Up: Multimedia Module No: CM3106

Multimedia (CM3106) PDF Tutorial Notes/Lab Class Exercises

PDF Tutorial and Lab Class Materials

Tutorial/Lab Class 1 (Week 2)
- CM3106_Lab_1_1_and_1_2_DSP_Filters.mlx (MATLAB Live Script)
- CM3106_Lab_1_3_Fourier_Transform.mlx (MATLAB Live Script)
- Tutorial 1 Notes: Basic DSP, Filters and Fourier Transform (PDF)
- Lab 1 (Week 2): Basic DSP, Filters and Fourier Transform (PDF)
- Tutorial and Lab MATLAB Code and support Material
  - Zip file of all MATLAB CODE etc
  - Individual Files
    - Lab Sheet Basic Digital Signal Processing Question 1: Basic Waveform creation and display
      - mysin.m, Basic Sin Wave Creation.
      - synth.m, Basic Waveform Creation.
      - sinampdemo.m, Example Sin Wave Creation: change amplitude
      - sinfreqdemo.m, Example Sin Wave Creation: change frequency
      - sinphasedemo.m, Example Sin Wave Creation: change phase
    - Lab Sheet Basic Digital Signal Processing Question 2: IIR/FIR Filters
      - IIRdemo.m (Simple Filter bank creation Eg.)
      - subtract_synth.m (Subtractive Synthesis Eg.)
    - Lab Sheet Fourier Transform Question 1: Phase Shifting in Fourier Transform
      - fft_phase_eg.m
      - See also Phasor Phase Shift Example,phasor_rotate_eg.m, (MATLAB Symbolic Toolbox) from Tutorial.
      - See also CM2202 Complex Number Notes for a recap on Phasors etc. (if required).
    - Lab Sheet Fourier Transform Question 2: fftshift(), shifting in the Fourier Transform
      - Example use of FFTshift, see Tutorial notes.
    - Lab Sheet Fourier Transform Question 3: Fourier Spectra
      - fourierspectraeg.m
    - Lab Sheet Fourier Transform Questions 4-7: Fourier Low Pass filtering: Audio
      - lowpass.m Example program ( Image Filtering).
  - Lab Sheet Fourier Transform Questions 8: Spectrogram
    - Daphex.m Example program
    - im2sound.m called by Daphex.m
    - Aphex_Spectrogram.m Shows orignal Apahex Twin Spectrogram image (uses FormulaSnippet.wav)
      Media Used:

Tutorial/Lab Class 2 (Week 3)

CM3106_Lab_1_3_Fourier_Transform.mlx (MATLAB Live Script)
Tutorial 2 Notes: Sample-based Synthesis, Coursework, Nyquist’s Sampling Theorem, Time-Frequency Analysis (PDF)
Lab 2 (Week 3): Nyquist’s Sampling Theorem, Time-Frequency Analysis (PDF)
Zip of all MATLAB Code.
Tutorial and Lab MATLAB Code and support Material
- Lab Sheet MATLAB Basic Digital Signal Processing Question 1: Nyquist’s Sampling Theorem
  - nyquist_aliasdemo.m
  - nyquist_aliasaudiodemo.m
- Lab Sheet MATLAB Time-Frequency Analysis Question 1: Short-time Fourier Transform
  - stft.m
  - istft.m
- Lab Sheet MATLAB Time-Frequency Analysis Question 2: Phase Vocoder (all file in Zip)
  - pvoc_speed.m
  - pvoc_pitch.m
  - pvsample.m
  - stft.m
  - istft.m
  - stft_spectra_edit.m (Simple Example of Editing Spectra with the Phase Vocoder)
  - stft_spectra_edit_eg.m, similar to stft_spectra_edit.m, example of hum removal from this file, handel_hum.wav

Tutorial/Lab Class 3 (Week 4)

Lab 3 (Week 4):Digital Audio Synthesis (Part 1) (PDF)
- Zip of all MATLAB Digital Audio Synthesis Example Code.
- Question 1 Subtractive Synthesis:
  - subtract_synth.m
  - synth.m (Use to create Waveforms)
- Question 4 Additive Synthesis:
  - additive_synth.m
  - synth.m (Use to create Waveforms)
- Questions 6+7 FM Synthesis:
  - fm_eg.m
  - synth.m (May also be used to create FM Waveforms)

Tutorial/Lab Class 4 (Week 5)

Lab 4 (Week 5):Digital Audio Synthesis (Part 2), Digital Audio Effects (PDF)
- Zip of all MATLAB Digital Audio Synthesis Example Code.
- Zip of all MATLAB Digital Audio Effects Example Code.
- Digital Audio Synthesis Question 2: Wavetable Synthesis:
  - wavetable_synth.m
- Digital Audio Synthesis Question 3: Granular Synthesis:
  - Zip of all MATLAB Granular Synthesis Example Code.
- Digital Audio Synthesis Question 4: Physical Modelling Synthesis:
  - Zip of all MATLAB Karplus Strong Example Code.
- Digital Audio Effects Question 1: Equalisation
  - shelving_eg.m.
  - shelving.m.
- Digital Audio Effects Question 2+3: Phaser/Wah-Wah
  - wah_wah.m.
- Digital Audio Effects Question 4+5: Chorus/Flanger + Resonator/Slapback/Echo
  - flanger.m.
- Digital Audio Effects Questions 6 + 7: Ring Modulation
  - ring_mod.m
- Digital Audio Effects Question 8: Amplitude Modulation
  - ring_mod.m
  - tremolo1.m
- Digital Audio Effects Question 9: Limiter/Compressor/Expander
- Digital Audio Effects Question 11: Reverb (Schroeder)
  - schroeder2.m
  - reverb_schroeder_eg.m
- Digital Audio Effects Question 12: Reverb (Moorer)
  - moorer.m
  - reverb_moorer_eg.m
- Digital Audio Effects Question 13: Reverb (Convolution)
  - reverb_convolution_eg.m
  - fconv.m
  - Impulse Response Sources:
    - http://www.voxengo.com/impulses
    - http://www.cksde.com/p_6_250.htm

Tutorial/Lab Class 5 (Week 6)

Tutorial Notes: MATLAB Graphics, Images and Video Formats (PDF)
- For videos embedded in this PDF, download lecture zip file. Install all the media in the same directory all the PDFs.
Lab 5 (Week 6): MATLAB Graphics, Images and Video Formats (PDF)
- All Lab MATLAB code: Graphics.zip
- Question 1: Dithering
  - dither_q1_hint.m Some example code (with a very stupid dithering pattern,for illustration). Your task is to replace this dithering pattern with a more suitable one (or try a few variations)
  - dither_demo.m Built in MATLAB dither function example.
  - lena.bmp Sample image.
- Question 2: Colour maps
  - rgb_eg.m Example code.
  - parrots.gifSample image.
- Questions 3-6: Chroma subampling. Example code:
- Question 7: Video aliasing
  - aliasing_wheel.m
    spokes.gif,
    spokesR.gif (Support images needed for aliasing_wheel.m)
  - raster_aliasing.m,
    barbara.gif (Support image needed for raster_aliasing.m)

Tutorial/Lab Class 6 (Week 7)

Lab 6 (Week 7): Basic Compression in MATLAB (PDF)
- All Lab MATLAB code: basic_compression_lab.zip
- Question 2: Entropy Coding
  - ent.m Computes Shannon's entropy.
  - probs.m Estimates probabilities by counting frequencies.
  - coin.m The entropy of a biased coin experiment.
  - huffman.m Huffman coder.
  - shannon_fano.m Shannon-Fano coder.
  - engfreq.m Relative frequencies of English letters.
  - arith_vs_huffman.m An experiment to compare the performance of Huffman vs Arithmetic Coding.
- Question 3: LZW Algorithm
  Original demo by Giuseppe Ridino:
  - lzw_demo1.m LZW compression demo.
  - norm2lzw.m LZW compressor.
  - lzw2norm.m LZW decompressor.
  Improved version (better output):
  - lzw_demo.m LZW compression demo.
  - lzw_compress.m LZW compressor.
  - lzw_decompress.m LZW decompressor.
  - add_code.m lookup_code.m Utility functions to add and look up codes in the dictionary.
- Question 4: Basic Transform Coding
  - simpletrans.m Basic example of image transform to decorrelate adjacent pixels.
  - simpletransquant.m Same as above but with quantisation.
  - bwt.m, ibwt.m Forward and inverse Burrows-Wheeler transform.

Tutorial/Lab Class 7 (Week 8)

Lab 7 (Week 8): DCT and JPEG in MATLAB (PDF)
- All Lab MATLAB code: dct_jpeg.zip
- Question 2: Basic Transform Coding (continued from last lab)
  - simpletrans.m Basic example of image transform to decorrelate adjacent pixels.
  - simpletransquant.m Same as above but with quantisation.
- Question 3: Discrete Cosine Transform
  - DCT1Deg.m 1D DCT demo.
  - dctlines.m Approximating lines with DCT.
  - dct2basis.m Display 2D DCT basis images.
  - dct2manual.m 2D DCT as a matrix multiplication (vectorisation of basis images).
  - dctenergy.m Illustration of the energy compaction with DCT.
  - gibbs1.m, gibbs2.m Gibbs phenomenon in 1D and 2D.
  - dctdemo.m Using DCT to compress an image demo.
- Question 4: JPEG compression
  - im2jpeg.m, jpeg2im.m, JPEG encoder/decoder.
  - mat2huff.m, huff2mat.m, Huffman encoder/decoder.

Tutorial/Lab Class 8 (Week 9)

Lab 8 (Week 9): Motion Compensation and I, B, P-frames (PDF)
- All Lab MATLAB code: mpeg.zip
  (This demo is by International Hellenic University. However, please download the above local copy as it is patched to work on Macs/Unices.)
- Sample videos:

Some Additional Tutorial Notes on Compression

Good Overview of all compression algorithms and JPEG/MPEG Video (External Link)
The JPEG Compression Standard (External Link)
A good overview of MPEG Video (External Link)
The MPEG-2 Video Compression Standard (External Link)
MPEG video compression technique (External Link)
MP3 Audio and AAC Compression Explained (External Link)
MPEG AUDIO Tutorial (External Link)