1. Demystifying Digital Audio + Effective Demonstration of High Definition Audio Johan Coorg

2. Introduction

3. Introduction - History To understand best practices for proper demonstration of high definition digital audio, we must first be familiar with audio formats and their history. Everybody more or less understands video; the higher the number, the more pixels resulting in better picture quality… 480, 720, 1080, 1920 (“full HD”) and now Ultra HD video known as “4K” is coming. Further reading… http://en.wikipedia.org/wiki/Video_resolution Page 3

4. Introduction - History The story with digital audio formats and resolution is not so simple and it is less obvious to understand. An interesting timeline of all audio formats history can be found at… http://en.wikipedia.org/wiki/Timeline_of_audio_forma tshttp://en.wikipedia.org/wiki/Timeline_of_audio_forma ts When considering digital audio, the story becomes pretty complicated... http://en.wikipedia.org/wiki/Audio_file_format Page 4

5. Digital Audio Formats and their Implications Defined

6. Demystifying Digital Audio - first steps When explaining digital audio to a non expert, it is important to have a basic understanding of the background, and to perhaps highlight, the most common terms which most will have heard of. 1- CD Audio (The Red Book Standard) 2- MP3 (lossy compression) 3- FLAC (lossless compression) 4- WAV Page 6

7. 1- CD audio, the Red Book Standard The “Red Book Standard”, specifying the physical properties of a CD was agreed in 1980 through collaboration between Philips and Sony. First made commercially available in 1982 A CD can hold up to 80 minutes of audio or 700 MB of data. Recording sampling rate from analog is 44.1KHz (44,100 times per second) Bit depth on a CD is 16 (the number of bits recorded for each sample). This affects dynamic range capability. 16 bit has a maximum dynamic range of 96 dB. This is referred to as resolution. CD Audio is often known as full resolution – but this is not true. It is a question of “slicing up” chunks of analogue information into 1s and 0s to achieve 80 minutes of audio at 16 bit resolution. Sales of CDs are plummeting in favour of downloading of files to play from computer / media players. Page 7

8. 1- CD audio, cont’d Ripping is the process of copying audio or video content to hard disk files, typically from media such as CD or DVD. Digital Audio Extraction (DAE) is a more formal phrase applied to the ripping of CDs. Ripping is distinct from simple file copying, in that the source audio/video is not originally formatted for ease of use in a computer file system. Ripping such data (as present on a CD), using CD ripping software, usually involves reformatting it and optionally compressing it during the extraction process. Further reading: http://en.wikipedia.org/wiki/CD_audio#Audio_CD http://en.wikipedia.org/wiki/Ripping Page 8

9. 2- MP3 MP3 is perhaps the most common format used for encoding digital audio onto a file, using a form of lossy data compression, designed to greatly reduce the amount of data required to represent the audio recording and still sound like a “faithful reproduction” of the original uncompressed audio for most listeners. When performing lossy audio encoding, such as creating an MP3 file, there is a trade-off between the amount of space used and the sound quality of the result. An MP3 file saves file size and download time, but when it is created using the mostly widely used setting of 128 Kbps, will result in a file which is about 1/11 the size of the CD file. In comparison it will sound poor- as if some of the music is missing. An MP3 file can also be constructed at lower or higher bit rates, resulting in lower or higher sound quality. Publically released in 1994. Further reading - http://en.wikipedia.org/wiki/Mp3http://en.wikipedia.org/wiki/Mp3 Page 9

10. 3- FLAC A codec (coder-decoder) which allows digital audio to be losslessly compressed to a file readable by a computer, such that file size is reduced without any information being lost. Digital audio compressed using the FLAC algorithm can be reduced to 50%-60% of file original size and decompressed into an identical copy of the original audio data. It works rather like Zip and Unzip, but specifically for audio with more efficient compression. Zipping an audio file will compress by 10%-20% and not be playable directly using media software. FLAC (unlike WinZip) works “on the fly”. Released in 2000. Further reading - http://en.wikipedia.org/wiki/FLAChttp://en.wikipedia.org/wiki/FLAC Page 10

11. 4- WAV Waveform Audio File Format (WAVE, or more commonly known as WAV due to its filename extension), is a Microsoft and IBM audio file format standard for storing audio bitstreams on PCs. It is an application of the Resource Interchange File Format (RIFF) bitstream format method for storing data in “chunks”. It is compatible with Windows, Macintosh and Linux systems and similar to the Audio Interchange File Format (AIFF) developed by Macintosh. WAV bitstream files are encoded using the Linear Pulse Code Modulation (LPCM) They are usually files using no compression of the original. Further reading: http://en.wikipedia.org/wiki/WAVhttp://en.wikipedia.org/wiki/WAV Page 11

12. High Definition Audio- Size Matters MP3 is utilised to store more audio content on a given hard drive- but at the price of audio quality. It is easily discernable as poor sound on good audio equipment. Resolution is often hugely worse than CD (in itself compromised to fit 80 minutes of audio material onto a 120mm disc). Now that storage space is vastly larger and cheaper, we no longer have to compromise. The world of “Studio Master” resolution downloads is fast growing, with an ever increasing catalogue available. Studio Master files are encoded at 24-bit depth resolution or higher, and currently at sampling rates up to 192kHz. This is so close to analogue quality that it is virtually impossible for the human ear to perceive any difference. Page 12

13. File Size Comparisons- putting it all into perspective. 17:05 of music – Beethoven Piano Concerto No 3 in C minor Op 37, Allegro con brio MP3 @ 128KBps - 16,025 KB CD Audio quality @ 44.1KHz, 16 bit - 176,658 KB or 64,020 KB using FLAC Studio Master Audio quality @ 96KHz, 24 bit - 576,676 KB or 313,240 KB using FLAC Studio Master Audio quality @192KHz, 24 bit -1,182,197 KB or 642,148 KB using FLAC Page 13 The highest resolution file takes up almost the twice capacity of a whole CD without using FLAC! The highest resolution file is sampled at over 4 times CD. 24 bit resolution means a practical dynamic range of 124dB instead of 96dB

14. Correct Playback and Demonstration of High Definition Audio using Computer As Source

15. Items to take care of using Computer as Source. Use good software for combination of ease of use, good visual display and file playback performance capabilities. Check your USB audio driver capability. As in a standard hifi system, try to use quality cables. A high quality USB cable makes a huge difference! http://www.audioquest.com/usb-digital- audio/diamondhttp://www.audioquest.com/usb-digital- audio/diamond As in a standard hifi system, choose demonstration material carefully. Page 15

16. Best Software for PC – J River Intuitive, great UI, versatile, highly configurable. Page 16

17. Best Software for MAC – Amarra By default attaches itself as an iTunes plug-in. Page 17

18. USB audio driver USB Audio Class 1 was the first USB Audio Class supported by Windows. By creating a device which conforms to the Windows Driver Model, it is possible to transmit audio data at rates of up to 24- bit/96kHz sample frequency over USB. Present on MACs earlier than OSX10.5 USB Audio Class 2 is a more recent introduction allowing transmission of higher data rates over USB. The maximum data rate supported by USB Audio Class 2 is double that of Class 1 at 24- bit/192kHz. Modern MACs have Class 2 whereas PCs by default come with Class 1. Page 18

19. ASIO Audio Stream Input/Output (ASIO) is a computer sound card driver protocol for digital audio, providing a low-latency high fidelity interface between a software application and a computer’s soundcard. It is advisable to download ASIO driver for PC to improve Windows audio file streaming performance. www.asio4all.com www.asio4all.com MAC audio architecture is superior providing a more bit perfect audio stream from the soundcard. Therefore ASIO driver not needed. Page 19

20. X300A demonstration All the information so far is pertinent to best effective demo of X300A- not just any old computer speaker, but a fully blown and easy to use high resolution hifi system for your computer. Remember the built in DACs are 96KHz / 24 bit capable and will downsample correctly streamed 192KHz / 24bit material from USB output of computer. Page 20

21. LS50 demonstration Remember the LS50, despite its size, is a high resolution monitor passive speaker which will benefit by demonstrating “studio master” resolution high definition audio files using computer as source, feeding a high quality DAC connected to a quality amplifier. Page 21

22. Any further questions? I will be happy to help Johan.coorg@kef.comJohan.coorg@kef.com