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ia Systems
520251: Multimed




            Êส‹‹Çว¹น»ปÃรÐะ¡กÍอºบÁมÑัÅลµตÔิÁมÕีàเ´ดÕีÂย
                                    [àเÊสÕีÂย§ง]
                              6 ÊสÔิ§งËหÒา¤คÁม 2555




                                                          1
Agenda
• Properties of sound
• Analog audio
• Digital audio
• Audio file formats
• Sound recording
• Sound editing

                        2
Introduction

• Audio is the reproduction of sound - important
  means of communication.
• There are a number of advantages of using
  audio.
 • most obvious: interface for visual disabilities

                                                     3
Properties of Sound

          • Sound is a pressure
            wave created by
            successively vibrating
            matter back and forth.
          • The sound wave is in
            the form of a sine
            wave.



                                     4
Frequency
• The number of air pressure oscillations per
  second at a fixed point by a sound wave
• Measured in Hertz (Hz) - number of waves per
  second
• Audible range (human) = 20 Hz - 20 kHz
 • this is where the sensation of pitch
   originates


                                                 5
Frequency & Pitch
Frequency


              Pitch
Frequency


              Pitch




                                6
Wavelength
• The distance between waves




                               7
Amplitude


     • The height of the
       wave
     • Measured in decibels
       (dB or dBA)




                              8
Intensity vs. Loudness
• Amplitude can be thought of as the intensity of
  sound and is measurable.

• Loudness of sound is a perception.
 • Sound can be perceived differently at the various
    frequencies (1 kHz-4 kHz is more sensitive than
    the lower and the higher)

 • Individuals also have different hearing capacities.
    What is loud to one person may not be loud to
    another, which why loudness is a perception and
    cannot be measured.

                                                         9
dBA                        Sound
  10      Normal breathing
  20      Whispering at 5 ft
  30      Soft whispering
  50      Rainfall
  60      Normal conversation
 110      Shouting in the ear
 120      Thunder
110-120   Rock concert
 130      Air raid
 180      Rocket launching from pad


                                      10
Analog Audio

• analog = the
  measurement of
  continuous change or
  movement over a
  period of time




                            11
Digital Audio
• The reproduction of sound using digital
  information




• The value of the signal is sampled at regular
  intervals by an analog-to-digital converter
  (ADC)

                                                  12
Basic Terminology &
        Properties of DA
• Channels
• Sampling rate
• Bit depth
• Quality and file size
• Compression
• Audio codecs

                             13
Channels
           Stereo


                              e s se d l
                      c om p r i le w i l
              An u n gi t a l f
                  e o di e s i ze o f a
            s te r c e t h
             b e t w i n o f i le .
                      mo



           Mono



                                            14
Sampling Rate
• ADC - the signal is sampled at regular intervals
• The value of each sample is rounded to the
  nearest integer in a scale that varies according
  to the resolution of the signal




                                                     15
Sampling Rate

• The accuracy the
  reproduction to
  the source
  depends on how
  often the sample is
  taken.




                            16
Common DA Sampling Rate
           8,000 Hz telephone, adequate for human speech

          22,050 Hz radio

          32,000 Hz miniDV digital camcorder

                    CD, commonly used with MPEG-1 audio
          44,100 Hz
                    (VCD, SVCD, MP3)

                    digital sound used for digital TV, DVD, DAT,
          48,000 Hz
                    films and professional audio

96,000 or 192,400 Hz DVD-audio and HD-DVD audio tracks


                                                                   17
Bit Depth
• The number of bits used to describe each of
  the samples taken from the sampling rate
 • the potential accuracy of a digital audio
• Higher bit-depth audio will sound better
  than lower one




                                                18
Quality & File Size
• Make the highest level (if possible) ~ 16-bit
  44kHz Stereo
 • this produces a large file size, however, high
   audio clarity
• Chances to manipulate such file (to make it
  smaller) :
 • reduce the sampling rate
 • make it mono
                                                   19
20
Compression
                                Audio
                                Quality
                                                       “later editing”
• Digital audio files can also
  be compressed to reduce                                Lossless
  file size                                                  WMA

                                          Lossy
 • MPEG-1 Audio layer-3                     MP3
                                          Real Audio
   (MP3) is a common
                                     “transmission”

                                                                  File Size



                                                                              21
Audio Codecs
 • An audio codec             is a piece of software
                    (coder/decoder)

   or a driver that provides support for certain
   audio formats for certain system.



       codec x                        codec y
                                                ✘
Audio codecs                          codec x
                                                ✔      22
Audio File Formats
• An audio file format is a
  container format for storing
                                 • WAV format
  data on a computer system.       • Microsoft’s audio format
  • AIF format                     • also one of the mostthe
                                     common format on
    • developed by Apple
      Computer
                                     web

                                 • MP3
    • supported by most web
      browsers                     • most widespread form
                                     of audio on the Internet
  • AU format
                                   • playable on various
    • one of theformat on the
      common
                  most               players

       web

    • created by Sun
      Microsystems
                                                                23
24
MIDI Format
• Musical Instrument Digital Interface (MIDI) is
  typically used to play music.
• MIDI files contain a set of instruction that the
  computer sends to a sound card, synthesizer,
  or other device.
 • Such instructions (note and instrument
   description) describe how to play the sound,
   rather than recording an actual rendition of
   the sound.

                                                    25
26
Sound Recording




                  27
28
29
Sound Editing
• Audacity - it’s GNU GPL license, it’s free, it’s cross
  platform.

 • Tracks
 • Waveform display
 • Selection
 • Trim
 • Amplify
 • Pitch
 • and many more....
                                                           30
Digital Audio
Technologies & Applications




                              31
Portable Music Players



                         32
Before Digital
70s




                       33
CD on market (1982)

                       D ig i t al!
                I t ’s




                                      34
Not quite portable, is it?


                             35
Digital files?
Compress ‘em

       ATRAC         WMA

      CODECS
        MP3
      Vorbis (OGG)   AAC




                           36
Digital Audio Players
1997 - MPMan                        1998 - Rio PMP300
        SaeHan Infomation Systems          Diamond Multimedia




  Eiger Labs MPMAN F10 (1998)           32 MB Internal Memory
             32 MB                      SmartMedia Memory Slot


                                                                 37
Digital Audio Players
 2000 - Creative NOMAD Jukebox
       Creative Labs




          6 GB Harddisk
          $500


                                 38
The Revolution
     October 2001 - 1st iPod Introducing




                                           39
iPod Family




              40
41
42
Get quick and instant access to         Tune into all your favorite stations   Watch supported 720p HD movies,      Connect, update, and buy content    Surf the web anytime, anywhere
your content with multi-touch           with crystal-clear reception. With     TV shows and videos in high          wirelessly from Wi-Fi hot spots.    you have a Wi-Fi connection.
navigation. With a 3.3-inch screen      an integrated HD Radio receiver,       definition on your HDTV through      Stream millions of songs over Wi-   Enjoy your favorite websites with a
and vivid 16:9 OLED display             you can access a variety of HD         the Zune HD & AV Dock (sold          Fi directly to your Zune HD and     full-featured web browser including
(480x272 resolution), premium           Radio stations at no additional        separately). Or take them with you   turn it into a portable digital     tap-to-zoom technology, built-in
entertainment is at your fingertips.*   cost. Plus, tag the songs you like     for premium entertainment on the     jukebox.                            accelerometer, and touchscreen
                                        for later purchase.                    go. Additional dock and HDTV are                                         QWERTY keyboard.
                                                                               required.*




                                                                                                                                                                                              43
44
45
iTunes
+ iTunes Music Store



                       46
47
Online Music Stores



                      48
49
Podcast



          50
51
AudioBooks



             52
53
Text-to-Speech




                 54
สถิติผู้พิการ 2550




               ที่มา: สํานักงานสถิติแห่งชาติ

                                               55
DAISY (Digital Accessibility
  Information System)




                               56

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05 audio

  • 1. ia Systems 520251: Multimed Êส‹‹Çว¹น»ปÃรÐะ¡กÍอºบÁมÑัÅลµตÔิÁมÕีàเ´ดÕีÂย [àเÊสÕีÂย§ง] 6 ÊสÔิ§งËหÒา¤คÁม 2555 1
  • 2. Agenda • Properties of sound • Analog audio • Digital audio • Audio file formats • Sound recording • Sound editing 2
  • 3. Introduction • Audio is the reproduction of sound - important means of communication. • There are a number of advantages of using audio. • most obvious: interface for visual disabilities 3
  • 4. Properties of Sound • Sound is a pressure wave created by successively vibrating matter back and forth. • The sound wave is in the form of a sine wave. 4
  • 5. Frequency • The number of air pressure oscillations per second at a fixed point by a sound wave • Measured in Hertz (Hz) - number of waves per second • Audible range (human) = 20 Hz - 20 kHz • this is where the sensation of pitch originates 5
  • 6. Frequency & Pitch Frequency Pitch Frequency Pitch 6
  • 7. Wavelength • The distance between waves 7
  • 8. Amplitude • The height of the wave • Measured in decibels (dB or dBA) 8
  • 9. Intensity vs. Loudness • Amplitude can be thought of as the intensity of sound and is measurable. • Loudness of sound is a perception. • Sound can be perceived differently at the various frequencies (1 kHz-4 kHz is more sensitive than the lower and the higher) • Individuals also have different hearing capacities. What is loud to one person may not be loud to another, which why loudness is a perception and cannot be measured. 9
  • 10. dBA Sound 10 Normal breathing 20 Whispering at 5 ft 30 Soft whispering 50 Rainfall 60 Normal conversation 110 Shouting in the ear 120 Thunder 110-120 Rock concert 130 Air raid 180 Rocket launching from pad 10
  • 11. Analog Audio • analog = the measurement of continuous change or movement over a period of time 11
  • 12. Digital Audio • The reproduction of sound using digital information • The value of the signal is sampled at regular intervals by an analog-to-digital converter (ADC) 12
  • 13. Basic Terminology & Properties of DA • Channels • Sampling rate • Bit depth • Quality and file size • Compression • Audio codecs 13
  • 14. Channels Stereo e s se d l c om p r i le w i l An u n gi t a l f e o di e s i ze o f a s te r c e t h b e t w i n o f i le . mo Mono 14
  • 15. Sampling Rate • ADC - the signal is sampled at regular intervals • The value of each sample is rounded to the nearest integer in a scale that varies according to the resolution of the signal 15
  • 16. Sampling Rate • The accuracy the reproduction to the source depends on how often the sample is taken. 16
  • 17. Common DA Sampling Rate 8,000 Hz telephone, adequate for human speech 22,050 Hz radio 32,000 Hz miniDV digital camcorder CD, commonly used with MPEG-1 audio 44,100 Hz (VCD, SVCD, MP3) digital sound used for digital TV, DVD, DAT, 48,000 Hz films and professional audio 96,000 or 192,400 Hz DVD-audio and HD-DVD audio tracks 17
  • 18. Bit Depth • The number of bits used to describe each of the samples taken from the sampling rate • the potential accuracy of a digital audio • Higher bit-depth audio will sound better than lower one 18
  • 19. Quality & File Size • Make the highest level (if possible) ~ 16-bit 44kHz Stereo • this produces a large file size, however, high audio clarity • Chances to manipulate such file (to make it smaller) : • reduce the sampling rate • make it mono 19
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  • 21. Compression Audio Quality “later editing” • Digital audio files can also be compressed to reduce Lossless file size WMA Lossy • MPEG-1 Audio layer-3 MP3 Real Audio (MP3) is a common “transmission” File Size 21
  • 22. Audio Codecs • An audio codec is a piece of software (coder/decoder) or a driver that provides support for certain audio formats for certain system. codec x codec y ✘ Audio codecs codec x ✔ 22
  • 23. Audio File Formats • An audio file format is a container format for storing • WAV format data on a computer system. • Microsoft’s audio format • AIF format • also one of the mostthe common format on • developed by Apple Computer web • MP3 • supported by most web browsers • most widespread form of audio on the Internet • AU format • playable on various • one of theformat on the common most players web • created by Sun Microsystems 23
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  • 25. MIDI Format • Musical Instrument Digital Interface (MIDI) is typically used to play music. • MIDI files contain a set of instruction that the computer sends to a sound card, synthesizer, or other device. • Such instructions (note and instrument description) describe how to play the sound, rather than recording an actual rendition of the sound. 25
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  • 30. Sound Editing • Audacity - it’s GNU GPL license, it’s free, it’s cross platform. • Tracks • Waveform display • Selection • Trim • Amplify • Pitch • and many more.... 30
  • 31. Digital Audio Technologies & Applications 31
  • 34. CD on market (1982) D ig i t al! I t ’s 34
  • 35. Not quite portable, is it? 35
  • 36. Digital files? Compress ‘em ATRAC WMA CODECS MP3 Vorbis (OGG) AAC 36
  • 37. Digital Audio Players 1997 - MPMan 1998 - Rio PMP300 SaeHan Infomation Systems Diamond Multimedia Eiger Labs MPMAN F10 (1998) 32 MB Internal Memory 32 MB SmartMedia Memory Slot 37
  • 38. Digital Audio Players 2000 - Creative NOMAD Jukebox Creative Labs 6 GB Harddisk $500 38
  • 39. The Revolution October 2001 - 1st iPod Introducing 39
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  • 43. Get quick and instant access to Tune into all your favorite stations Watch supported 720p HD movies, Connect, update, and buy content Surf the web anytime, anywhere your content with multi-touch with crystal-clear reception. With TV shows and videos in high wirelessly from Wi-Fi hot spots. you have a Wi-Fi connection. navigation. With a 3.3-inch screen an integrated HD Radio receiver, definition on your HDTV through Stream millions of songs over Wi- Enjoy your favorite websites with a and vivid 16:9 OLED display you can access a variety of HD the Zune HD & AV Dock (sold Fi directly to your Zune HD and full-featured web browser including (480x272 resolution), premium Radio stations at no additional separately). Or take them with you turn it into a portable digital tap-to-zoom technology, built-in entertainment is at your fingertips.* cost. Plus, tag the songs you like for premium entertainment on the jukebox. accelerometer, and touchscreen for later purchase. go. Additional dock and HDTV are QWERTY keyboard. required.* 43
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  • 50. Podcast 50
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  • 55. สถิติผู้พิการ 2550 ที่มา: สํานักงานสถิติแห่งชาติ 55
  • 56. DAISY (Digital Accessibility Information System) 56