Diapositiva 1 - basilissachin
Skill Area 322:
Develop Various Multimedia
Objects
Multimedia and Web Design
(MWD)
322.3 Produce Audio File (8hrs)
322.3.1 – Need for Digitizing
Sound
322.3.1 – Process of recording
and editing digital sound
322.3.3 – Types of audio format
322.3.4 – Acquire graphics
through various means
What is digital audio?
 Audio is another meaning for sound.
 Digital audio refers to a digital
representation of the audio waveform for
processing, storage or transmission in
digital format.
Audio in Multimedia
• To enhance graphics, images, text,
narrations, voiceovers etc.
• Consequently,
the
power
of
communication and interactivity via the
audio interface will bring us an even
closer relationship with the computer.
• “It is the result of interactions between
images, music, the spoken text, sound
effects etc.
• Good audiovisual is therefore a language
of synthesis.” (Ferrés P., Joan.1998:118)
Audio in Multimedia (cont)
• A good synthesis, where the
expressive elements interact well,
are demonstrated by the fact that
the
receiver
has
a
unified
experience”. (Ferrés P., Joan.1998:118)
How does it work?
• Digital recording and reproduction converts
the analog sound signal picked up by the
microphone to a digital form by a process of
digitization, allowing it to be stored and
transmitted by a wider variety of media.
• Digital recording stores audio as a series of
binary numbers representing samples of the
amplitude of the audio signal at equal time
intervals, at a sample rate high enough to
convey all sounds capable of being heard.
How does it work? (cont)
 Digital recordings are considered higher quality
than analog recordings not necessarily because
they have higher fidelity (wider frequency
response or dynamic range), but because the
digital format can prevent much loss of quality
found in analog recording due to noise and
electromagnetic interference in playback, and
mechanical deterioration or damage to the
storage medium.
 A digital audio signal must be reconverted to
analog form during playback before it is applied
to a loudspeaker or earphones.
How does it work?
Analog
Signal
Digital
Signal
Converter
Analog
Signal
Converter
microphone
RECORD
Radio
PROCESS (CONVERSION)
PLAYBACK
Figure 1. Audio Processing
Audio Format
• Audio Formats can be broken down
into three main categories:
1. Uncompressed format
2. Lossless compression format
3. Lossy compression format
Uncompressed Format
 Often referred to as PCM formats
 Formats that use no compression.
 This means all the data is available, at
the risk of large file sizes.
 A WAV audio file is an example of an
uncompressed audio file.
Loseless Compression Format
 Applies compression to an uncompressed
audio file.
 It does not lose information or degrade
the quality of the digital audio file.
 The WMA audio file format uses lossless
compression.
Lossy Compression Format
 Results in some loss of data as the
compression
algorithm
eliminates
redundant or unnecessary information.
 However, lossy compression has become
popular online because of its small file
size.
 It is easier to transmit over the Internet.
 MP3 and Real Audio files uses a lossy
compression.
Audio Format Types
Uncompressed
format
Loseless Compression
Format
Lossy Compression
Format
WAV
FLAC
MP3
AIFF
Monkey's Audio (APE)
Vorbis
AU
WavPack (WV)
Musepack
PCM
TTA
AAC
ATRAC Advanced
Lossless
ATRAC
Apple Lossless (m4a)
Windows Media Audio
Lossy (WMA lossy)
MPEG
Windows Media Audio
Lossless (WMA
Lossless)
Shorten (SHN)
Windows Compatible Audio
Format
• MP3 (.mp3)
 MP3 is the name of the file extension and also
the name of the type of file for MPEG audio
layer 3.
 Layer 3 is one of three coding schemes (layer
1, layer 2 and layer 3) for the compression of
audio signals. Layer 3 removes all superfluous
information (more specifically, the redundant
and irrelevant parts of a sound signal).
 The result in real terms is layer 3 shrinks the
original sound data from a CD (with a bit rate
of 1411.2 kilobits per one second of stereo
music) by a factor of 12 (down to 112128kbps) without sacrificing sound quality.
Windows Compatible Audio
Format (cont)
• WMA - Windows Media Audio (.wma)
 Short for Windows Media Audio, WMA.
 A Microsoft file format for encoding digital
audio files similar to MP3 though can
compress files at a higher rate than MP3.
 WMA files, which use the .wma file extension,
can be of any size compressed to match many
different connection speeds, or bandwidths.
Windows Compatible Audio
Format (cont)
• WAV (.wav)
WAV is the format used for storing sound
in files developed jointly by Microsoft
and IBM.
It is a de facto standard for sound on PCs.
WAV sound files end with a .wav
extension and can be played by nearly all
Windows applications that support
sound.
Windows Compatible Audio
Format (cont)
 Real Audio (.ra .ram .rm)
 Real Audio is a proprietary format, and is
used for streaming audio that enables
you to play digital audio files in real-time.
 To use this type of file you must have
RealPlayer (for Windows or Mac), which
you can download for free.
Audio
was
developed
by
 Real
RealNetworks.
Windows Compatible Audio
Format (cont)
 MIDI - Musical Instrument Digital Interface
(.mid)
 Short for musical instrument digital
interface.
 MIDI is a standard adopted by the electronic
music industry for controlling devices, such
as synthesizers and sound cards, that emit
music.
 At minimum, a MIDI representation of a
sound includes values for the note's pitch,
length, and volume. It can also include
additional characteristics, such as attack and
delay time.
Windows Compatible Audio
Format (cont)
• Ogg (.ogg)
 Ogg is an audio compression format,
comparable to other formats used to
store and play digital music,
 Differs in that it is free, open and
unpatented.
 It uses Vorbis, a specific audio
compression scheme that's designed to
be contained in Ogg.
Basic requirements for audio
recording setup
• Microphone
• Audio recording & editing
software
• Speaker
• Monitor
• Mouse
• Sound card
• Audio mixer (optional)
• Earphones or headset (optional)
Audio recording applications
• Audio MP3 Sound Recorder
• Easy MP3 Recorder
• Audacity
• Nero Wave Editor 4
• Macromedia Sound Edit
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