| Author |
Help on Polyphonics |
Bluejackers
Joined: Nov 11, 2003
Posts: 92
From: Scotland
PM, WWW
|
Can anyone help.
I am building a free ringtone web site and trying to determine the number of channels in a midi file. The question is, what is the capability of a phone when it comes to playing a Midi - if the phone can play 4 channels, does that mean that it can play ANY 4 channels of the 128 midi instruments concurrently or is it restricted to just 4 instruments?
For example, if I have a MIDI that uses say 12 instruments but at no one time does it play more than 4 at any one point in time, will that play correctly on a phone with a 4 channel capability?
Many thanks if someone can help
Steve
| |
|
Cycovision
Joined: Nov 30, 2003
Posts: > 500
From: England
PM, WWW
|
The chances are that most four channel midi phones would play only the first four channels.
Example:
Someone writes and exports a six channel tone with instruments assigned as follows -
channel 1 = bass drum
channel 2 = snare drum
channel 3 = closed high-hat + open high-hat (never both play at the same time, and so can share one channel)
channel 4 = piano
channel 5 = trumpet
channel 6 = flute
The four channel phone would only play the first four channels which in this case would be the bass drum, snare drum, high-hats and piano. It would ignore the trumpet and flute even if they don't play at the same time as the other instruments. For this to happen, the midi would have to be constructed thus:
channel 1 = bass drum
channel 2 = snare drum
channel 3 = closed high-hat + open high-hat
channel 4 = piano, trumpet and flute
Obviously, the piano trumpet and flute instruments can not play at the same time.
Also, I've heard that some nokia phones won't play a midi file at all unless it's been processed by their own midi 'ringtone converter' software, presumably to make sure that the above problem does not occur. Not sure about other brands, could well be the same.
You might like to download 'modplug tracker' from http://www.modplug.com
This will allow you to load in your midi files, increase or decrease the number of channels, edit the channels and export the files using instruments of your choice.
_________________
'He who laughs last, laughs longest. Or didn't get the joke...'
[ This Message was edited by: Cycovision on 2004-03-02 12:25 ] |
Bluejackers
Joined: Nov 11, 2003
Posts: 92
From: Scotland
PM, WWW
|
That's awesome - thanks for the advice
I'll take a look at the site you suggest. I'll write a piece of code to read the MIDI file and determine the number of instruments which is a start - Im not sure that I can edit each of them in turn to the format you suggest (is that what they refer to as SP-MIDI?) as there are over 25,000 of them - LOL
I might have to add links to various software downloads so that the visitor can convert their favorites themselves depending upon their phone model.
Thanks again
Steve
|
Cycovision
Joined: Nov 30, 2003
Posts: > 500
From: England
PM, WWW
|
Yes, SP-MIDI stands for Scaleable Polyphonic midi, it's basically an extra set of instructions that are included with the midi file itself that tells different midi devices which instruments (or channels I suppose) to play and which to ignore, depending on the capabilities of the device. These instructions are set by the composer of the midi file.
There's a good page about SP-MIDI here, along with links to various SP-MIDI editors. One of them includes source code that might help you to code your mass-editing app 
http://www.midi.org/about-midi/abtspmidi.shtml
|
Bluejackers
Joined: Nov 11, 2003
Posts: 92
From: Scotland
PM, WWW
|
This gets more interesting 
Have analysed the MIDI 0 files we find that for example the MIDI is setup using 6 channels - 0,1,2,5,7,10
If we have a 4 channel polyphonic phone such as the Nokia 7210, does it only recognise channels 0,1,2,3 or will it recognise 0,1,2,5 and play those, ignoring 7 and 10 ?
When we rewrite the MIDI I need to know if there is any benefit in rewriting channel 5 as channel 3 in the above example.
Again, my thanks
Steve
| |
|
Access the forum with a mobile phone via esato.mobi
|
Posted: 2004-03-02 09:47
