Audio Production Techniques for the Internet
University of Helsinki
August 2002
Lecture outline
Kai Lassfolk
Updated 2002-08-19
Introduction
- Two-day course on audio production
- Basic audio recording, editing and publishing techniques
- Hands-on approach
- Includes a theoretical introduction and practical workshops and demonstrations
Schedule
Monday 19th
Place: Porthania, 6th floor, multimedia class
- 10-12: Introductory lecture
- 13-15: Sound editing
Tuesday 20th
Place: Department of Musicology, studio, Vironkatu 1, floor 1b
- 10-12: Recording studio techniques
- 13-15: Studio workshop
Stages of an audio production
- Preproduction
- General planning (budjetting etc.)
- Music composition
- Script preparation
- Rehersal
- Production
- Recording sessions
- Cue mixing
- Postproduction
- Editing
- Effects processing
- Mixing
- Mastering
- Encoding for distribution
Equipment, software etc.
Hardware:
- Musical instruments
- Microphone(s)
- Microphone preamplifier
- Mixer
- Recorder or AD-converter
- Computer with audio I/O for recording/editing
- Sound monitoring equipment (loudspeakers and/or headphones)
- Sound processing devices: reverb unit, compressor etc.
Software:
- Notation/composition software
- Recording/editing software ("tracking")
- Mastering software ("tracking")
- Effect plugins (reverb, compossion, tone control)
Sound recording and processing techniques
- Use and choise of acoustics
- Use and choise of microphones
- Use of other recording equipment
- Editing and arranging
- Effects processing
- Reverberation and echo
- Loudness control, dynamics processing: normalization, gain control, compression
- Tone control (equalization)
- Distortion/coloration: overdrive, phase shifting etc.
- Mixing
- Mastering
- Encoding for distribution (CD, MP3 etc.)
Net-based audio distribution formats
- Static audio files vs. dynamic streaming methods
- Audio only vs. multimedia/video formats
- Compression for reducing netowrk bandwidth requirements
- Acoustic vs. synthetic encoding/compression methods
Qualitative requirements:
- Understandability on speech signals
- Enjoyableness on musical signals
- Precision in professional distribution formats
Pulse code modulated audio signal (PCM)
- An analog audio signal is sampled at a constant rate
- Sampling rate determines frequency range
- Samples are given a numerical value (quantization)
- Quantization resolution (numer of bits per sample) determines signal to noise ratio
- Number of audio channels determines the ability to reproduce space
Pulse code modulation is used commonly in recording and sound processing
as well as in Audio CD:s.
Compressed audio and musical signal
- Aimed at optimizing sound quality vs. transmit time/storage space
- Based on aither a sound synthesis or an analysis-synthesis technique
- Psychoacoustical models are used to extract significant data
Internet-based audio distribution formats
- Uncompressed sound files (AU/SND, AIFF, WAV, CDR/CDDA, raw)
- Real Audio (www.real.com)
- MP3 (www.mpeg.org)
- Ogg Vorbis (www.vorbis.com)
- MIDI Files (www.midi.org)
- MPEG-4: AAC, Sctructured Audio (SA) (www.mpeg.org)
- MPEG-7
- Tracker-files (e.g. www.scene.org)
- QuickTime and other video formats (quicktime.apple.com)
Sound exmaples: J.S.Bach; Partita E major, Gavotte en rondeau (excerpt),
Sirkka Väisänen, violin.
Sound editing with Audacity
Audacity is a free, multiplatform sound editor
available at
audacity.sourceforge.net.
Example data for sound editing examples can be found
here.