>         \time 6/8
>         c'4. 4.
>       }
>       
>       \layout {}
>       \midi {}
>     }

Uh.

tempo_event:
        TEMPO steno_duration '=' tempo_range    {
                $$ = MAKE_SYNTAX (tempo, @$, SCM_EOL, $2, $4);
        }
        | TEMPO text steno_duration '=' tempo_range     {
                $$ = MAKE_SYNTAX (tempo, @$, $2, $3, $5);
        }
        | TEMPO text {
                $$ = MAKE_SYNTAX (tempo, @$, $2);
        } %prec ':'
        ;

Shiver me timbers.  You are right.  And I certainly won't argue for
introducing more ambiguous notation here, so consider that part of my
musings dead.

> In my scores that use 6/8, I've already specified the beat as "4.", e.g.
>
>   \time 6/8
>   \tempo 4. = 64
>
> so I don't understand why it would be important to have an alternative that 
> is interpreted the same way.

It isn't interpreted the same way.  If you transfer that file to a MIDI
arranger, it contains time signature information that will result in a
wrong display of bpm and a wrong display of metronomic counting.

If you _play_ that file on your computer and
record/transfer/expand/whatever the raw MIDI, there is no time signature
information contained in the raw MIDI or the sound.  It's purely
something living in the MIDI files.  But programs, sequencers, DAWs and
arrangers actually working from the file may very well take it into
account.

A \tempo statement (obviously) will affect even the generated raw MIDI
stream.  But \time just lives in MIDI files before they are converted
into a raw MIDI stream or other audible representation.  It doesn't
survive into the sound.  And there are still reasons to get it right.

-- 
David Kastrup