Yamaha THX pm3 User Manual

M2TB rev. 3.5.2

Multichannel Monitoring Tutorial Booklet

2nd Edition

With Reference to

and

the surround monitoring functions of the

Yamaha DM2000, DM1000, and 02R96 digital consoles

May 2005

rev. 3.5.2

Multichannel Monitoring Tutorial Booklet (M2TB) rev. 3.5.2

Masataka Nakahara : SONA Corporation

Multichannel Monitoring Tutorial Booklet

Second edition, rev. 3.5.2., May 2005

(First edition, rev. 230, June 2002)

Contents

Foreword ......................................................................................................................................................3

Preface .......................................................................................................................................................... 4

0. Introduction ............................................................................................................................................. 5

1. What is surround? .................................................................................................................................. 6

1-1. Stereo and surround ..................................................................................................... 6

1-2. Channel configuration ................................................................................................. 6

1-3. Key points for multi-channel monitoring ................................................................... 8

2. Multi-channel formats............................................................................................................................ 9

2-1. Surround processing methods.................................................................................... 17

2-2. Encoding and compression methods......................................................................... 19

2-3. Recording response .................................................................................................... 22

2-4. Playback response ...................................................................................................... 23

2-5. Down-mixing ............................................................................................................. 29

3. Playback environment.......................................................................................................................... 32

3-1. Rec. ITU-R BS. 775-1 ...............................................................................................32

3-2. L, R ............................................................................................................................. 35

3-3. LS, RS ........................................................................................................................ 36

3-4. C.................................................................................................................................. 40

3-5. Playback image compatibility with the playback environment ............................... 41

3-6. SUB ............................................................................................................................42

3-7. Monitoring distance ...................................................................................................43

3-8. Monitor alignment ..................................................................................................... 45

3-9. THX

4. Bass management.................................................................................................................................. 50

4-1. Acoustical treatment of the room ..............................................................................50

4-2. Speaker placement ..................................................................................................... 50

4-3. Electro-acoustic methods........................................................................................... 50

4-4. Monitoring the decoder output .................................................................................. 57

5. Monitor systems .................................................................................................................................... 59

5-1. Monitor matrix ...........................................................................................................60

5-2. Bass management....................................................................................................... 60

5-3. Monitor alignment ..................................................................................................... 60

6. Measurement and adjustment............................................................................................................. 61

6-1. Test signal .................................................................................................................. 61

6-2. Main channel level balance .......................................................................................62

6-3. Narrow-band pink noise ............................................................................................ 65

6-4. LFE channel level balance......................................................................................... 67

6-5. Delay adjustments...................................................................................................... 69

7. Summary................................................................................................................................................ 71

Reference materials .................................................................................................................................. 72

pm3TM Certified Studios............................................................................... 48

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Foreword

Surround sound has evolved into more than the experience heard in cinemas. Through the introduction of the DVD, it has invaded most every aspect of our lives — our homes, our cars, and even our workplaces. We n ow l is te n to multi-channel audio delivered via television programs, video games, and even by the music of our favorite bands. With the introduction of the DM2000, DM1000, and O2R96 Digital Consoles, Yamaha provides a platform that includes complete surround sound mixing and monitoring capabilities for studios of all types. These consoles offer a vast array of features and functions that enable the user to create a world of multi-channel content.

Masataka Nakahara (the celebrated acoustician/studio designer and the author of this booklet) and SONA Corporation have designed and supported numerous THX representatives in Japan, they continually inform and educate studios owners in the calibration and design of studio playback systems. During the development of these consoles, Mr. Nakahara offered his years of experience to assist in the design of the surround monitoring capabilities. In conjunction with THX engineers, the release of the Version2 software expands their features even further. This THX pm3 Approved revision includes the addition of THX presets for film, DVD, and music mixing. These are the same settings used in THX certified studios.

Studios have a long track record in mixing mono and stereo content, but for some industry professionals, multi-channel mixing is relatively new. There are more channels, more equipment, and more techniques to be learned. How do you set up your studio? Do I use bass management? There are many questions to be answered. This booklet offers an excellent compilation of the knowledge required to construct a properly configured surround playback environment. Much of this document shares the same principles as THX pm3 program. We are proud of our association with Yamaha, Mr. Nakahara, and SONA Corporation and their efforts to create a manual to help guide the user. It is my sincere wish that engineers carefully read this guidebook in order to obtain an accurate understanding of the surround monitoring functionality provided by the Yamaha digital consoles. Here are the tools. Now, it's up to you to create the perfect mix.

pm3 Certified Studios. As the THX pm3

Steven P. Martz

THX Ltd.

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Preface

As one whose profession is the acoustical design of studios, I place great value on the parting ceremony of handing over to its new owner my creation (studio) whose playback environment and acoustical response I have ensured.

In order to actualize these characteristics in a multichannel studio, it is necessary to collect the fragmentary technical information provided by various standards organizations and manufacturers, and then to organize and understand this information. Doing so takes an enormous amount of time, but one of the most valuable things I gained from the process has been friendships with many superb professionals in the field, including Mr. Steven Martz from THX. As the lessons I learned from them began to take root in me, I have been acquiring valuable new strategies and techniques for studio design.

Initially, I had doubts regarding techniques that seemed at first glance to conflict with a professional approach, such as bass management and diffused surround, but as I spent time with professionals of multi-channel audio, I came to see why many top-ranked experts with far more experience than myself held these opinions and requirements for surround studios. In the process, I gradually obtained a glimpse of various problems and aspects of surround playback that lie behind such questions.

This publication is a valuable booklet that brings together much valuable information obtained from firstrate professionals such as Steven from THX. I consider myself to have been a “ghost-writer” for these experts, and think of them as the real authors of this booklet. I would like to take this opportunity to extend my thanks to each of them.

In view of these intentions, portions of this booklet dealing with various standards have been written so as to list the various multichannel formats as broadly, fairly, and accurately as possible. I beg the indulgence of the reader for allowing me to include material that represents my own opinion as an acoustic designer.

In my opinion, user experience as a listener is of great value in the production process. In order for this to be so, a space for hearing multichannel audio in a correct playback environment is a requirement not only for commercial applications but also for personal applications. This is a case of “one hearing is better than a hundred views.” It is my hope that this booklet will be a step toward obtaining the “hundred views” that will give you the confidence to construct your own multichannel playback environment.

Masataka Nakahara, author

SONA Corporation

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0. Introduction

The most important consideration for a studio monitoring environment is that “the response of all channels be consistent.” The second most important consideration is that this consistent response be “good response.” We c ou l d list numerous parameters for deciding whether the response is “good,” ranging from subjective to physical, but the key point is that there be no large peaks or dips in the frequency response.

In the case of two-channel, it is fairly easy to create an environment in which “the response of all channels — i.e., L and R — is consistent.” We simply need to ensure that the shape of the room and the placement of the speakers is symmetrical between left and right. In the case of multi-channel, on the other hand, it is often difficult to obtain a consistent playback response for all channels simply by creating a symmetrical speaker placement and room shape.

Mixing of the final product must be done in a properly configured playback environment. No matter how high the grade of your equipment, it is impossible to create a final mix unless you have a good-sounding playback environment.

The essential identity of a professional studio is in its good monitoring environment.

The arrival of multi-channel is a good opportunity for us to reconsider the question of “what is a studio monitoring environment?”

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1. What is surround?

1-1. Stereo and surround

“Multi-channel” is sometimes called “surround,” and “two-channel” is often called “stereo.” The precise terms are as follows.

Correct term two-channel stereophonic Abbreviation two-channel Common term stereo

Correct term multi-channel stereophonic Abbreviation multi-channel Common term surround

“Stereo (-phonic) = spatial acoustics”

1-2. Channel configuration

At present, a variety of channel assignments have been proposed for various types of media. The most popular of these are shown below.

3-1ch

2ch

LFE

(SUB)

5.1ch

LFE

(SUB)

(BSl) (BSr)

[Fig. 1] 2ch, 3-1ch, 5.1ch, 6.1ch

6.1ch

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1-2-1. 3-1 ch

This method is based on a two-channel system (L, R), and adds a center channel (C) and surround channel (S). Although there are two surround speakers, one each at left and right, the playback is monaural. The “3” in “3-1” indicates L, C, and R, and the “–1” indicates S. Note that if “3-1” is expressed as “3.1,” this means “L, C, R” + “LFE” .

1-2-2. 5.1 ch

This method is based on the 3-1 ch system, but changes the surround to stereo (LS, RS) and adds an LFE (Low Frequency Effect) channel for low-frequency effects. The LFE channel is played back through a dedicated subwoofer designed for low-frequency playback.

1-2-3. 6.1 ch

This method is based on the 5.1 ch system, and adds a new back-surround channel (BS). If two speakers are provided to play back the back-surround channel, these are sometimes called BSl and BSr, but the signal that is played back is a monaural signal where BSl = BSr.

1-2-4. Other

As other formats, there is 3-2 (without LFE) and 2-2 (without C and LFE), which are based on 5.1ch but do not use specific channel(s) of them As a format with a greater number of channels than 6.1ch, we have 7.1ch.

7.1ch can be subdivided into the SDDS format which is used in film, and Dolby ProLogic IIx which is used in DVD-Video etc. SDDS is a discrete 7.1ch format which adds LC and RC channels between L and C and between R and C respectively, and is used in applications such as supplementing the center gap between screen speakers in large movie theaters. Since the 7.1ch SDDS format is compatible with 5.1ch, we can say that SDDS supports both 5.1ch and 7.1ch configurations. Dolby ProLogic IIx uses matrix logic processing within the decoder to stereoize BS (BSl, BSr), and at present is targeted for surround processing in the playback system of consumer decoders (receivers).

Current multi-channel systems were developed to maintain compatibility with previous systems, and have not been researched or developed in order to reproduce a 360° virtual acoustic space. This means that if you expect current multi-channel systems to deliver full virtual acoustic playback capability, you will be at your wits end. In particular, sound images directly to the side (the phantom sound image of L and LS, or the phantom sound image of R and RS) are difficult to portray with current speaker configurations, due to the physiology of hearing. The key to multi-channel production is how to make effective use of the newly-obtained channels to create a product with the maximum “entertainment value.”

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1-3. Key points for multi-channel monitoring

In our consideration of multi-channel monitoring, it is important to understand the following three key points.

Multichannel

formats

Playback

environment

Bass

management

[Fig. 2] Three keys of multichannel monitoring

In addition to the above three points, this document will discuss the construction of a monitor system, and the measurements and adjustments that are necessary in order to create a multi-channel playback environment.

It should be noted that this booklet is written for medium-to-small multichannel studios, and that much of the material (e.g., speaker placement, delay adjustment, bass management) will not apply to surround monitoring in a large space, such as in a movie theater or in a dubbing studio where the final mix of a film is being made.

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2. Multi-channel formats

At present, multi-channel playback is supported by numerous types of consumer media, of which DVD is one. The playback response for each of these types of media is defined by the organizations or manufacturers listed below.

Media

Playback response

specification

Film SMPTE

DVD-Video

Dolby lab., DTS

DVD-Audio DVD Forum WG4

Super Audio CD

Digital broadcast

Sony, Philips DST coded DSD

ARIB

Dolby lab. Dolby DIGITAL

DTS DTS

Administrative body MPEG-2

Storage method used (Note)

Dolby DIGITAL, DTS, SDDS,

and others

Dolby DIGITAL, DTS, and

others

LPCM, PPCM

(Packed PCM, MLP)

MPEG-2 AAC

<< SMPTE, ISO

<< DVD Forum WG1

=DVD Forum WG4

=Sony, Phillips

<ISO, IEC

–-

<ISO, IEC

Media standards

Other matrix methods*9 such as Dolby Surround, Dolby ProLogic II(x), and Circle Surround

GAME Dolby lab., DTS Dolby, DTS <<

manufacturers

(Notes) “<<” Within the recording format specified by the standards organization, the actual

recording method and playback response are provided by another party.

“<” The recording method specified by the standards organization is used, and the

applying organization considers the playback response.

“=” The standards organization directly specifies the recording method and the playback

response.

DVD-Video also allows LPCM multichannel recording.

The PPCM algorithm is provided by Meridian Audio Ltd.

*3 For PPCM, maximum 96 kHz/24-bit/6ch.

For LPCM, maximum 96 kHz/24-bit/4ch, 96 kHz/20-bit/5ch, 96 kHz/16-bit/6ch. (For 2ch, maximum is 192 kHz/24-bit)

(For 2ch, Plain DSD (uncompressed DSD) is also possible)

Japan

Europe, USA and Korea

Europe, etc.

Can also be applied to analog broadcast.

Indicates that this is not a broadcast media standard, but a recording format standard.

organization

Hardware

[Table 1] Multi-channel formats and standards organizations

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Each format of multi-channel media is characterized by a combination of “surround processing method,” “encoding and compression method,” “recording response,” and “playback response.” Most of these types of media provide “downmixing” functionality to allow two-channel playback.

Multichannel media

Surround

processing

A/D and D/A, Compression

Record

specification

Down

mixing

Playback

[Fig. 3] Factors that feature multichannel media

Currently, the following major multi-channel formats exist as mass consumer media.

Media Video cassette tape, etc.

Method 3-1 matrix 5.0 matrix

Name Dolby Surround

DTS Stereo

Dolby Pro Logic II

Manufacturer, Organization Dolby lab. DTSDolby lab.

Surround processing method 4-2 Matrix Encode 5-2 Matrix Encode

Compression method -- -

L, C, R: full range

LS, RS: 100Hz - 20kHz

Level: L=C=R=LS=RS

LFE: none

Recording response (media)

Playback response (speaker, amp)

L, C, R: full range

S: 100Hz - 7kHz

Level:

L=C=R=S(LS+RS)

LFE: none or added to L/R ( < 120Hz)

L, C, R: full range L, C, R, LS, RS: full range

S: 100Hz - 7kHz

LFE: none

[Table 2-1] Multi-channel formats (typical examples), Video cassette tape etc.

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Media Film

Method 3-1 matrix

Name Dolby Stereo DTS Stereo

Manufacturer, Organization

Surround processing method

Compression method

Recording response (media)

Dolby lab. DTS

4-2 Matrix Encode

L, C, R: full range

S: 100Hz - 7kHz

Playback response (speaker, amp)

Method 5.1 discrete

Name Dolby DIGITAL DTS SDDS

Manufacturer, Organization

Surround processing method

Compression method

Recording response (media)

Playback response (speaker, amp)

Level: L=C=R=S(LS+RS)

L, C, R: full range

S: 100Hz - 7kHz

Dolby lab. DTS Sony

-- -

Dolby AC-3 APT-X100 ATRAC

L, C, R, LS, RS: full range L, C, R: full range L, C, R, LS, RS: full range

LFE : < 120Hz LS, RS: 80Hz - 20kHz *

LFE: < 80Hz

* LS & RS information below 80Hz is summed into the LFE channel during the encoding process.

Level: L=C=R

LS=RS=-3dB

LFE=+10dB in-band gain

LFE: <120Hz (SMPTE standard)*

* Full-band is theoretically possible.

L, C, R, LS, RS: full range L, C, R: full range L, C, R: full range

LFE: 20Hz - 120Hz LS, RS: 80Hz - 20kHz LFE: 20Hz - 120Hz

LFE: 20Hz - 80Hz

Remarks Also possible are 7.1ch (8 ch),

which adds the two channels

LC (between L and C) and RC

(between R and C).

[Table 2-2] Multi-channel formats (typical examples), Film

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Method 6.1 matrix

Name Dolby DIGITAL Surround EX DTS-ES Matrix

Manufacturer, Organization Dolby lab. DTS

Surround processing method LS, RS: 3-2 Matrix encode LS, RS: 3-2 Matrix encode

Compression method Dolby AC-3 (L, C, R, LFE) APT-X100

Surround back channel-

Encode (LS, RS)

L, C, R, LS, RS, BS: full range L, C, R: full range

Recording response (media)

LFE: < 120Hz LS, RS, BS: 80Hz - 20kHz*

LFE: < 80Hz

* LS, RS and BS information

below 80Hz is summed into the LFE channel during the encoding process.

Playback response (speaker, amp)

Level: L=C=R

LS=RS=BS=-3dB

LFE=+10dB in-band gain

L, C, R, LS, RS, BS: full range L, C, R: full range

LFE: 20Hz - 120Hz LS, RS, BS: 80Hz - 20kHz

LFE: 20Hz - 80Hz

[Table 2-2 (continued from preceding page)] Multi-channel formats (typical examples), Film

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Media DVD-Video

Method 3-1 matrix 3-1 discrete

Name Dolby Surround Dolby DIGITAL

Manufacturer, Organization Dolby lab. Dolby lab.

Surround processing method

Compression method -Dolby AC-3

4-2 Matrix Encode -

Recording response (media)

Playback response (speaker, amp)

Method 5.0 matrix 5.1 discrete

Name Dolby Pro Logic II Dolby DIGITAL DTS

Manufacturer, Organization Dolby lab. Dolby lab. DTS

Surround processing method 5-2 Matrix Encode - -

Compression method -Dolby AC-3 DTS Coherent Acoustic Recording response

(media)

Playback response (speaker, amp)

Method 6.1 matrix 6.1 discrete

L, C, R: full range L, C, R, S : full range

S: 100Hz - 7kHz

Level: L=C=R=S(LS+RS) Level: L=C=R=S(LS+RS)

L, C, R: full range L, C, R, S(LS+RS): full range

S(LS+RS): 100Hz–7kHz

L, C, R: full range

LS, RS: 100Hz - 20kHz

LFE: none or added to L/R (<120Hz)

Level: L=C=R=LS=RS

LFE: none

L, C, R, LS, RS: full range

LFE: none

L, C, R, LS, RS: full range

LFE: < 120Hz

Level: L=C=R=LS=RS

LFE=+10dB in-band gain

L, C, R, LS, RS: full range

LFE: 20Hz - 120Hz

Name Dolby DIGITAL Surround EX DTS-ES Matrix DTS-ES Discrete

Manufacturer, Organization Dolby lab. DTS DTS

Surround processing method LS, RS: 3-2 Matrix encode LS, RS: 3-2 Matrix encode -

Compression method Dolby AC-3 (L, C, R, LFE) DTS Coherent Acoustic DTS Coherent Acoustic

Surround back channel-

Encode (LS, RS)

Recording response (media)

Playback response (speaker, amp)

[Table 2-3] Multi-channel formats (typical examples), DVD-Video

L, C, R, LS, RS, BS: full range

LFE: < 120Hz

Level: L=C=R=LS=RS

LFE=+10dB in-band gain

L, C, R, LS, RS: full range

LFE: 20Hz - 120Hz

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Media Music

Method 5.1 (6 ch) discrete

Name DVD-Audio Super Audio CD

Manufacturer, Organization DVD Forum WG-4 Sony, Phillips

Surround processing method --

Compression method

PPCM (Packed PCM, MLP)

DST (Direct Stream Transfer)

Max 96kHz/24bit/6ch

LCPM (uncompressed)

Max 96kHz/24bit/4ch Max 96kHz/20bit/5ch Max 96kHz/16bit/6ch

Recording response (media) L, C, R, LS, RS: full range

LFE: full range

Playback response (speaker, amp)

Other methods

Level: L=C=R=LS=RS=LFE

L, C, R, LS, RS: full range

LFE: Not prescribed

(full-range is possible)

2-1, 2-1.1, 3, 3.1, 3-1, 3-1.1,

3, 3.1, 2-2, 2-2.1, 3-2

2-2, 2-2.1, 3-2 etc.

[Table 2-4] Multi-channel formats (typical examples), Music

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Media Digital broadcast

Method 5.1 discrete

Main countries Japan Europe, etc.

Name --

Manufacturer, Organization Signal format: ISO, IEC

Playback response, etc.: ARIB

Signal format: ISO, IEC

Playback response, etc.: Each

administrative body

Surround processing method --

Compression method MPEG-2 AACMPEG-2

Recording response (media) L, C, R, LS, RS, LFE*: full range L, C, R, LS, RS: full range

LFE: < 125Hz

Playback response (speaker, amp)

Level: L=C=R=LS=RS Level: L=C=R=LS=RS

LFE: Prescribed by ARIB LFE: Prescribed by administrative body

L, C, R, LS, RS: full range L, C, R, LS, RS: full range

LFE: Prescribed by ARIB LFE: 20 - 125 Hz

Main countries Europe, USA, Korea, etc. Europe, etc.

Name Dolby DIGITAL DTS

Manufacturer, Organization Dolby lab. DTS

Surround processing method --

Compression method Dolby AC-3 DTS Coherent Acoustic

Recording response (media)

L, C, R, LS, RS: full range

LFE:

< 120Hz

Level: L=C=R=LS=RS

Playback response

(speaker, amp)

LFE=+10dB in-band gain

L, C, R, LS, RS: full range

LFE: 20Hz - 120Hz

Other methods

Matrix methods: Dolby Surround, ProLogic II(x), Circle Surround, etc.

Discrete methods: 3-1, 5.0, etc.

*In MPEG-2 AAC, the LFE channel supports full-band encoding, but a bandwidth limitation may be

applied in transmission.

[Table 2-5] Multi-channel formats (typical examples), Digital broadcast

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Media Games

Method 5.1 discrete 5.0 matrix

Name Dolby DIGITAL DTS Dolby Pro Logic II Manufacturer,

Organization Surround processing method Compression method

Recording response (media)

L, C, R, LS, RS: full range L, C, R: full range

Dolby lab. DTSDolby lab.

––5-2 Matrix Encode

Dolby AC-3

DTS Coherent

Acoustic

–

LFE: < 120Hz LS, RS: 100Hz - 20kHz

LFE: none or added to

L/R (<120Hz)

Playback response (speaker, amp)

Level: L=C=R=LS=RS, Level: L=C=R=LS=RS,

LFE=+10dB in-band gain LFE: none

L, C, R, LS, RS: full range L, C, R, LS, RS: full range

LFE: 20 - 120Hz

Other methods Interactive, etc.

[Table 2-6] Multi-channel formats (typical examples), Games

LFE: none

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2-1. Surround processing methods

There are two types of surround processing method; “matrix” and “discrete.”

2-1-1. Matrix

This method uses phase synthesis technology to record a larger number of channels on a limited number of tracks. This means that for some channels, there may be restrictions in playback bandwidth and channel separation (crosstalk). Matrix processing is often used for analog recording where the number of tracks is limited, such as for the analog tracks of a film, or on video cassette tape. However in principle, it could also be applied to digital media such as CD. Recently, 5.0 matrix formats using Dolby Pro Logic II have been used frequently in game media.

Production

L R

C S

Master

Surround processing

[Fig. 4] 3-1Matrix

Production

L R

(LFE)

LS RS

Master

Playback by end-users

Lt (L total)

Rt (R total)

Media

Surround processing

Movie, VHS etc.

Playback by end-users

Lt (L total)

Rt (R total)

Media

R C’(≒in-phase signal of Lt and Rt) S’(≒anti-phase signal of Lt and Rt)

L (+LFE)

R (+LFE) C’

LS’ RS’

Surround processing

Game etc.

[Fig. 5] 5.0 matrix

If the master source of the LFE channel contains the important information and it needs to be played back, it should be mixed into L&R in advance.

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Production

L R

LFE

LS RS BS

Master

Surround processing

Playback by end-users

L R C

LFE

LSt

RSt

Media

Surround processing

Movie, DVD-Video etc.

LFE

BS’(

in-phase signal of LSt and RSt)

≒

[Fig. 6] 6.1 matrix

2-1-2. Discrete

This method allows each channel to be recorded as a completely independent track. This became possible with the advent of high-capacity media such as DVD, and with the advance of digital compression technology.

Production

L R C

Master

Surround processing

DVD-Video, DVD-Audio, DTV etc.

Playback by end-users

L R C S

Media

Surround processing

L R C

[Fig. 7] 3-1Discrete

Production

L R C

LFE

Master

Surround processing

Movie, DVD-Video, DVD-Audio, Super Audio CD, DTV, GAME etc.

Playback by end-users

L R C

LFE

LS RS

Media

Surround processing

LFE

L R C

[Fig. 8] 5-1 Discrete

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Production

L C R

LFE

LS RS BS

Master

Surround processing

Playback by end-users

L C R

LFE

LS RS BS

Media

Surround processing

DVD-Video

L C R

LFE

LS RS BS

[Fig. 9] 6.1 Discrete

2-2. Encoding and compression methods

2-2-1. Encoding methods

When encoding an analog signal into a digital signal, the encoding performance is largely dependent on two parameters; the sampling frequency (fs[Hz]) which corresponds to the sampling precision of the time axis (frequency axis), and the number of bits used for quantization (Qb[bit]) which corresponds to the sampling precision of the amplitude (loudness). For both fs[Hz] and Qb[bit], higher values allow the occurrence of digital encoding noise to be minimized. This means that for both fs[Hz] and Qb[bit], higher values are generally interpreted as “higher audio quality.” In two-channel media, a CD is encoded at fs=44.1 kHz/Qb=16 bit, and DAT is encoded at fs=48 kHz/Qb=16 bit. The dynamic range for these types of media is approximately 96 dB. In multimedia, DVD-Audi o is encoded with six channels of fs=96 kHz/Qb=24 bit, giving a dynamic range of approximately 144 dB. This type of encoding is known as multi-bit encoding; the upper limit of the frequencies that can be reproduced is determined by fs/2, and Qb essentially determines the dynamic range. In contrast, the single-bit high-speed sampling method uses the minimum number of quantization bits — Qb= 1bit — and instead samples at an extremely high sampling frequency. In the Super Audio CD (SACD) developed by Sony and Phillips, this is called the DSD (Direct Stream Digital) method. Because single-bit high-speed sampling expresses the amplitude of the sound not as a stepwise amplitude of Qb but rather by the density of the sound pressure. It is said that this encoding method is closer to the physical characteristics of the sound wave itself. However since Qb=1 bit, the quantization noise when encoding is much greater than with multi-bit methods and an extremely high sampling frequency is required in order to remedy this. The Super Audio CD uses a very high sampling frequency of 2.8224 MHz with Delta-Sigma conversion, shifting (noise shaping) quantization noise outside the audible range, and delivering better than approximately 120 dB of dynamic range in the audible range. The recording bandwidth is said to be DC through 100 kHz. In this way, there are currently two ways to digitally encode an audio signal; “multi-bit methods” and “single-bit high-speed sampling methods.” Generally, “PCM” or “LPCM” indicate “multi-bit methods.” In contrast, since the Super Audio CD is currently the only mass-market media that uses single-bit highspeed sampling, single-bit high-speed sampling and DSD are often used as synonyms.

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2-2-2. Compression methods

Compression methods can be broadly divided into two types; lossy compression and lossless compression. With lossy compression, the original signal cannot be recovered in its entirety from the compressed signal that is recorded; i.e., this is irreversible compression. This method generally takes advantage of psychoacoustic phenomena to lower the redundancy of the original signal, thus compressing it. Lossless compression allows the original signal to be completely recovered from the compressed signal that is recorded; i.e., this is reversible compression. This method is used to compress files on a computer. It uses mathematical means to lower the redundancy of the original signal, compressing it. Thus, lossless compression delivers a lower compression ratio than lossy compression.

Examples of lossy Method Dolby AC-3, DTS coherent acoustic, ATRAC, MPEG-2(AAC), etc. compression Media Film, DVD-Video, digital broadcast, games, etc.

Examples of lossless Method MLP (PPCM: Packed PCM), DST (Direct Stream Transfer) compression Media DVD-Audio, Super Audio CD

Examples of uncompressed formats

Media CH Encoding method fs [Hz] Qb [bit] Bitrate [bps]

CD 2ch LPCM 44.1k 16 1.4112M 96dB

Dynamic range

[dB]

DVD-Video 1 - 8ch* LPCM 48k, 96k 16, 20, 24 Max 6.144M Max 144dB

DVD-Audio

Super Audio CD 2ch

Within a maximum of 6.144 Mbps, “fs” and “Qb” can be specified in a scalable manner according to the number of channels.

Example) In the case of two-channel, maximum 96 kHz x 24-bit x 2 channels = 4,608 Mbps < 6.144 Mbps

** Within a maximum of 9.6 Mbps, “fs” and “Qb” can be specified in a scalable manner according to the number of channels.

However, only one or two channels are possible for fs=176.4k or 192k.

Examples) One or two channels; max. 192 kHz/24-bit, 4 ch; max. 96 kHz/20-bit, 5.1(6)ch; max. 96 kHz/16-bit

***

Va l ue in the audible bandwidth. Includes the effect of noise shaping from Delta-Sigma modulation.

1 - 44.1k, 88.2k, 176.4k,

5.1(6)ch**

LPCM

DSD

(Direct Stream Digital)

48k, 96k, 192k

2.8224M 1 5.6448M

16, 20, 24 Max 9.6M Max 144dB

More than

120dB ***

[Table 3-1] Examples of uncompressed formats

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Examples of lossy (irreversible) compression formats

Media CH Compression fs [Hz] Qb [bit] Bitrate [bps]

Dolby AC-3 44.1k 16 320k -

Film 5.1ch

DVD-Video

Digital broadcast (Japan)

1 - 5.1ch Dolby AC-3 48k 16, 20, 24

(1 - 7.1ch) DTS coherent acoustic 48k, 96k 16, 20, 24

1 - 5.1ch

APT-X100 (DTS)44.1k 16 882k -

ATRAC (SDDS) 44.1k 16 2.4M* -

MPEG-2 AAC 32k, 44.1k, 144 - 256k (2ch)

( LC profile) 48k, (96k)

* 8 channels (L, LC, C, RC, R, LS, RS, LFE) + backup (Lmix, Rmix, C', LFE') * 5.1ch or more channel

More than 16

320k - 384k (Multi)

224k**, 256k**, 320k**, 384k**,

448k**

754.5k**,

1.50975M**

Dynamic

range [dB]

•SDDS (film, ATRAC) allows 7.1 ch (8 ch) which adds LC (between L and C) and RC (between R and C) to 5.1 ch.

•Mandatory audio signals for DVD-Video: LPCM signal or Dolby Digital (AC-3) signal (MPEG signal is also required in TV system 625/50 regions). DVD-Video players must have Dolby Digital (AC-3) playback capability.

•Optional audio signals for DVD-Video: DTS, MPEG, SDDS

[Table 3-2] Examples of lossy compression formats

Examples of lossless (reversible) compression formats

Media CH Compression fs [Hz] Qb [bit] Bitrate [bps]

DVD-Audio 1 - 5.1(6)ch

Super Audio CD 2 - 5.1(6)ch

PPCM 44.1k, 88.2k, 176.4k*

(Packed PCM, MLP) 48k, 96k, 192k*

DST

(Direct Stream Transfer)

** Va l ue in the audible bandwidth. Includes the effect of noise shaping from

2.8224M 1 Max 14.99136M

*Only one or two channels at fs=176k or 192 k

Delta-Sigma modulation.

16, 20, 24 Max 9.6M Max 144dB

Dynamic range

[dB]

More than

120dB **

•Super Audio CD requires that a two-channel source be stored (discs containing only a multi-channel

source are not allowed).

•DVD-Audio allows either of two methods; storing both a two-channel source and a multi-channel

source, or storing only a multi-channel source together with downmixing coefficients provided as meta-data.

[Table 3-3] Examples of lossless compression formats

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2-3. Recording response

By “recording response” we mean the response allowed when the master tape produced by the studio is recorded onto the production target media. The response of each channel recorded on the media will depend on the encoding method and compression method as described above. In the case of analog recording, the response will depend on the specifications of the recording media. However for lossy compression (irreversible compression), it is important to note that “fs” and “Qb” do not directly determine the recording response (in particular, the dynamic range). Currently for most media, full-range recording is possible for all channels. However in the case of LFE and surround channels, there will be differences depending on the media.

2-3-1. LFE channel

For media that is recorded in Dolby DIGITAL, such as film and DVD-Video, the bandwidth is restricted to 120 Hz at the time of encoding*. This also applies to DTS. However in film, the range to 80 Hz is the recording band for the LFE channel of DTS. Similarly for the MPEG-2 used in digital broadcast (Europe), the upper limit of the LFE storage bandwidth is restricted to 125 Hz. In MPEG-2 AAC (digital broadcast, Japan), full-range recording is possible for encoding, but due to considerations of the propagation spectrum, there may be a bandwidth limitation on the LFE channel. Thus, it is necessary to be aware of the recording bandwidth of the LFE channel when the propagation system is taken into account (see ISO/IEC and ARIB). For music media (DVD-Audio, Super Audio CD), the LFE channel allows full-range recording in the same way as the main channels.

* To be precise, Dolby Digital can record signals of up to about 600 Hz on the LFE channel of DVD-

Video, but since the LFE channel LPF (fc=120 Hz) is applied by default as an option during encoding, it is best to consider 120 Hz as the upper frequency limit for recording and playback on the LFE channel except for special cases.

2-3-2. Surround channels (S, LS, RS, BS)

For 3-1 matrix (Dolby stereo, Dolby surround, DTS stereo), the recording bandwidth of the S channel is restricted to 100 Hz–7 kHz. For 5.0 matrix (Dolby Pro Logic II), the LS and RS recording channels are restricted to 100 Hz–20 kHz. In DTS for film (5.1, 6.1), the recording bandwidth of the surround channels (LS, RS, BS) is restricted to 80 Hz and above, but since sound recorded on the master tape that is lower than this point is collectively recorded on the LFE channel, the resulting playback is full-range. This is known as “bass management” (described in section 4).

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2-4. Playback response

By “playback response” we mean the desired (recommended) response of the playback system that plays back the media. For example, this corresponds to the frequency response of each speaker and the level balance. It is important to be aware that depending on the media and the channel format, playback response may not be the same as the recording response. The following pages describe playback response for typical media.

2-4-1. DVD-Video: Dolby, DTS

SPL [dB]

All-pass level

LFE : approx. 89dBC L=C=R=LS=RS : 85dBC LS=RS=-3dB : 82dBC

LFE

20 – 120Hz

AP(C)

31.5

[Fig. 10] Playback specification for DVD-Video program

1/3 octave band level

LFE : approx. 81dB L=C=R=LS=RS : approx. 71dB

LS=RS=-3dB : approx. 68dB

+10dB

L=C=R, LS=RS=BS (5.1ch, 6.1ch)

125

1/3 octave band center frequency [Hz]

200

315

500

800

LS=RS (3-1ch)

1.25k

Input Signal

Wide-band Pink Noise

approx. 0VU

(-20dBrms)

3.15k

20k

12.5k

In DVD-Video (Dolby, DTS), the playback level of the LFE channel (20–120 Hz) is set so that it will be +10 dB relative to the level of the main channel bands. In the case of 3-1, LS and RS are set approximately 3 dB lower so that the playback levels of L, C, R, and S (LS+RS) will be the same.

[Front channel]

Level

L = C = R (= 85 dBC) Match the playback level of all channels.

Playback bandwidth

Full-range

[Surround channels]

Level

3-1: S (LS+RS) = L/C/R (=85dBC)

Set the LS and RS playback levels lower than for 5.1 (LS = RS ≈ 82 dBC)

5.1: LS = RS = L/C/R (= 85 dBC)

6.1: LS = RS = BS = L/C/R (= 85 dBC)

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