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MMGD0203 Multimedia DesignMMGD0203MULTIMEDIA DESIGNChapter 4Sound and Video1
MMGD0203 Multimedia DesignSound and VideoTopics: Introduction to SoundHow is Sound Produced?SamplingStoring Audio DataFile FormatIntroduction to VideoAdvantages of Digital VideoVideo File Format2
MMGD0203 Multimedia DesignSoundIntroduction to Sound Sound is the best way to attract attention. Often audio provides the only effective way to conveyan idea, elicit an emotion, or dramatize point. Sounds also can be combined in a multimediapresentation to provide information and enhance theother media being presented.3
MMGD0203 Multimedia DesignSoundWhy Sound is Important in Multimedia? To reinforce message or themeTo set the moodTo catch the interest of the audienceTo alert the audienceTo include narration: effective for training andeducational application.4
MMGD0203 Multimedia DesignSoundTypes of Sound Music– Background– Attention grabber– Sound effect Speech– Narration– Instruction5
MMGD0203 Multimedia DesignSoundSound Wave Characteristics Two main characteristic in sound waves areFREQUENCY and AMPLITUDE. Frequency in the number of cycles a sound wavecreates in one second. A cycle is measured from one wave peak to another. The standard measurement for frequency is calledHERTZ (Hz).6
MMGD0203 Multimedia DesignSoundSound Wave Characteristics Amplitude is the volume or loudness a particularsound makes. The louder the sound, the higher the amplitude willbe. The unit of measure for loudness or volume is decibel(dB).7
MMGD0203 Multimedia DesignSoundSound Wave Characteristics8
MMGD0203 Multimedia DesignSoundDigital Sound Refers to the reproduction and transmission of soundstored in a digital format. The digitizing and storage of sound or music on acomputer or compact disc.9
MMGD0203 Multimedia DesignSoundConversion A digital audio signal starts with an analog-to-digitalconverter (ADC) that converts an analog signal to adigital signal. After being sampled with the ADC, the digital signalmay then be altered in a process which is calleddigital signal processing The digital audio signal may then be stored ortransmitted. The last step for digital audio is to be converted backto an analog signal with a digital-to-analogconverter (DAC).10
MMGD0203 Multimedia DesignSoundConversion11
MMGD0203 Multimedia DesignSoundSampling Process In order for a computer to work with audio waves,they must be converted from analog to digital form. This is done through a process called sampling, inwhich every fraction of a second a sample of theaudio is recorded in digital bits There are two factors that affect the quality of thedigitized audio:– Sample rate– Sample size12
MMGD0203 Multimedia DesignSoundSample Rate Sample rate is the number of times the sample istaken. The three most common sample rates are; 11.025kHz, 22.05 kHz, and 44.1 kHz. The higher the sample rate, the more samples thatare taken and, thus, the better the quality of thedigitized audio.13
MMGD0203 Multimedia DesignSoundSample Rate14
MMGD0203 Multimedia DesignSoundSample Size Sample size is the amount of information storedabout the sample. The two most common sample sizes are 8 bit and 16bit. An 8-bit sample allows 256 values that are used todescribe audio, whereas a 16-bit sample provides 65,536 values. The greater the sample size, the better the quality ofthe audio.15
MMGD0203 Multimedia DesignSoundSample Size Table below shows the file size (in bytes) for 10seconds of digital audio given various sample ratesand bit values.Sample Rate44.1 kHz44.1 kHz22.05 kHz22.05 kHz11.025 kHzBit Value1681688Size of File1.76 MB882 KB882 KB440 KB220 KB16
MMGD0203 Multimedia DesignSoundChannel Two types:– Monophonic– Stereophonic17
MMGD0203 Multimedia DesignSoundChannel - Monophonic Commonly called mono sound, mono, or non-stereosound, this early sound system used a single channelof audio for sound output. Monophonic sound is the most basic format of soundoutput. Mono (monophonic, or monaural) is sound from asingle source. All speakers in a mono system (like an intercom) willcarry the same signal.18
MMGD0203 Multimedia DesignSoundChannel - Monophonic19
MMGD0203 Multimedia DesignSoundChannel - Stereophonic Commonly called stereo sound or just stereo,stereophonic sound divides sounds across twochannels (recorded on two separate sources) thenthe recorded sounds are mixed so that someelements are channeled to the left and others to theright. Stereo (stereophonic) is sound from two sources,ideally spaced apart, and reproduces sound the waywe hear it naturally, with two ears.20
MMGD0203 Multimedia DesignSoundChannel - Stereophonic21
MMGD0203 Multimedia DesignSoundStoring Sound Data There are two means of storing sound data:– Waveform Audio (or digital audio) Example– Musical Instrument Digital Interface (MIDI). Example22
MMGD0203 Multimedia DesignSoundFile Formats Wav audio (.wav)Sound (.snd)Real audio (.ra, rm)Audio File Format (.aif)MIDI (.mid)MP3 audio (.mp3)Windows Media (.wma)23
MMGD0203 Multimedia DesignSoundCalculate Sound File SizeSound File Size Sample rate x sample size x channel x duration24
MMGD0203 Multimedia DesignSoundCalculate Sound File SizeExample 1:Calculate how much storage space is needed to record a16-bit, 44.1khz, stereo music for a duration of 30seconds.Sound file size 44100 x 2 x 2 x 30 5292000 bytes25
MMGD0203 Multimedia DesignSoundCalculate Sound File SizeExample 2:Calculate how much storage space is needed to record a8-bit, 11khz, mono sound for a duration of 10 seconds.Sound file size 11000 x 1 x 1 x 10 110000 bytes26
MMGD0203 Multimedia DesignSoundGuidelines Consider the appropriateness of using sound. Start with the highest-quality sound available andreduce the file size by converting the audio file to acompressed format. Consider using sound and still images as an alternativeto video to reduce file sizes. If appropriate, provide a way to give the user somecontrol over the audio.27
MMGD0203 Multimedia DesignVideoVideo Video is the technology ofelectronically capturing, recording,processing, storing, transmitting,and reconstructing a sequence ofstill images representing scenesin motion. Video makes use of all of theelements of multimedia, bringingyour products and services alive,but at a high cost.28
MMGD0203 Multimedia DesignVideoVideo The advantage of integrating video into a multimediapresentation is the capacity to effectively convey a greatdeal of information in the least amount of time.29
MMGD0203 Multimedia DesignVideoVideo Video is also very hardware-intensive (require thehighest performance demand on your computer)– Storage issue: full-screen, uncompressed videousesover 20 megabytes per second (MBps) ofbandwidth and storage space.– Processor capability in handling very huge data onreal time delivery30
MMGD0203 Multimedia DesignVideoDigitizing the Video Signal Analogue video is essentially a product of thetelevision industry and therefore conforms totelevision standards. Digital video is a product of the computing industryand therefore conforms to digital data standards.31
MMGD0203 Multimedia DesignVideoDigitizing the Video Signal Is usually recorded and played as an analog signal. It must therefore be digitized in order to beincorporated into a multimedia title.32
MMGD0203 Multimedia DesignVideoDigitizing the Video Signal33
MMGD0203 Multimedia DesignVideoAdvantages of Digital Video One of the advantages of digitized video is that it canbe easily edited. The video is stored as a standard computer file. Software motion video does not require specializedhardware for playback. Digital video requires neither a video board in thecomputer nor an external device (which adds extracosts and complexity) such as a videodisc player. Long-lasting.34
MMGD0203 Multimedia DesignVideoDisadvantages of Digital Video Requires large storage capacity devices.Copies can be made illegally.Need fast computer system for playback and capture.Requires knowledge of digital compressiontechnology.35
MMGD0203 Multimedia DesignVideoFile Size Considerations Digitized video files can be extremely large. A single second of high-quality color video that takesup only one-quarter of a computer screen can be aslarge as 1 MB. Several elements determine the file size:– Frame Rate– Image Size– Color Depth– the length of the video36
MMGD0203 Multimedia DesignVideoVideo Compression Because of the large sizes associated with videofiles, video compression/decompression programs,known as codecs, have been developed. These programs can substantially reduce the size ofvideo files, which means that more video can fit on asingle CD and that the speed of transferring videofrom a CD to the computer can be increased.37
MMGD0203 Multimedia DesignVideoDigital Video File Formats Motion Pictures Expert Group (.mpg)Quicktime (.mov)Audio Video Interleaved(.avi)Windows Media Video (.wmv)Adobe Flash video (.flv)38
MMGD0203 Multimedia DesignVideoCalculate Video File SizeVideo File Size Frame size x Frame rate x color depth x durationNotes (Color depth) : B&W video 1 byteColor video 3 bytes39
MMGD0203 Multimedia DesignVideoCalculate Video File SizeExample 1:Calculate the file size for a video with 320 x 240 pixels,color video, 30 fps, and length 15 seconds.Video file size 320 x 240 x 3 x 30 x 15 103680000 bytes40
MMGD0203 Multimedia DesignVideoCalculate Video File SizeExample 2:Calculate the file size for a video with 300 x 200 pixels,black and white video, 25 fps, and length 30 seconds.Video file size 300 x 200 x 1 x 25 x 30 45000000 bytes41
MMGD0203 Multimedia DesignVideoGuidelines Reducing the color depth to less than 256 colorsgives a markedly poorer-quality image. In most multimedia titles, you do not need to showfull-screen video. Reducing file size to minimize the use of video in theimage that appears on the screen.42
MMGD0203 Multimedia DesignLab Exercise:1.Using online wave editor:https://www.filelab.com/audio-editor2.Using online video editor:http://www160.lunapic.com43
of audio for sound output. Monophonic sound is the most basic format of sound output. Mono (monophonic, or monaural) is sound from a single source. All speakers in a mono system (like an intercom) will . Adobe Flash video (.flv) MMGD0203 Multimedia Design 39 Video
