Taşoda Ses Tasarım ve Müzik Prodüksiyon

University: İstanbul Technical University pdf download
Institute: Institute of Science and Technology
Programme: Management Engineering
Course: Technology Transfer, R&D and Innovation
Instructor: Prof. Dr. Sıtkı Gözlü

PERFORMANCE CRITERIA CONSIDERATIONS FOR THE DIGITAL MULTITRACK AUDIO RECORDING TECHNOLOGY IN THE MUSIC BUSINESS

Anıl Savaş Kılıç

ABSTRACT

Recording technologies, which came out in the late 1800’s, created a huge recorded-music market in the last century and continue to keep the market still big in the 21st century. With the invention of computers and digital audio recording, the music studio has become a less-complicated place and a less expensive investment today, but still requires an important investment budget in terms of digital recording equipment and software. This study aims to develop performance criteria for the digital multi-track audio recording technology in the music business. A minimum type of recording system configuration is taken as basis in order to achieve a standard set of criteria.

Due to the time limit, research methods below were utilized:
- Literature research.
- Research among interviews made with the industry professionals by one of the most important magazines of the American Music Industry, “the MIX Magazine”.
- Music technology manufacturers’ technical sheets research.
- Deep interviews made with five professionals of the Turkish music industry.

Key words: Performance criteria, digital audio, digital recording, analog-to-digital, recording technologies

I. INTRODUCTION

A Brief History of Sound Recording

It all started in 1877 with Thomas Edison who developed the phonograph that could record the human voice on a tinfoil-wrapped cylinder turned with a hand crank, just before Alexander Graham Bell introduced the graphophone. Bell used cylinders of wax and a motor to turn the cylinder at a steadier rate. Then Edison used paraffin-coated paper and later on coated with gold, so he could make a negative from which other cylinders could be duplicated. In 1891 Emile Berliner invented the gramophone. He used a flat disk instead of a cylinder and the stylus had a back-and-forth motion instead of a hill-and-dale motion. With the invention of vacuum-tube amplifier in 1925, the sound could be amplified prior to recording, which increased the sound quality dramatically. People could listen to shellac records in their living rooms, despite the limited time and the noise of the records. In 1948, vinyl records came out with a 30 minute playing time and a lower noise level. [2]

The true start of progress was the introduction of stereo records in 1956. In 1960s, the three basic media available were: tape, record and FM broadcast, which were all analog. There were developments in both analog audio recording and reproducing after 1960s. Finally, first Pulse Code Modulated (PCM) digital audio technology was demonstrated by NHK (Japan Broadcasting Corporation) in May 1967. It would take ten years to see the first marketed PCM device called PCM-1 by Sony in 1977. [3]

The British Broadcasting Company (BBC) developed an experimental ten-channel digital tape recorder in 1976. Two years later, the 3M Company, working with the BBC, introduced the first commercial 32-track digital recorder. The first computer disk-based random-access sound editor and mixer was developed by the Soundstream company in Salt Lake City, Utah. Their system allowed to mix up to eight tracks or sound files on a computer disk at a time. [4]

Analog systems are still used in the industry and very rarely preferred to digital systems. Most of the studios use 100% digital systems or systems with a structure made of analog and digital compounds. Digital technology also leads to a new studio concept called project studio, which “features an artist working primarily alone from usually home-based production studio doing creative work using the tools of his trade” [1]. A significant percentage of the music production is realized in project studios and delivered to the commercial studios to be finalized.

How Digital Audio Recording Works

The sampling technique is used in digital recording. “Sampling is the process of taking ‘snapshots’ of a signal and transmitting (or storing) the snapshots, rather than dealing with the continuous signal itself. Surprisingly, if we take snapshots at a sufficient rate, we do not lose information about the signal. This means that we can use the interval between snapshots for a variety of useful purposes, without compromising the integrity of the signal itself…[5]”

The advantages of digital recording over analog can be stated as follows: “(1) The quality of reproduction of a well-engineered digital audio system is independent of the medium and depends on the quality of the conversion process. (2) The conversion of audio to the digital domain allows tremendous opportunities which were denied to analog signals [6]” The audio data collected by sampling can be restored in binary numbers so that it can be stored, processed and reproduced by computers and the copies have exactly the same audio quality as the master. However, there are still industry professionals like the world-famous artist Moby preferring analog systems to digital systems [21].

Outline of the Digital Multi-Track Audio Recording System

A basic digital system consists of a microphone which transduces air pressure variations into electrical voltages, a preamplifier which boosts this electrical signal, a low pass anti-aliasing filter which eliminates the high frequencies that cannot be sampled due to capacity of the Analog-to-Digital Converter (ADC), an ADC which converts the voltages into a string of binary numbers at each period of the sample clock and a digital recording medium which stores the binary numbers to record the sound. The system should also utilize a Digital-to-Analog converter which changes the numbers into a series of voltage levels, a low pass smoothing filter which filters the converted digital data into a continuous-time waveform, an amplifier which boosts the electrical voltage and a loudspeaker whose vibration causes air pressure to change, thus create the sound we hear, in order to playback the sound (Figure 1). [4]

If we take the literature and the business practice into consideration, Digital Multi-Track Audio Recording Systems can be classified in three groups by the medium used to store data:

1- Digital Tape Recorders
2- Hard Disk Recorders
3- Optical Digital Recorders

When the systems and equipment put on the market by the manufacturers and the applications of these systems and equipment in the recording studios are examined, two types of Digital Multi-Track Audio Recording Systems stand out:

1- Turnkey Systems
2- User-Configured Systems

Figure 1: Overview of digital recording and playback [4, pp. 23]

Aim of the Paper

The aim of the paper is to guide digital recording technology users to make more accurate decisions on purchasing technology, enabling them not only to consider the technical specifications but also focus on all the aspects of the performance, especially the organizational criteria. In addition, providing a starting point to determine an accurate set of technological performance criteria for the digital multi-track audio recording technology in the music business is another purpose of this study.

Scope of the Paper

According to the two different classifications above, there can be six different types of digital multi-track audio recording systems in theory. The technology performance criteria must be unique for each system; one of these six combinations has to be chosen. Turnkey systems that use hard disks as the recording media are chosen due to the following reasons:

1- Hard disk recorders have a wider range of users in the music business.
2- The performance of each individual element in user-configured systems differs among different configurations.

The outboard and effects equipment are not in the scope of this paper considering standardization of the criteria. The system whose technology performance criteria are studied in this paper consists of;

- a computer
- a software
- a DAC and an ADC

The computer and its operating system are not evaluated while developing the criteria because they can be modified or changed in a constant setup. Most of the recording software employs MIDI sequencing and music notation, editing, mixing, and score printing tools. Thus, these features are also included in the technology performance criteria of the digital multi-track recording systems. Finally, comparison of different manufacturers’ systems, setting the prioritization percentages of each criterion is not in the scope of the paper.

II. THEORETICAL BACKGROUND

Through literature research technical articles on performance analysis, or test approaches of the electronic circuits or modules in the elements (software, hardware or the computer) of the digital multi-track recording systems have been found. There are also manufacturers’ technical specifications sheets of the elements of the digital multi-track recording systems, but there are no articles related to developing technology performance criteria of a digital recording system as a whole.

III. METHODOLOGY

First, a literature research has been done. Articles related with the topic were examined and used to determine the criteria for the digital multi-track audio recording technology in the music business. An initial classification of the criteria has evolved during this research. Secondly, a research through the music technology manufacturers’ technical sheets [9] [10] [11] [12] [13] has been done. The criteria and the classification of the criteria have been updated after this research. As the next step, a research among interviews made by one of the most important magazines of the American Music Industry, “the MIX Magazine” with the industry professionals has been utilized and comments on the topic has been found and evaluated. Finally, the updated criteria table has been presented to the five Turkish music industry professionals who are Alp Turaç, Ayhan Sayıner, Çağlar Türkmen, Mustafa Kemal Öztürk, Dr. Pieter Snapper (in alphabetical order) and their comments were asked. The final criteria table has been formed according to the information gained in these interviews.

The first priority is the criteria’s measuribility by the user, so the low-level technical criteria like “Quantization noise power spectral density when the input to the ADC is the sum of a number of digitally modulated signals [7]”, or “offset voltage”, “gain error”, “differential non-linearity” and “integral non-linearity” [8] are not involved. Instead of these, the audible results are taken as criteria and classified under “Audible Technical Criteria” title.

IV. FINDINGS OF THE STUDY

Grouping of the Criteria

Performance criteria are classified into four groups:

1- Technical Criteria: The criteria related to the technical issues and features.

a. Software and Hardware: The technical criteria for both software and hardware.

b. Software: The technical criteria for software.

c. Hardware: The technical criteria for hardware.

2- Audible Technical Criteria: The criteria that is related to a technical matter but evaluated by listening.

a. Software and Hardware: Audible technical criteria for both software and hardware.

b. Software: Audible technical criteria for software.

c. Hardware: Audible technical criteria for hardware.

3- Software User Friendliness: The criteria for software’s user friendliness.

4- Organizational Criteria: The criteria related to the organizational issues.

Definition of Each Criterion

1- Technical Criteria

a. Software and Hardware

Sampling Rate: Sampling Rate is described as “the rate which samples are taken. The sampling frequency is expressed in terms of samples per second. This is an important specification of digital audio systems…”, “…expressed in terms of Hertz [4]”. This criterion is referred to the supported sampling rate of the converter and the software. The more may not be the better: “I do not use more than 96000 kHz because the sound starts to get deteriorated [18]”.

Bit Rate: The Analog-to-Digital Converter converts the voltages into a string of binary numbers [4]. The numbers are stored in bits. This criterion is referred to the supported bit rate of the converter and the software.

Operating System Compatibility: This criterion is referred to the operating systems that the hardware & software is compatible with.

Third Party Compatibility: This criterion is referred to the compatibility with the third party hardware and/or software.

Monitoring Latency: The amount of time it takes the equipment to carry an audio input, process it and play it back.

b. Software

The Number of Simultaneous Audio Tracks: This criterion is referred to the number of audio tracks that can be used simultaneously while recording and playback.

The Number of Simultaneous MIDI Tracks: This criterion is referred to the number of MIDI tracks that can be used simultaneously while recording and playback.

The Number of Internal Buses: This criterion is referred to the number of buses that can be used in each project.

The Number of Possible Software Instruments: This criterion is referred to the number of software instruments that can be used in each project.

Diversity of Bundle Plug-ins: The functional diversity of plug-ins that come bundle with the software.

Effectiveness of the Bundle Plug-ins: Effectiveness is high if the quality of the bundle plug-ins eliminates to buy the third party plug-ins.

Same Version Compatibility: This criterion is referred to the compatibility with the same version of the software in another recording system. There is an example about the Apple (the manufacturer)’s Logic (the recording system), “Each Logic system is unique; you can not open studio A’s recording session file in studio B directly, even both studio A and studio B has the same version of Logic software. [17]”

Compatibility: This criterion is referred to the compatibility with other software. This is an important criterion for users who have to work in different studios working with different software.

Backward Compatibility: This criterion is referred to the compatibility of older versions with the newer versions of the software.

Processing Power Demand: This criterion is referred to the software's processing power demand on the host.

Hardware Inserts: This criterion is referred to the ability to connect external devices to the system. “I was really influenced by something George Massenburg said: Analog likes to marry with digital. If you record digital, make sure you get some analog processing into the chain and vice versa. [19]” are the words of David Paich, who wrote many of the famous band Toto’s hits, stressing the importance of hardware inserts in a digital recording system.

Meantime Between Failures: This criterion is referred to how frequent the system crashes. The co-producer of Dire Straits’ Mark Knopfler, Chuck Ainlay says, “…we just want to do our work, and that's what's good about it. It doesn't crash and it gives me all the speed and processing possibilities that I could ever want. I can't believe how many plug-ins I can effortlessly run. It's really brought Nuendo into the professional world in my viewpoint. [20]”

Failure Recoverability: This criterion is referred to how successful the system responds to a failure. “After a system crash during recording, the recorded data must be recovered accurately and quickly [18]”. “The lost data doesn’t only mean the loss of budget and time, but the creative work which will probably not be captured in the same way again [15]”.

Bug Rate: This criterion is referred to how mature the software is presented to the market. “Some companies have policies of using the customers as beta testers, so they release their software prematurely. This saves them time for the competition, but there is payback of customer’s confidence loss [15]”.

Delay Compensation Engine: This criterion is referred to the presence of a delay compensation engine. This engine “maintains time-alignment between tracks that have plug-ins with different DSP delays that occur in audio, Auxiliary Input, Master Fader or Instrument Tracks because of plug-in use and mixer routing [10]”.

c. Hardware

The Number of Analog Inputs: This criterion is referred to the number of analog inputs of the converter.

The Number of Analog Outputs: This criterion is referred to the number of analog outputs of the converter.

Jack Types of Analog Inputs: This criterion is referred to the feature of jack inputs (balanced / unbalanced).

The Number of Digital I/O: This criterion is referred to the number of digital I/O that the hardware hosts.

Formats of Digital I/O: This criterion is referred to the types of digital I/O types that the hardware hosts.

Digital Signal Processing (DSP) Power for Plug-ins: This criterion is referred to the processing power of the converter.

Internal Bit Depth: This criterion is referred to the bit depth of internal processing.

I/O Independence: This criterion is referred to the independence of the Digital I/O’s from Analog I/O's. “The independence can be an advantage or a disadvantage according to the user’s needs [17]”.

2- Audible Technical Criteria

a. Hardware

Clock Accuracy (Amount of Jitter): This criterion is referred to the sampling clock accuracy of the system. “Sample clocks, as used in digital audio systems, provide the timing intervals that determine when audio samples are recorded or playback. Jitter is the effect that varies the time base or regularity of the clock pulses provided to the system [9]”.

b. Software

Algorithms for Summing: This criterion is referred to the ability of accurate summing of multiple channels into stereo. “Multiple tracks sound different when listened in different systems [14] [15] [17] [18]”.

Algorithms for Exporting: This criterion is referred to the ability of accurate exporting of multiple channels into stereo. “According to the tests I’ve done with several systems, what is heard during playback is not the same with the exported stereo file. The stereo image gets narrower, there becomes a reduction at high frequencies, and dynamic range gets narrower in the exported file [15]”.

c. Software and Hardware

Recording Quality: This criterion is referred to how the recorded audio sounds. In other words, how accurate the analog sound is converted to digital.

Playback Quality: This criterion is referred to how the stereo (not multiple) audio sounds during playback. “Stereo audio playback quality differs from system to system as well. [15]”

3- Software User Friendliness

Recording: This criterion is referred to the variety of recording functions and their ease of use.

Editing: This criterion is referred to the variety of editing functions and their ease of use.

Mixing: This criterion is referred to the variety of mixing functions and their ease of use.

Automation: This criterion is referred to the variety of automation functions and their ease of use.

MIDI Sequencing: This criterion is referred to the variety of MIDI recording and editing functions and their ease of use.

Flexibility of the Editing Tools: This criterion is referred to the variety of editing tools and editing functional modes.

Music Notation and Score Printing: This criterion is referred to the variety of music notation and score printing functions and their ease of use.

4- Organizational Criteria

Learning Cost: This criterion is referred to the cost in terms of time and money to be an expert operator of the system.

Maintenance Cost: This criterion is referred to the cost in terms of time and money for the maintenance of the system.

Updates Frequency: This criterion is referred to the number of updates released in one year.
Update Reliability: This criterion is referred to the efficiency of the updates. “Sometimes updates can ruin the system instead of fixing it [16]”.

Technical Support Accessibility: This criterion is referred to the accessibility of the technical service.

Technical Support Response Rate: This criterion is referred to the technical service response rate to the problems.

Bug Fixing Time: This criterion is referred to how fast the reported bugs are fixed. “Some manufacturers respond to the bug reports at a higher rate than the others [17]”. “This is because the manufacturers who supply fast-response to the bug reports have a smaller population of customers [16]”

Third Party Software Testing: This criterion is referred to the presence and frequency of the updated third party software tests made by the manufacturer.

Market Dominance: This criterion is referred to how dominant the recording system is in the market. Caglar Türkmen says, “I will have to invest in a Protools system because it’s used in the industry at a high rate, even though it’s not the best choice if how it sounds is considered [15]”.

Forecasted Future: This criterion is referred to which direction the market is going to. For instance, “DSP systems are becoming obsolete and multi core processors will become widespread in the next two or three years [15]”. Another example is a forecast stating that “Apple will dominate the industry with its new policy of pulling the amateur musicians into the market with the Garage Band software [17]”.

VI. DISCUSSION

These criteria provides performance evaluation of the digital multi-track audio recording technology from the user’s point of view. The low-lewel technical performance criteria of the circuits or the modules of the equipment are not involved in this set of criteria because it’s in the scope of the manufacturer’s performance tests. The audible effects of this technical structure’s consequence are in the scope of this study because whatever the low-level technical performance tests expose, the user will decide using the technology according to how it sounds, and the technology will survive if the users appreciate how it sounds.

VII. CONCLUSION

Performance criteria for the digital multi-track audio recording technology in the music business are developed for Turn-Key systems which use hard disks as recording media. The criteria are grouped into four divisions:

1- Technical Criteria: The criteria related to the technical issues and features.

2- Audible Technical Criteria: The criteria that is related to a technical matter but evaluated by listening.

3- Software User Friendliness: The criteria for software’s user friendliness.

4- Organizational Criteria: The criteria related to the organizational issues.

These criteria are developed in order to use a more accurate method while evaluating digital multi-track audio recording systems. Technology investors may focus on one aspect of the technology thus lose sight of the big picture. Using these criteria, they will be able to make reliable decions on investing on digital recording systems.

VIII. LIMITATIONS AND FUTURE RESEARCH

There are limitations of the study. First, a comprehensive survey wasn’t utilized due to time limit. Instead, deep interviews with five professionals in the Turkish music industry and a research through MIX Magazine interviews were done. Second, there are six types of digital recording systems which are stated in the paper, and five of them stayed out of the scope of the paper. Other studies should be done to cover all the possible digital recording systems in order to develop the entire technology performance criteria for the digital multi-track recording systems.

REFERENCES

[1] Fisher J. P., 2001. Profiting From Your Music and Sound Project Studio, Allworth Press, An imprint of Allworth Communications, New York.

[2] Rossing T. D., Moore F. R., Wheeler P. A., 2002. The Science of Sound, 3rd Edition, Pearson Education, Inc., publishing as Addison Wesley, San Francisco.

[3] Baert L., Theunissen L., Vergult G., Maes J., Arts J., 1995. Digital Audio and Compact Disc Technology, 3rd Edition, Focal Press, An Imprint of Butterworth-Heinemann, Oxford.

[4] Roads C., 1998. The Computer Music Tutorial, 3rd printing, The MIT Press, Cambridge, Massachusetts, London.

[5] Kirk R. & Hunt A., 1999. Digital Sound Processing for Music and Multimedia, 1st Edition, Focal Press, An Imprint of Butterworth-Heinemann, Oxford.

[6] Watkinson J., 1994. The Art of Digital Audio, 2nd edition, Focal Press, An Imprint of Butterworth-Heinemann, Oxford.

[7] Kumar R., Taggart D., Goo G., 2004. Performance Analysis of Analog-to-Digital Converters for Wideband Digitally Modulated Signals, IEEE Aerospace Conference Proceedings, pp. 1375-1382.

[8] Ehsanian M., Kaminska B., Arabi K., 1996. A New Digital Test Approach for Analog-to-Digital Converter Testing, 14th VLSI Test Symposium, IEEE, pp. 60-65.

[9] KashiwaG., 2005. Clocking, Jitter and the Digidesign 192 I/O Audio Interface, Technical Whitepaper, Digidesign, a division of Avid Technology.

[10] 2006. Protools Reference Guide Version 7.2, Digidesign, a division of Avid Technology.

[11] 2004. Logic Pro 7 Product Overview, Apple Computer Inc.

[12] 2004. Specification Sheet, Apple Computer Inc.

[13] Bachmann C., Bischoff H., Grossmann B., Pfeifer S., Schomburg C., 2006. Cubase 4 Operation Manual, Steinberg Media Technologies GmbH.

[14] Öztürk, M.K., 2006. Personal interview.

[15] Türkmen, Ç., 2006. Personal interview.

[16] Turaç, A., 2006. Personal interview.

[17] Sayıner, A., 2006. Personal interview.

[18] Snapper, P., 2006. Personal interview.

WWW REFERENCES:

[19] Eskow, G., 2006. David Paich's ATS,
http://mixonline.com/recording/interviews/audio_david_paichs_ats/index.html

[20] Clark, R., 2005. Mark Knopfler,
http://mixonline.com/mag/audio_mark_knopfler/index.html

[21] Jackson, B., 2005. The Many Faces of Moby,
http://mixonline.com/mag/audio_faces_moby/index.html

FIGURES

Figure 1: Overview of digital recording and playback