topic Re: piano in LabVIEW

piano

Cory_K — Thu, 30 Apr 2009 17:08:25 GMT

I am working on something just for fun.

Assuming you have a text file to start with (easier said than done),

that is formatted in the following manner:

Note Time held

.... etc

If I modified one of these programs, I would like to accomplish the following.

Read the text file.

Automatically play the song from the file.

But show which keys are being pressed while the piano is playing, so it could act as a tutorial.

I think the easiest way to do this would be to assign values to each key:

0 - 87 (including black and white keys)

Then I would read the file, which would say:
Note (0-87) Time held (ms)

Would I need to find a .wav file of each note on a piano?

Then put a 'play sound file' in a loop. But how would I specify how long the note held for?

I figure I could show which key is being pressed by changing the color of the control via property node or something.

Any advice while I'm coming up with something?

Re: piano

Cory_K — Thu, 30 Apr 2009 17:27:25 GMT

Instead of a .wav file that plays each note,

since each note already has an absolute pitch

I could use the 'beep.vi' function. I could convert pitch to frequency,

then input frequency and duration.

Re: piano

JÞB — Thu, 30 Apr 2009 17:48:55 GMT

Cory,

That sounds like a fun project!

I have a couple additional thoughts that you might consider so that a true tutorial can be realized.

you may need class.fingers method.down(key, duration, force) method.slide(array of keys, array of increments, force) allow 5 for Zichy composition, 20 for a duet

You might consider class.pianotype(grand, upright, electric, ect...) have fun! detune a few keys on a bad piano!

Incorporate footwork

Right pedal - The loud one. Also known as the "forte" or sustain pedal, it prevents dampers from descending on the piano strings, resulting in a rich, sustained chord peal.
Left pedal - The soft one or "una corda." A single piano note is normally created from two or three piano strings tuned in unison. This pedal shifts the hammer so that it hits only one or two strings, resulting in a more muted sound. Hence, "una corda" or "one string."
Middle pedal - The "sostenuto." This pedal selectively sustains notes, so that certain notes can ring out while others fade normally. It is usually found only on grand pianos.

your file then will contain a list of methods, start times and params for each finger and the foot.
You could show force as color for the display

Re: piano

Cory_K — Thu, 30 Apr 2009 17:50:59 GMT

Jeff,

Those all sound like great ideas. Thanks for the input.

The project is actually coming along pretty well.

Re: piano

JÞB — Thu, 30 Apr 2009 17:58:43 GMT

I'd love to see it when its complete! and your quite welcome.

Re: piano

falkpl — Thu, 30 Apr 2009 18:43:23 GMT

You could get fancy, and instead of using beep, you could create waveforms on the fly and feed it to a stream (buffer for audio output). The waveforms would be made from the note frequency and various harmonics with defined decays. There is probably some doccumentation of piano waveforms somewhere.

Re: piano

MattBradley — Thu, 30 Apr 2009 21:53:26 GMT

What about double notes (when you hit two notes at the same time). Come to think of it, you have two hands on the piano...

Re: piano

JÞB — Thu, 30 Apr 2009 22:02:49 GMT

http://en.wikibooks.org/wiki/File:Piano_waveform_reconstructed.svg,,, <<< that's a":" "P" (how to unsmiley?)

http://www.sharewareconnection.com/pianos.htm

And thats a 5min search

Message Edited by Jeff Bohrer on 04-30-2009 05:02 PM

Re: piano

JÞB — Thu, 30 Apr 2009 22:00:56 GMT

You are right-

Class fingers needs an owning class hands to control the max span between fingers.

Or, depend on the composer handleing that for you (and allow yourself to compose some quite unusual projects )

Re: piano

Cory_K — Fri, 01 May 2009 03:08:51 GMT

I have already thought of how I am going to implement single notes.

Chords will take some thinking, but I'll see what I can come up with.

Re: piano

Cory_K — Fri, 01 May 2009 16:05:40 GMT

falkpl wrote:
You could get fancy, and instead of using beep, you could create waveforms on the fly and feed it to a stream (buffer for audio output). The waveforms would be made from the note frequency and various harmonics with defined decays. There is probably some doccumentation of piano waveforms somewhere.

How would I change the sound from a beep, to sound more like a piano? Could you please explain further?

Re: piano

falkpl — Fri, 01 May 2009 16:41:11 GMT

beep is single tome (frequency) true sound form instruments are the sum of numerous harminics on the note and different decays. I was never a good musician, but each instrument will be have unique characteristics on the harmonics and decays, this is why all instruments sound different and not like a synthetic pure tone. using this approach to making each note, you can mix multiple notes into the same waveform for cords and even modulate the overall waveform and decay the amplitude so that note durations fade out after the note is played. This can get very complex, but is probably what electrical pianos are doing.

Re: piano

Cory_K — Fri, 01 May 2009 17:22:09 GMT

I've just about finished up with Keyboard.VI Version 1.0

The last thing that is holding me up is actually getting the files.

The easiest way to get music (besides .mp3) to work with is by downloading 'midi' files.

Somehow, I would need to convert the midi file into something I can actually use.
I would prefer if it was a text file or something easier to work with.

Any ideas?

Re: piano

Cory_K — Mon, 11 May 2009 17:05:31 GMT

OK, the piano part of the VI seems to be working great, provided I use a txt file as I described earlier.

The most common form of music I can find (that is easily compatible with a computer) is a 'MIDI' file.

Here is a detailed explination of how said file is formatted.

If you scroll to the very bottom of the page, it shows the Event Commands.
I'm thinking I could use 'Match Pattern' to find 'note on' and 'note off' events.
If I read the binary as strings, I can match:

1000****

1001****

for off and on respectively.

I'm assuming 'velocity' is the length of the note.

Does anyone have any advice on a better way to read the note and time?

These files contain MUCH more information about the song than I am looking for, but parsing out the file should enable me to extract only the pieces I am looking for.

another question I had was:
The notes they list are 0-127.

A piano only has 88 keys.
How would I account for the difference in number of notes? Or does a piano not contain all of the listed octaves?

Re: piano

ROtake — Mon, 11 May 2009 17:18:12 GMT

Hi Cory

This application is very suitable through MIDI protocol. Everything is already defined and implemented. You just need to find a way to interface LabVIEW with MIDI implementation already in use in most of computer sound cards.

Ricardo

Re: piano

Cory_K — Mon, 11 May 2009 17:30:13 GMT

I'm having a hard time opening a MIDI file in LabVIEW.

What exactly is it? A binary file?

I've tried both 'read text file' and 'read binary file', but get the following error:

And heres what the output looks like:

Message Edited by Cory K on 05-11-2009 12:30 PM

Re: piano

Cory_K — Mon, 11 May 2009 17:33:57 GMT

ROtake wrote:

Hi Cory
This application is very suitable through MIDI protocol. Everything is already defined and implemented. You just need to find a way to interface LabVIEW with MIDI implementation already in use in most of computer sound cards.
Ricardo

Hi Ricardo,
Playing the file is more of a secondary goal for this VI.

The primary reason I am creating this VI is to show the keys being pressed on the piano as it is played in real-time.

Once I figure that out, I will worry about playing the file.

Re: piano

nathand — Mon, 11 May 2009 17:54:28 GMT

Cory K wrote:
I'm having a hard time opening a MIDI file in LabVIEW.
What exactly is it? A binary file?

I've tried both 'read text file' and 'read binary file', but get the following error:

And heres what the output looks like:

I'm pretty sure that error is expected - it's telling you that it successfully read to the end of the file, in the same way that it would if you had specified some very large number of bytes to read (which is essentially what you've done by leaving the length input unwired). The file appears to be a binary file. The difference between binary and text files is handling of end-of-line and maybe some other special characters which can be translated when dealing with text but should be left untouched when treated as binary data. I haven't looked at the MIDI spec at all but my guess is that you'll want to create one or more clusters representing the MIDI data in a usable form, then break up the binary data you read from the file into appropriately sized chunks and typecast them to your clusters.

Re: piano

Cory_K — Mon, 11 May 2009 17:59:33 GMT

I don't have much experience working with Binary.

How am I supposed to handle those characters, like the squares?
Is there a way to convert binary to ascii? Then I could figure out what I'm dealing with.

Re: piano

johnsold — Mon, 11 May 2009 18:19:52 GMT

Cory,

All the bytes in both displays have already been converted to ASCII. Perhaps you want a display in hex. Or maybe you want to display the non-alphanumeric characters in hex?

Just change the string indicator display format to Hex or to '\' Codes Display. Neither of these changes the underlying data, only how it looks in the indicator.

Lynn