itmmsn02 | Multimedia sound

Waveform (WAV)

Digital sound

Using an Analog Digital Converter (ADC) sound may be digitised into your computer.
The ADC samples the electrical values of an analog sound wave and records them as numerical units. Most editing software display sounds in waveforms to assist editing.

Sound comes in a variety of formats, and within each format you can specify different settings.
Resource Interchange File Format (RIFF)
- A Microsoft developed format capable of handling digital audio and MIDI.
WAV (waveform)
- Developed by Microsoft as a subset of the RIFF format, comes standard with MS-Windows supporting Mono-stereo, 8 or 16-bit audio.
- Windows wave files, the standard settings (work with a PC-Speaker Driver -PCM 11,025Hz 8bit Mono)

MPEG level 3
- An open compression standard, designed for storing digital sounds suitable for the Internet.

SDMI (Secure Digital Music Interface)
- Standard released July 13, 1999. Designed to protect against most forms of unauthorised copying.

SND (sound)
- Used by Apple Macintosh (with interpreters for the PC available) limited to 8 bits.

MOV (movie)
- Used by Apple Macintosh (with interpreters for the PC available). Basically a video format where the pictures are omitted.

Audio Interchange File Format (AIFF, AIF)
- Used by Macintosh, IBM compatibles, Comodore Amiga & Silicon Graphics computers. Allows a large number of sampling rates up to 32 bits

Sun Audio (AU)
- Developed by Sun Microsystems, uses a 16-bit compressed audio format.

VOC (voice)

Creative labs voice format for the Sound Blaster card. Supports 8-16 bits wit/without compression.

Note: Programs like Director 7 allow for internal file types. In Directors case Shockwave Audio (SWA), where a compression ratio of up to 176 to 1 is possible.

Wav is the extension used for files containing digitized analog sound using a microphone, sampler etc...
Microsoft developed it not much after they launched windows 3.0 in 1985.
Wav files are normally large in size depending on length, whether its recorded in stereo or mono and the sampling rate used.
An advantage of digitizing sound is that it gives as a visual display of the file.(see diagram above).

The main use for wave is in the recording studio as it out does the need for reel to reel (analogue tape), it is a near prefect storage medium & it enables users to visually edit there sounds and copy and paste with ease.
Most soundcards in today's computers are capable of playing back and recording stereo16-bit sound sampled at 44kHz. 32 bit and 64 bit sound cards are emerging.
The sample rate of 44kHz at 11kHz is relevant to the sound quality and Mb taken up per seconds

Channels: Mono or stereo
Sound level - ensure all sounds are normalised
Sampling rates:
Voice 11kHz
Tape Quality 22kHz
CD Quality 44kHz.
Sampling size:
8 bit = 256 steps in amplitude (sound effects),
16-bit (65,536 steps in amplitude (CD-quality audio)
Windows standard:
Mono 11KHz, 8bits
Samples : Voice & music (Dreaming - Schumann)
1. wavef.wav
  (324K , PCM 22,050 Hz, 8Bit, Mono)
2. wavef1.wav
  (162K , PCM 11,025 Hz, 8Bit, Mono)
3. wavef.mp3
  (MP3 of 1 above 177KB)