The MIDI Forum

Hello,

I don't want to get too bogged down regarding js, however...

The first byte is NOT the channel. The first byte will probably comprise two 4 bit numbers, the first part is the command, i.e. 9 for Note On, the second 4 bits will be the channel. dealing with this byte as 192 to 207 will be confusing. Surely? as Decimal even worse. So &H90 is Note On on channel 0, I suspect that the data you're seeing has this data already translated, so you don't see the (for example) 192 any more, but a reference to Note On, and somewhere a channel? In any case, 192 is not &H9x, but &HC0 - Program Change. So the decimal numbers you show are prob all correct, just not how they'd normally show.

In any case, the translation would prob not show the command number, just a channel. Somewhere?

Geoff

https://tonejs.github.io/Midi/

Well just click the github link, and you can see what it parse out.
I can't see any channel information either for notes or instruments "just on / off".

But you are correct he has already translated note off into duration.

Jonas

Geoff 192-207 is the first byte, and denotes which channel "a change of instrument" take place on.
.
Javascript made it very easy to handle midi, someone was smart, all messages or message chain either consist off two or three byte values.
Instrument change is a two byte value. Where the first byte if between 192-207 denotes which channel the change occure on.

So the **first byte** do denote channel.

CC 176-191
instrument 192-207
Note On 144-159
Note Off 128-143

The use of byte values made it very easy program midi in javascript.

Second byte is CC type, Note value or program.

Third byte "if there is one" is the range, so they gained alot by using bytes. And doing it using stringified decimals, compared to hex, of course one use decimals.
Because then you can actually read the code.

Best regards Jonas Thörnvall

Of course you may see a deeper meaning within the bit to byte structure "first four bits message type last four midichannel" then me, but it is however true that for the ranges within first byte above they do denote the midichannel weither it was intended or not.

And you have to admit Geoff it is much easier to work with bytes then bits, and i can't see why anyone would prefer bits,hex bytes to decimal byte values.

CC 176-191
instrument change 192-207
Note On 144-159
Note Off 128-143
Pitchbend 224-239
Polyphonic key pressure 160-175
Channel pressure 208-223

I think i got all the all the supported midichannel messages there, and their range within first byte?

Looking at it again i can see the midi channel probably hides behind the label midi, but i do not get the range, how does he parse out the values?

https://tonejs.github.io/Midi/

"I guess it is a bit saving mechanism", so how does he parse out those values ranging 40-80 "estimation" out of the byte?

You may ant to ave a look at https://github.com/jazz-soft/JZZ and https://github.com/jazz-soft/JZZ-midi-SMF

I now realise of course it is HEX values for midchannel he use "i am just stuck with bytes in my head". But i don't get it the values is all over the place?
36 - 80
Look for the label midi on the notes i think that must be the channels, can some smart fellow tell me howto decode it?
I just do not get it his range much bigger then number of midichannels, so how to decode it "how did he encode it"?
Help please, it is detective work to figure out how he encoded it, because even if hex it really does not make sense?

Could he read out the bits wrong way back to front, but i still can't get it working maybe also multiply?

https://tonejs.github.io/Midi/

Yeah i think so Geoff it strange i just scrolled it thru in the HTML textarea but i had a rahter big midi file Queen Bohemina Rhapsody with dozens of instrument changes but i did not manage to catch the midi channel messages you speak of. Have to go back and do it again and paste into editor like you and search for channel information. Well this is what comes with being sloppy i guess.

Thanks Geoff

Jonas,

Hm, maybe not a good idea to be using a large file for your testing - the conversion is very verbose, and leave a massive pile of data to pore through.

Nothing to do with being 'sloppy', more like looking for a needle in a haystack?

On the basis of what you'd written before, I guess I'd instinctively wondered if the problem was that the channel marker was seperated - as it seems to be. I've spent a lot of time over a lot of years looking inside midi files, and messing with software (incl my own progs) to 'do things' with such files, incl play them. Even though I was scrolling through the initial file very quickly, I spotted something that made me stop and go back to where it said 'channel': 0 and I thought - Aha!

I don't want to get involved in programming with js, I'm dealing with enough other languages already. So best of luck with your project.

Geoff

Jonas,

Just a hint in case it helps.

You will ALWAYS need to split the command byte, into the command and the channel. It will NEVER be any use keeping this as a single value.

There are different ways to do this, I've seem variants where AND/OR is used to mask off some of the bits.

The way I prefer is somewhat clearer. Ensure that the byte value is an INT (integer) and divide by 16. This will give you the integer Command, i.e. 9 for Note On, regardless of channel. Then put this into another INT variable, and multiply by 16, and minus the result from the original byte value. This will give you the channel number, on its own. NB all the variables for this MUST be integers, you don't want any decimal places.

Regarding something you wrote earlier, if you check the official spec for midi files, there should be a piece of sample code for the read/translation of the timing bytes into something more useful, and it should not be a problem to convert the code into js. I have a working version in 'C' if that would be more help. The published version is in 'C' in the doc I have, but I think I changed it slightly.

Geoff

Hello Geoff!

Just read your reply, working with javascript i can't see the necessity, but then again my sequenser is not midicompatible although it will import midifiles to play.
I can show you what is sent out to a port using javascript, and this works fine for every type of event i can find even bankchanges. You can see below it is silly simple dealing with it.
Only thing to realise that some messages 2 bytes instead of three, "program change, note off".
I just look at the range to determine the type of event, so do not need to split the byte.

Thanks again for the help Geoof, i think to Cristmas i will have a somewhat functional midisequenser load save edit and so on, i probably should have a timeview and a FPS view instead of just a barview. But the barview did seem most easy to start with.

Looking at the code below i do realise now i split, but i still think a decimal range is easier handled then pairing two 4-bit hexvalues.


Thanks again for the help Geoff!

function sendProgram() {
//Set program on the track
programNbr = document.getElementById("prog_sel".value;
//Set channel
midiCh = 192 + trackMidiCh-1;
//Build message for midi synth
settingChange = [midiCh, programNbr];
outportarr[outportindex].send(settingChange);
}

function setVol(){
CCchan=176+trackMidiCh-1;
CCtype=7;
CCvol=document.getElementById("volID".value;
settingChange=[CCchan,CCtype,CCvol];
outportarr[outportindex].send(settingChange);
}

function setPan(){
CCchan=176+trackMidiCh-1;
CCtype=10;
CCpan=document.getElementById("panID".value;
settingChange=[CCchan,CCtype,CCpan];
outportarr[outportindex].send(settingChange);
}

function setRev(){
CCchan=176+trackMidiCh-1;
CCtype=91;
CCrev=document.getElementById("revID".value;
settingChange=[CCchan,CCtype,CCrev];
outportarr[outportindex].send(settingChange);
}

function setChor(){
CCchan=176+trackMidiCh-1;
CCtype=93;
CCchor=document.getElementById("chorID".value;
settingChange=[CCchan,CCtype,CCchor];
outportarr[outportindex].send(settingChange);
}

function setMod(){
CCchan=176+trackMidiCh-1;
CCtype=1;
CCmod=document.getElementById("modID".value;
settingChange=[CCchan,CCtype,CCmod];
outportarr[outportindex].send(settingChange);
}

function setHold(){
CCchan=176+trackMidiCh-1;
CCtype=64;
CChold=document.getElementById("holdID".value;
settingChange=[CCchan,CCtype,CChold];
outportarr[outportindex].send(settingChange);
}

https://midisequenser.000webhostapp.com/

Although i am not sure i hope you wow for my halfbaked attempt to a sequenser, full of bugs.
But to Christmas i hope most of them gone and editing, load save and midi file import fully functional.