25 Jun
2010
25 Jun
'10
12:55 p.m.
Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
1) Notes of zero duration?
Are these legal MIDI? Do I send a note-on with simultaneous note-off?
Or should they simply be ignored?
2) note x ending simultaneously with note y beginning
For example, a sequence of eighth notes, each an eighth in duration.
As far as processing of these events goes, which should be processed first?
Cheers,
James.
25 Jun
25 Jun
1:36 p.m.
On Fri, 2010-06-25 at 11:55 +0100, James Morris wrote:
Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
Midi is serial, first come first served.
1) Notes of zero duration?
Are at least one millisecond.
2) note x ending simultaneously with note y beginning
Note x will end either one millisecond before or after y beginning.
/j
--
jedes mal wenn du eine quintparallele verwendest
tötet bach ein kätzchen.
http://www.youtube.com/watch?v=43RdmmNaGfQ
1:51 p.m.
On 25 June 2010 12:35, Jens M Andreasen <jens.andreasen(a)comhem.se> wrote:
On Fri, 2010-06-25 at 11:55 +0100, James Morris wrote:
Sorry, should have mentioned this is with regard to the internals of sequencing.
I can't see in Seq24 for example a way to make a zero length note.
Where do you get the one millisecond from?
Does this imply that a note-off should always happen one millisecond early?
Cheers,
James.
Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
Midi is serial, first come first served.
1) Notes of zero duration?
Are at least one millisecond.
2) note x ending simultaneously with note y beginning
Note x will end either one millisecond before or after y beginning.
/j 
2 p.m.
On Fri, 2010-06-25 at 12:51 +0100, James Morris wrote:
Does this imply that a note-off should always happen
one millisecond early?
I've got no knowledge how to program for Linux, but regarding to those
oldish sequencers. No, a note-off should always is send at the correct
time.
--
http://www.youtube.com/watch?v=vclX__c51T8&feature=PlayList&p=CFAAA…
http://www.youtube.com/watch?v=ryOzXQkFO5Q&feature=PlayList&p=CFAAA…
http://www.youtube.com/watch?v=PukuQPUKfyU&feature=PlayList&p=CFAAA…
2:13 p.m.
On 25 June 2010 12:51, James Morris <james(a)jwm-art.net> wrote:
On 25 June 2010 12:35, Jens M Andreasen
<jens.andreasen(a)comhem.se> wrote:
Not to worry. I think my code is flawed, needs to redesign
somewhere... with bin-packing, you have one thing to take out at the
same time as one thing to put in, it's obvious to do the taking-out
before the putting-in! but there's problems in my design making it
difficult to perform operations in that order.
Cheers,
James.
On Fri, 2010-06-25 at 11:55 +0100, James Morris wrote:
Sorry, should have mentioned this is with regard to the internals of sequencing.
I can't see in Seq24 for example a way to make a zero length note.
Where do you get the one millisecond from?
Does this imply that a note-off should always happen one millisecond early?
Cheers,
James. Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
Midi is serial, first come first served.
1) Notes of zero duration?
Are at least one millisecond.
2) note x ending simultaneously with note y beginning
Note x will end either one millisecond before or after y beginning.
/j 
3:46 p.m.
On Friday, June 25, 2010, James Morris wrote:
On 25 June 2010 12:35, Jens M Andreasen
<jens.andreasen(a)comhem.se> wrote:
MIDI is an asynchronous serial interface. The baud rate is 31.25 kBd +/-1%.
There is 1 start bit, 8 data bits, and 1 stop bit. The period is about 320
microseconds per serial byte. Note on/off messages are 2 or 3 bytes in
length, depending on running status being used or not.
On Fri, 2010-06-25 at 11:55 +0100, James Morris
wrote:
Sorry, should have mentioned this is with regard to the internals of
sequencing. I can't see in Seq24 for example a way to make a zero length
note.
Where do you get the one millisecond from? Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
Midi is serial, first come first served.
1) Notes of zero duration?
Are at least one millisecond.
2) note x ending simultaneously with note y
beginning
Note x will end either one millisecond before or after y beginning.
/j Does this imply that a note-off should always happen
one millisecond early?
There are instruments that always ignore note off messages, for instance many
percussion instruments. In this case, you can safely omit note off messages.
Regards,
Pedro
2:29 p.m.
On Fri, Jun 25, 2010 at 6:55 AM, James Morris <james(a)jwm-art.net> wrote:
Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
just remember that in "real" MIDI, nothing can be simultaneous. its a
serial protocol without timestamps. with traditional serial MIDI, the
time interval between bits and bytes is also fixed, creating a fixed
minimal interval between any two note on/off messages.
2:38 p.m.
On Fri, 2010-06-25 at 08:29 -0400, Paul Davis wrote:
On Fri, Jun 25, 2010 at 6:55 AM, James Morris
<james(a)jwm-art.net> wrote:
In addition, the UART gives information about being ready to send. It's
not fixed to e.g. 1ms. There's a register giving this information.
Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
just remember that in "real" MIDI, nothing can be simultaneous. its a
serial protocol without timestamps. with traditional serial MIDI, the
time interval between bits and bytes is also fixed, creating a fixed
minimal interval between any two note on/off messages.
3:36 p.m.
On Fri, 2010-06-25 at 14:38 +0200, Ralf Mardorf wrote:
On Fri, 2010-06-25 at 08:29 -0400, Paul Davis wrote:
Note, there's nothing fixed, the limitation is just for the max Baud
MIDI is able to do. Regarding to the term 'fixed' UART is for 'Universal
Asynchronous Receiver Transmitter', the important word is
'Asynchronous'. We are talking about microseconds, taking care about the
CTS and RTS registers. Regarding to all that MIDI jitter, I wonder if
ALSA seq, might has to do with it. I don't know, perhaps there are
issues for USB specifications, but maybe there's something bad for this
'timestamp' routs.
*?*
I programmed on Assembler directly using the UART and there never was
jitter.
Could this be a reason for MIDI jitter using Linux or has it nothing to
do with it? Because, at the other hand there's no jitter internal the
studio in the box.
*?*
Ralf
On Fri, Jun 25, 2010 at 6:55 AM, James Morris
<james(a)jwm-art.net> wrote:
In addition, the UART gives information about being ready to send. It's
not fixed to e.g. 1ms. There's a register giving this information. Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
just remember that in "real" MIDI, nothing can be simultaneous. its a
serial protocol without timestamps. with traditional serial MIDI, the
time interval between bits and bytes is also fixed, creating a fixed
minimal interval between any two note on/off messages.
3:51 p.m.
On Fri, 2010-06-25 at 15:36 +0200, Ralf Mardorf wrote:
On Fri, 2010-06-25 at 14:38 +0200, Ralf Mardorf
wrote:
I can't remember, perhaps CTS and RTS are flags in one register and
maybe they have other acronyms ;), anyway, this is the important stuff.
Pedro Lopez-Cabanillas did post the technical specifications.
On Fri, 2010-06-25 at 08:29 -0400, Paul Davis
wrote:
Note, there's nothing fixed, the limitation is just for the max Baud
MIDI is able to do. Regarding to the term 'fixed' UART is for 'Universal
Asynchronous Receiver Transmitter', the important word is
'Asynchronous'. We are talking about microseconds, taking care about the
CTS and RTS registers. Regarding to all that MIDI jitter, I wonder if
ALSA seq, might has to do with it. I don't know, perhaps there are
issues for USB specifications, but maybe there's something bad for this
'timestamp' routs.
*?*
I programmed on Assembler directly using the UART and there never was
jitter.
Could this be a reason for MIDI jitter using Linux or has it nothing to
do with it? Because, at the other hand there's no jitter internal the
studio in the box.
*?*
Ralf On Fri, Jun 25, 2010 at 6:55 AM, James Morris
<james(a)jwm-art.net> wrote:
In addition, the UART gives information about being ready to send. It's
not fixed to e.g. 1ms. There's a register giving this information. Hi,
I keep getting surprised at some of the most basic problems I run
into... This time, processing order.
just remember that in "real" MIDI, nothing can be simultaneous. its a
serial protocol without timestamps. with traditional serial MIDI, the
time interval between bits and bytes is also fixed, creating a fixed
minimal interval between any two note on/off messages. 
3:29 p.m.
James Morris wrote:
1) Notes of zero duration?
Are these legal MIDI?
Yes. There are synthesizers that can play percussion sounds at their
natural length and ignore note-off messages, so, sometimes, note-off
timing isn't available.
Do I send a note-on with simultaneous note-off?
Yes. Some standards say that each note-on must have a corresponding
note-off.
2) note x ending simultaneously with note y beginning
For example, a sequence of eighth notes, each an eighth in duration.
As far as processing of these events goes, which should be processed first?
This depends. It is possible that a synthesizer plays these notes in
legato for certain instruments, but only if the note-on of the second
note is received before the note-off of the first note. And it's
possible that certain other notes are _not_ intended to be played legato.
Multiple messages with the same timestamp should never be reordered by
the sequencer.
Regards,
Clemens
7:07 p.m.
On Fri, Jun 25, 2010 at 9:29 AM, Clemens Ladisch <clemens(a)ladisch.de> wrote:
there are 3 pages (minimum) of discussion of this behaviour in the
MIDI spec. there are at least 4 options for how a receiver can behave.
James Morris wrote:
I have the full MIDI spec in front of me. It states very clearly that
a sender MUST always send a note off for every note on, regardless of
whether a receiver pays any attention to it.
1) Notes of zero duration?
Are these legal MIDI?
Yes. There are synthesizers that can play percussion sounds at their
natural length and ignore note-off messages, so, sometimes, note-off
timing isn't available.
Do I send a note-on with simultaneous note-off?
Yes. Some standards say that each note-on must have a corresponding
note-off. 2) note x ending simultaneously with note y
beginning
For example, a sequence of eighth notes, each an eighth in duration.
As far as processing of these events goes, which should be processed first?
This depends. It is possible that a synthesizer plays these notes in
legato for certain instruments, but only if the note-on of the second
note is received before the note-off of the first note. And it's
possible that certain other notes are _not_ intended to be played legato.
5065
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linux-audio-dev@lists.linuxaudio.org
11 comments
6 participants
participants (6)
-
Clemens Ladisch -
James Morris -
Jens M Andreasen -
Paul Davis -
Pedro Lopez-Cabanillas -
Ralf Mardorf