Week 11 : 23 April 2014
In class I understood the process involve in digitizing the Audio
Audio : Sound is perhaps the most element of multimedia. It can provide the listening pleasure of music, the startling accent of special effects or the ambience of a mood-setting background. Sound is the terminology used in the analog form, and the digitized form of sound is called as audio.Audio signals are continuous analog signals.
Input: microphones and then digitised and stored
CD Quality Audio requires 16-bit sampling at 44.1 KHz
Even higher audiophile rates (e.g. 24-bit, 96 KHz)
When something vibrates in the air is moving back and forth it creates wave of pressure. These waves spread like ripples from pebble tossed into a still pool and when it reaches the eardrums, the change of pressure or vibration is experienced as sound.
Acoustics is the branch of physics that studies sound. Sound pressure levels are measured in decibels (db); a decibel measurement is actually the ratio between a chosen reference point on a logarithmic scale and the level that is actually experienced.
Digital audio is created when a sound wave is converted into numbers – a process referred to as digitizing. It is possible to digitize sound from a microphone, a synthesizer, existing tape recordings, live radio and television broadcasts, and popular CDs. You can digitize sounds from a natural source or prerecorded. Digitized sound is sampled sound. Ever nth fraction of a second, a sample of sound is taken and stored as digital information in bits and bytes. The quality of this digital recording depends upon how often the samples are taken.
In class I understood on how to prepare Digitizing Audio Files
Preparing digital audio files is fairly straight forward. If you have analog source materials – music or sound effects that you have recorded on analog media such as cassette tapes.
The first step is to digitize the analog material and recording it onto a computer readable digital media. It is necessary to focus on two crucial aspects of preparing digital audio files:
o Balancing the need for sound quality against your available RAM and Hard disk resources.
o Setting proper recording levels to get a good, clean recording.
Remember that the sampling rate determines the frequency at which samples will be drawn for the recording. Sampling at higher rates more accurately captures the high frequency content of your sound. Audio resolution determines the accuracy with which a sound can be digitized.
In class I learned the quality of audio
The method for digitally encoding the high quality stereo of the consumer CD music market is an instrument standard, ISO 10149. This is also called as RED BOOK standard.
The developers of this standard claim that the digital audio sample size and sample rate of red book audio allow accurate reproduction of all sounds that humans can hear. The red book standard recommends audio recorded at a sample size of 16 bits and sampling rate of 44.1 KHz.MIDI is Musical Instrument Digital Interface. MIDI is a communication standard developed for electronic musical instruments
and computers.To make MIDI scores, however you will need sequencer software and a sound synthesizer.
In class I learned the formula for determining the size of the digital audio
Audio : Sound is perhaps the most element of multimedia. It can provide the listening pleasure of music, the startling accent of special effects or the ambience of a mood-setting background. Sound is the terminology used in the analog form, and the digitized form of sound is called as audio.Audio signals are continuous analog signals.
Input: microphones and then digitised and stored
CD Quality Audio requires 16-bit sampling at 44.1 KHz
Even higher audiophile rates (e.g. 24-bit, 96 KHz)
When something vibrates in the air is moving back and forth it creates wave of pressure. These waves spread like ripples from pebble tossed into a still pool and when it reaches the eardrums, the change of pressure or vibration is experienced as sound.
Acoustics is the branch of physics that studies sound. Sound pressure levels are measured in decibels (db); a decibel measurement is actually the ratio between a chosen reference point on a logarithmic scale and the level that is actually experienced.
Digital audio is created when a sound wave is converted into numbers – a process referred to as digitizing. It is possible to digitize sound from a microphone, a synthesizer, existing tape recordings, live radio and television broadcasts, and popular CDs. You can digitize sounds from a natural source or prerecorded. Digitized sound is sampled sound. Ever nth fraction of a second, a sample of sound is taken and stored as digital information in bits and bytes. The quality of this digital recording depends upon how often the samples are taken.
In class I understood on how to prepare Digitizing Audio Files
Preparing digital audio files is fairly straight forward. If you have analog source materials – music or sound effects that you have recorded on analog media such as cassette tapes.
The first step is to digitize the analog material and recording it onto a computer readable digital media. It is necessary to focus on two crucial aspects of preparing digital audio files:
o Balancing the need for sound quality against your available RAM and Hard disk resources.
o Setting proper recording levels to get a good, clean recording.
Remember that the sampling rate determines the frequency at which samples will be drawn for the recording. Sampling at higher rates more accurately captures the high frequency content of your sound. Audio resolution determines the accuracy with which a sound can be digitized.
In class I learned the quality of audio
The method for digitally encoding the high quality stereo of the consumer CD music market is an instrument standard, ISO 10149. This is also called as RED BOOK standard.
The developers of this standard claim that the digital audio sample size and sample rate of red book audio allow accurate reproduction of all sounds that humans can hear. The red book standard recommends audio recorded at a sample size of 16 bits and sampling rate of 44.1 KHz.MIDI is Musical Instrument Digital Interface. MIDI is a communication standard developed for electronic musical instruments
and computers.To make MIDI scores, however you will need sequencer software and a sound synthesizer.
In class I learned the formula for determining the size of the digital audio
- The sampling rate is how often the samples are taken.
- The sample size is the amount of information stored. This is called as bit resolution.
- The number of channels is 2 for stereo and 1 for monophonic.
- The time span of the recording is measured in seconds.
In class I understood Editing Digital Recordings
Once a recording has been made, it will almost certainly need to be edited. The basic sound editing operations that most multimedia procedures needed are described in the paragraphs that follow
1. Multiple Tasks: Able to edit and combine multiple tracks and then merge the tracks and export them in a final mix to a single audio file.
2. Trimming: Removing dead air or blank space from the front of a recording and an unnecessary extra time off the end is your first sound editing task.
3. Splicing and Assembly: Using the same tools mentioned for trimming, you will probably want to remove the extraneous noises that inevitably creep into recording.
4. Volume Adjustments: If you are trying to assemble ten different recordings into a single track there is a little chance that all the segments have the same volume.
5. Format Conversion: In some cases your digital audio editing software might read a format different from that read by your presentation or authoring program.
6. Resampling or downsampling: If you have recorded and edited your sounds at 16 bit sampling rates but are using lower rates you must resample or downsample the file.
7. Equalization: Some programs offer digital equalization capabilities that allow you to modify a recording frequency content so that it sounds brighter or darker.
8. Digital Signal Processing: Some programs allow you to process the signal with reverberation, multitap delay, and other special effects using DSP routines.
9. Reversing Sounds: Another simple manipulation is to reverse all or a portion of a digital audio recording. Sounds can produce a surreal, other wordly effect when played backward.
10. Time Stretching: Advanced programs let you alter the length of a sound file without changing its pitch. This feature can be very useful but watch out: most time stretching algorithms will severely degrade the audio quality.
In class I learned the many types of Audio File Formats
A file format determines the application that is to be used for opening a file. Following is the list of different file formats and the software that can be used for opening a specific file.
1. *.AIF, *.SDII in Macintosh Systems
2. *.SND for Macintosh Systems
3. *.WAV for Windows Systems
4. MIDI files – used by north Macintosh and Windows
5. *.WMA –windows media player
6. *.MP3 – MP3 audio
7. *.RA – Real Player
8. *.VOC – VOC Sound
9. AIFF sound format for Macintosh sound files
10. *.OGG – Ogg Vorbis
In class I learned the different software used for audio manipulation
Software such as Toast and CD-Creator from Adaptec can translate the digital files of red book Audio format on consumer compact discs directly into a digital sound editing file, or decompress MP3 files into CD-Audio. There are several tools available for recording audio. Following is the list of different software that can be used for recording and editing audio ;
a) Sound recorder from Microsoft
b) Apple’s QuickTime Player pro
c) Sonic Foundry’s Sound Forge for Windows
d) Soundedit16
In class I learned the Audio compression : The difference between lossless compression and lossy compression
Lossless compression, lets you recreate the original file exactly. All lossless compression is based on the idea of breaking a file into a "smaller" form for transmission or storage and then putting it back together on the other end so it can be used again. Lossless compression recreates a compressed file as an identical match to its original form. All lossless compression uses techniques to break up a file into smaller segments, for storage or transmission, that get reassembled later. Lossless compression is used for files, such as applications, that need to be reproduced exactly like the original file.
Lossy compression works very differently. These programs simply eliminate "unnecessary" bits of information, tailoring the file so that it is smaller. This type of compression is used a lot for reducing the file size of bitmap pictures, which tend to be fairly bulky. Lossy compression, on the other hand, eliminates repeated or "unnecessary" pieces of data. With lossy compression, you can't get the original file back after it has been compressed.
Once a recording has been made, it will almost certainly need to be edited. The basic sound editing operations that most multimedia procedures needed are described in the paragraphs that follow
1. Multiple Tasks: Able to edit and combine multiple tracks and then merge the tracks and export them in a final mix to a single audio file.
2. Trimming: Removing dead air or blank space from the front of a recording and an unnecessary extra time off the end is your first sound editing task.
3. Splicing and Assembly: Using the same tools mentioned for trimming, you will probably want to remove the extraneous noises that inevitably creep into recording.
4. Volume Adjustments: If you are trying to assemble ten different recordings into a single track there is a little chance that all the segments have the same volume.
5. Format Conversion: In some cases your digital audio editing software might read a format different from that read by your presentation or authoring program.
6. Resampling or downsampling: If you have recorded and edited your sounds at 16 bit sampling rates but are using lower rates you must resample or downsample the file.
7. Equalization: Some programs offer digital equalization capabilities that allow you to modify a recording frequency content so that it sounds brighter or darker.
8. Digital Signal Processing: Some programs allow you to process the signal with reverberation, multitap delay, and other special effects using DSP routines.
9. Reversing Sounds: Another simple manipulation is to reverse all or a portion of a digital audio recording. Sounds can produce a surreal, other wordly effect when played backward.
10. Time Stretching: Advanced programs let you alter the length of a sound file without changing its pitch. This feature can be very useful but watch out: most time stretching algorithms will severely degrade the audio quality.
In class I learned the many types of Audio File Formats
A file format determines the application that is to be used for opening a file. Following is the list of different file formats and the software that can be used for opening a specific file.
1. *.AIF, *.SDII in Macintosh Systems
2. *.SND for Macintosh Systems
3. *.WAV for Windows Systems
4. MIDI files – used by north Macintosh and Windows
5. *.WMA –windows media player
6. *.MP3 – MP3 audio
7. *.RA – Real Player
8. *.VOC – VOC Sound
9. AIFF sound format for Macintosh sound files
10. *.OGG – Ogg Vorbis
In class I learned the different software used for audio manipulation
Software such as Toast and CD-Creator from Adaptec can translate the digital files of red book Audio format on consumer compact discs directly into a digital sound editing file, or decompress MP3 files into CD-Audio. There are several tools available for recording audio. Following is the list of different software that can be used for recording and editing audio ;
a) Sound recorder from Microsoft
b) Apple’s QuickTime Player pro
c) Sonic Foundry’s Sound Forge for Windows
d) Soundedit16
In class I learned the Audio compression : The difference between lossless compression and lossy compression
Lossless compression, lets you recreate the original file exactly. All lossless compression is based on the idea of breaking a file into a "smaller" form for transmission or storage and then putting it back together on the other end so it can be used again. Lossless compression recreates a compressed file as an identical match to its original form. All lossless compression uses techniques to break up a file into smaller segments, for storage or transmission, that get reassembled later. Lossless compression is used for files, such as applications, that need to be reproduced exactly like the original file.
Lossy compression works very differently. These programs simply eliminate "unnecessary" bits of information, tailoring the file so that it is smaller. This type of compression is used a lot for reducing the file size of bitmap pictures, which tend to be fairly bulky. Lossy compression, on the other hand, eliminates repeated or "unnecessary" pieces of data. With lossy compression, you can't get the original file back after it has been compressed.