AUDIO Guruh Fajar Shidik, M.Cs

Profile Lecturer Name GURUH FAJAR SHIDIK, S.kom, M.Cs Place / Date Born PONTIANAK / 15 FEBRUARI 1987 Research Interest Artificial Intelligence, Algorithm Complexity, Image Processing, Machine Learning, Network Computing, Computer Security Home Based Post Graduate Information Technology Academic S1(2009) - Universitas Dian Nuswantoro (3.5 year) S2(2011)- University Teknikal Malaysia Melaka ( 1 year) S3(2012 ) - University Teknikal Malaysia Melaka ( Ongoing ) Publication Journal & Conference 2013 – Performance Analysis of interface Bonding and Channel Bonding at Point to Point, Journal IEEE Latin America Transaction 2013 – Performance Evaluation of Bonding Technique at Wireless 802.11n - Journal TELKOMNIKA 2013 – An Improve Technique of Color Histogram in Image Clustering Using Image Matting, Journal JATIT 2012 – Auto Level Color Correction For Underwater Image Matching Optimization, - Journal IJCSNS 2012 – Performance Enhancement of Image Clustering Using Singular Value Decomposition in Color Histogram Content-Based Image Retrieval –Jurnal IJCCE 2012 - Analisa Pengaruh Perbedaan Medium Air Dan Udara Terhadap Kalibrasi Kamera Dengan Menggunakan Metode Zhang, Semantik 2011 - Framework untuk Mendeteksi Bot Net Kraken dan Conficker pada Jaringan Komputer, Semantik International Technical Speaker 2012 - LASCCDCN Latin America Symposium on Clud Computing , Data Center and Network - MEXICO

Kontrak Kuliah UAS : 30% Project / Writing Test UTS : 30% Writing Test Tugas : 40% *Tugas Lewat dari deadline – NO MARK !! UTS 15% UAS 25% 5% Tugas 1 10% Tugas 2 5% Tugas 3 20% Project Presentation Guruh.fajar@research.dinus.ac.id 08574122932

Introduction What is Sound? Sound is a wave phenomenon like light, but is macroscopic and involves molecules of air being compressed and expanded under the action of some physical device. Is a form of energy produced & transmitted by vibrating matter Travels in waves Travels more quickly through solids than liquids or gases

Vibration Back and forth movement of molecules of matter

Compression Where molecules are being pressed together as the sound waves move through matter For example, a wave travels through the springs just like sound waves travel through the air the places where the springs are close together are like compressions in the air.

Sound Waves Alternating areas of high & low pressure in the air ALL sound is carried through matter as sound waves Sound waves move out in ALL directions from a vibrating object

Wavelength & Frequency Wavelength is the distance between one part of a wave and the same part of the next wave Frequency is the number of waves moving past a point in one second

Pitch A measure of how high or low a sound is. Pitch depends on the frequency of a sound wave For example, Low pitch Low frequency Longer wavelength High pitch High frequency Shorter wavelength

Volume Amount of sound energy reaching your ears Depends on: How far the vibrating object is moving as it goes back and forth How far you are from the source of a sound Volume Control

Sound and Instruments Instruments can be played at different pitches by changing lengths of different parts. For example, Another way to make different pitches is to change the thickness of the material that vibrates.

Format Audio

3 Categories of Audio Files There are 3 categories in which certain Audio files belong to. Uncompressed: Audio files that are not compressed and are capable of having a large file size. Ex) .Wav Lossless: Audio files that are compressed but doesn’t lose any quality to the file. Ex) .WMA Lossy: Audio files that lose some quality when being compressed. Ex) .Mp3

Most common audio files The most common types of audio files that are still being used today are .Wav files and .Mp3 files. Mp3 files are the most popular because it’s used for downloading and storing music into your computer, CD player, or mp3 player. Wave files are used for storing CD-quality sound files, which can be large in size.

Digital Audio – File Formats Apple Audio Interchange File Format – AIFF .AIF or .AIFF or .AIFC 8-bit, mono 8-bit, stereo 16-bit, mono 16-bit, stereo 32-bit, mono 32-bit, stereo

Apples sound formats Sound .AIF files support a range of sampling rates 8kHz, 11kHz, 22kHz, 44kHz and 48kHz compression of between 2 to 1 and 4 to 1 is available using suitable codecs but causes reduction in sound quality .AIFC is AIFF with IMA compression Sound .SND

Other platforms SUN Sun Audio - (NeXT Audio) .AU .AU files support only 8kHz, 11kHz and 44kHz sampling rates 8-bit, mono 8-bit, stereo u-law, mono u-law, stereo A-law, mono A-law, stereo Java/Web, mono

Windows Wave and PCM Adaptive Delta Pulse Code Modulation – ADPCM CCITT All WAV (sometimes .PCM for PCM files) µ-law, mono µ-law, stereo A-law, mono A-law, stereo IMA ADPCM 8kHz, 4-bit, mono IMA ADPCM 8kHz, 4-bit, stereo IMA ADPCM 8kHz, 8-bit, mono IMA ADPCM 8kHz, 8-bit, stereo IMA ADPCM 8kHz, 16-bit, mono IMA ADPCM 8kHz, 16-bit, stereo

Windows sound formats continued .WAV files support a range of sampling rates 8kHz, 11kHz, 22kHz, 44kHz and 48kHz also a version with Microsoft’s own compression algorithm Can exceed CD quality Higher quality – Greater storage penalty

Windows Media Audio A streaming audio format Designed for network transfer and play- before-download replay Available for UNIX, Mac and Windows Formats: .asf, .wma, .wmv wide range of quality options

Real Audio A streaming audio format Designed for network transfer and play- before-download replay Available for UNIX, Mac and Windows Formats: .RA also as part of .RM, .RAM wide range of quality options

Other Streaming Formats In addition there are other streaming formats including: LiveAudio - .LA LiquidAudio - .LQT Streamworks - .MPA Shockwave Audio - .SWA The players for many of these can also play non-streaming audio Most streaming formats deliver mono sound at 8kHz or less

MP3 MPEG Audio Layer-3 In 1987, the IIS started to work on perceptual audio coding in the framework of the EUREKA project EU147, Digital Audio Broadcasting (DAB). In a joint co-operation with the University of Erlangen (Prof. Dieter Seitzer), the IIS finally devised a very powerful algorithm that is standardised as ISO-MPEG Audio Layer-3 (IS 11172-3 and IS 13818-3) MPEG2

MP3 cont 2 By using MPEG audio coding, you may shrink down the original sound data from a CD by a factor of 12, without losing sound quality. Without data reduction, digital audio signals typically consist of 16 bit samples recorded at a sampling rate more than twice the actual audio bandwidth (e.g. 44.1 kHz for Compact Disks). So you end up with more than 1.400 Mb to represent just one second of stereo music in CD quality.

Typical Data Reduction Using MPEG Audio 1:4 MPEG Layer 1 (corresponds with 384 kbps for a stereo signal) 1:6...1:8 MPEG Layer 2 (corresponds with 256 - 192 kbps for a stereo signal) 1:10...1:12 MPEG Layer 3 (corresponds with 128 -112 kbps for a stereo signal) still maintaining the original CD sound quality.

Digitization Sample & Sample Rate

Analog/Digital Conversions A Basic Digital Audio Setup Microphone converts sound into an electrical signal Anti-Alias “Brick Wall” filter removes very high frequencies from signal. ADC periodically measures (samples) the amplitude of the analog signal, sending a stream of numbers to CPU. DAC converts a stream of numbers into a stepped analog signal. Smoothing filter removes staircase shape from signal. Acoustical to Electrical to Digital (numerical) and back

Digitizing Sound Sound is a continuous phenomenon; in the analog studio, it may be represented by a continuous electrical signal. Digital computers can only handle finite, or discrete, information. So we must to convert sound from the analog to the digital domain. This is called sampling. Sample = amplitude of a signal at some instant in time. Samples must be evenly spaced to have any meaning. Sampling Rate = N samples/Second. Standard audio rates are 44.1 KHz for CD, 48 KHz for DAT/ADAT, 96K and 192K for professional digital recording.

Principles of Digitization Why Digitize? Microphones, video cameras produce analog signals (continuous-valued voltages) To store audio or video data into a computer, we must digitize it by converting it into a stream of numbers. Sound as analog signal As I noted before sound is a continuous wave and as all natural phenomena is analog in nature. Microphones detect this analog input, which is nothing but a continuous sequence of voltages. However, in order to store this input in a computer one has to convert it to a digital form, that is into 0s and 1s. Further a continuous wave has infinite resolution which cannot be represented in a computer.

Principles of Digitization Sampling: Divide the horizontal axis (time) into discrete pieces Quantization: Divide the vertical axis (signal strength - voltage) into pieces. For example, 8-bit quantization divides the vertical axis into 256 levels. 16 bit gives you 65536 levels. Lower the quantization, lower the quality of the sound Digitization is achieved by recording or sampling the continuous sound wave at discrete points. The more frequently one samples the closer one gets to capturing the continuity of the wave. Therefore, sampling is the process of dividing the horizontal (time-axis) into discrete points. The other aspect of digitization is the measurement of the voltages at these discrete sampling points. As it turns out these values may be of arbitrary precision, that is we could have values containing small fractions or decimal numbers that take more bits to represent. To cope with this arbitrary precision we use quantization which divides the vertical axis (signal strength or voltage) into discrete points. For example, 8-bit quantization divides the axis into 256 discrete voltage levels. While we are on the topic of quantization, it is important to note that not all quantization is uniform or linear. That is the vertical axis need not always be a linear scale, a non-linear logarithmic scale is used in mu-law encoding.

Common Sampling Rates Which rates can represent the range of frequencies audible by (fresh) ears? Sampling Rate Uses 44.1 kHz (44100) CD, DAT 48 kHz (48000) DAT, DV, DVD-Video 96 kHz (96000) DVD-Audio 22.05 kHz (22050) Old samplers Sound can be sampled as Monaural or Stereo Most software can handle all these rates.

Sampling Considerations Human hearing range not more than 20Hz to 20kHz often only 40Hz to 15kHz in later life Highest frequencies cannot be recorded at 11kHz sampling rate Speech needs 4kHz to 8kHz sampling rate Music needs 22kHz to 44kHz sampling Too high a volume may incur clipping

Digital Audio – Sampling Size The sample size is how much information is recorded at each sampling - also known as Bit Depth The bit depth also influences sound quality An 8 bit sample = 256 values A 16 bit sample can store 65,536 values — A huge difference! 16 bit sampling gives a cleaner waveform with fewer steps

Digital Audio – The Trade-off Mono, 8 bit, 11 kHz audio 1 byte ´ 11,000 ´ 1 second = 11 KB per second 11 KB/s ´ 60 second = 660 KB per minute How much for Stereo and/or 16 bit and/or 44 kHz audio?

Stereo and Mono Mono, 16 bit, 22 kHz audio 2 bytes ´ 22,000 ´ 1 second = 44 KB per second 44 KB/s ´ 60 second = 2.64 MB per minute Stereo, 16 bit, 44 kHz audio 2 bytes ´ 44,100 ´ 1 second ´ 2 = 176 KB per second 176 KB/s ´ 60 second = 10.56 MB per minute

Digital Audio – Compression Many flavours ADPCM – 4:1 MicroSoft, MicroSoft IMA, Creative CCITT – 2:1 A-law and -law Audio MPEG – 20:1

Advantages and Disadvantages Of Compression Smaller disk storage requirements Disadvantages Must be decompressed before use Can take up to twice sound duration Supported by good sound cards and specialist sound editing packages

Common Sample Sizes 8 - 12 bits OK for speech, some games High Fidelity Music: 16 bits minimum CD standard Dynamic range is 96 dB, technically Perfectly adequate for final product Pro Audio: 20 or 24 bits Better for recording, mixing, processing Much better resolution for quiet sounds

What Should You Use? Anything being recorded to CD must be 44.1KHz and 16 bits Not all audio hardware can play at higher rates and greater resolutions To keep things simple and maximize portability, use CD standard for now