Music in Matlab

Finals and additional office hours

2005-12-07T12:27:00.000-08:00

There were several inquiries about the time of the final. According to
Tritonlink, it is Friday Dec. 9, 3 - 6 p.m.
https://tritonlink.ucsd.edu/portal/site/tritonlink-preview/menuitem.b4448692267a11256ec5e210514b01ca?storyID=18016

I will hold additional office hours tomorrow (Thu.) 2-4 pm.
My office location is Mandeville Center, Room B139

Shlomo

Additional office hours

2005-12-02T07:43:00.000-08:00

I will be available for meetings Tuesday 12-6, between 10am - 12, 1- 5pm at
my office (Mandeville Center, Room B139).

Scheduled meetings

2005-12-01T00:48:00.000-08:00

The reserved / open slots for tomorrow (Thu. 12-1) are:
12:30 Mehrdad
1:15
2:00 Kristine
2:45
3:30 Richie ?
4:15

No class on Wed 11-30 and extended office hours on Thu. 12-1

2005-11-28T12:07:00.000-08:00

Attention! For those who missed the last class meeting, note that there
will be no class on Wed 11-30.
I will hold extended office hours on Thu. 12-1 from 12:30 till 5:00.
Final exam (projects presentation and discussion) will be on Fri. 12-9.

If you would like to discuss your project on Thu., please bring it with you
or email me the presentation / code before the meeting.
Also, if you would like to reserve a specific time-slot, please email the
requested time.

Projects and other

2005-11-10T09:35:00.000-08:00

Here is a short explanation about the FM synthesis project that I promised:
- fm synthesis uses the principle of fm modulation to create sidebands around a carrier frequency. It is a very fast method to generate a complex
spectrum from only few oscillators. John Chowning developed this method into music synthesis, so that by a careful selection of the modulation
index and other parameters, one can emulate real instruments, from woodwinds to bells, to drums and etc.
The method is described in a paper that I've put in http://music.ucsd.edu/~sdubnov/Mu176/Projects/Chowning-FM.pdf Miditoolbox playsound.m is an implementation of one such instrument. The purpose of the project is to add other instruments, according to the
parameters that are described in the paper.

Other addenda:

- I've added a new mfile texturesyn.m in the LSEE folder in mfiles
directory. This is a demonstration of using LSEE to generate a long sound
from a random assembly of spectral clips drawn from analysis of a natural
sound (jungle). This is related to so called "granular synthesis" (but done in a "smart" way ;) or "audio texture synthesis".

- I've put midi and mp3 files for the Bach prelude in the Lab2 directory.

- If anyone has a good summary of yesterday's class on DFT, zero padding
and windowing effects, I would like to put a copy on the blog. Note that some of the material (basic DFT) appears in http://music.ucsd.edu/~sdubnov/Mu176/ClassTalks/172oldnotes.pdf
If preparing these notes requires extra work, I'm willing to take this instead of one of the exercises, or as an extra credit.

Faculty Mentor Program

2005-11-05T11:26:00.000-08:00

I have offered two of the projects for continuation through the faculty mentor program this Winter and Spring. I believe that this entitles the student taking it for some payment and a 199 credit. See http://ugresearch.ucsd.edu/default.asp for more details on Ghostklavier and Audio Spectral Design.

DFT review

2005-10-24T21:02:00.000-07:00

I put a scan of lecture notes on complex numbers and Discrete Fourier
Transform at http://music.ucsd.edu/~sdubnov/Mu176/ClassTalks/172oldnotes.pdf

Notes on Instantaneous Frequency and the Phase Vocoder

2005-10-17T23:56:00.000-07:00

Read a short (6 pages) summary of the Instantaneous Frequency and the Phase Vocoder at http://music.ucsd.edu/~sdubnov/Mu176/ClassTalks/ClassTalk2.pdf

We will discuss these notes in the next class.

Assignment II - makeup and addendum

2005-10-13T08:31:00.000-07:00

As a quick reminder, the frequency has to be integrated to get the phase.
The command for that in Matlab is cumsum.
For our next class correct / complete the chirp assignment. Design your
initial and final frequency so that it starts below Nyquist and goes over
it (if you want, it can continue rising beyond sampling frequency as well).
Describe what you hear. See this in specgram. Explain.
Note: in order to keep the aliasing effect in audible range, use Nyquist
around 2KHz.

Project Ideas

2005-10-12T09:10:00.000-07:00

1/f noise generator for Wav & MIDI (Voss-Gardner method)

Audio Texture synthesis (Lie et al. paper)

Multipitch detection (Tolonen paper)

Wav to midi (monophonic): create midi file from pitch detection.

Query by humming: use pitch contours and autocorrelatoin to find a tune by humming.

Specgram from midi: creat a spectrogram directly from midi file (without synthesis).

Midi expressive timing: do time warping of a midi file from wav of a real performance.

Midi expressive dynamics: change dynamics of a midi file according to wav.

Wav alignment: same as midi, but for two wav performances of same music.

Do a wavetable synthesis program using time domain resampling.

Do a wavetable synthesis using spectral domain pvoc.

Add instruments to fm synth (Chowning paper)

Native matlab midiread and midiwrite (including control parameters).

Midi filters: add / remove legato or staccatto in a midi file.

Chord finding: extend the key finding method to detect chords.

Polyphonic midi reduction: extract theme or theme and chords from polyphonic midi.

assignment II

2005-10-07T17:04:00.000-07:00

Here is a short follow up on what we started in class.

1. Create a matlab function that returns a sinusoid (a sound vector, i.e. a vector containing samples of the sinusoid). The inputs to the function should be sinusoid frequency, amplitude, duration and sampling frequency.
Analize it with specgram and look at the figure. Explain what you see. Write the results of the specgram command into a matrix. Look at the absolute values of the matrix. Which bins correspond to the sinusoidal frequency? Explain the results. (We did briefly that in class).

2. Modify the function in 1 so that it receives a vector of frequencies and amplitudes (you do not need duration now). The length of there vectors should be equal to the length of the output sound vector. The values of these vectors should be the instantaneous frequency and amplitude at that sample (moment in time). Test your function for a slowly sloping frequency (a slow chirp or glissando, i.e. frequency slowily increasing (or decreasing) in time). Play your result. Does it sound right? Plot it with specgram. What do you see. (Hint: make sure you calculate the phase correctly. We will talk about this in class).

Shlomo

mfiles

2005-10-05T21:26:00.000-07:00

The mfiles directory should have read permissions now. It contains the miditoolbox and mp3_toolbox.

Bit depth and specgram - assignment I

2005-09-29T10:48:00.000-07:00

Here is a short assingement, to work out the meaning of bit depth. Bring it to the next class 10/5.

1. Record a sound using your computer audio recording application. Set the Audio sample size to 8 bits. Do the same using 16 bits. Listen to both sounds. Read them into matlab. Explain where you hear the difference. Can you see this in the waveform plot? Explain.
(To record a sound from internal source, like your midi player, set your recording properties in the volume control-> recording, to SW sytn. To set the sample size, on Windows open sound recorder and go to file->properties and click on "convert now".)

A second short assingment will show how the spectrum of the same musical piece changes with an instument type.

2. use miditoolbox playsound (or nmat2snd directly) to synthesize a midi file with 'fm' or 'shepard' timbre. Do specgram analysis of the resulting sound. Use NFFT=1024 or more. Record the same midi file by using your computer audio card or another synth. (See previous assignemnt for instructions on how this is done). Compare the specgram of this recording to the previous one. Explain the differences.

Welcome

2005-09-29T10:43:00.000-07:00

This is a blog for Music 176 seminar, Fall 2005, Department of Music, UCSD, led by Shlomo Dubnov. The purpose of the blog is to help exchange information, questions, suggestions and ideas about the class material and student projects. For course webpage see http://music.ucsd.edu/~sdubnov/Mu176