This presentation, created for the 2007 Audio Engineering Society UK Conference, describes how to distribute superior Ambisonic surround-sound audio content in a way that maximises its accessibility by requiring only standard surround replay equipment. It's a longer version of Part 4 of my Ionian University presentations.

1. Getting the Best
Surround Around
Peter Carbines & Richard Elen
Pyramedia Productions

2. Ambisonics

3. Ambisonics

4. Ambisonics
• Invented by Michael Gerzon
and associates in the 1970s.

5. Ambisonics
• Invented by Michael Gerzon
and associates in the 1970s.
• Is not based on ‘one channel/one speaker’:

6. Ambisonics
• Invented by Michael Gerzon
and associates in the 1970s.
• Is not based on ‘one channel/one speaker’:
• Instead, soundfield is captured or created,
transmitted and rendered at the listening
end for the speaker array available.

7. Ambisonics
• Invented by Michael Gerzon
and associates in the 1970s.
• Is not based on ‘one channel/one speaker’:
• Instead, soundfield is captured or created,
transmitted and rendered at the listening
end for the speaker array available.
• Analogous to a Postscript file/printer.

8. Ambisonics
• Two methods of transmission:

9. Ambisonics
• Two methods of transmission:
• B-Format (the studio
format):
sum & difference channels.

10. Ambisonics
• Two methods of transmission:
• B-Format (the studio
format):
sum & difference channels.
• UHJ stereo-compatible
matrix:
(typically 2-channel UHJ).

11. Ambisonics
• The conventional view:
“Ambisonics is recorded with a special
microphone/array.”

12. Ambisonic Mixing

13. Ambisonic Mixing
• The vast majority of
popular music is mixed
from multitrack.

14. Ambisonic Mixing
• The vast majority of
popular music is mixed
from multitrack.
• Ambisonics is particularly
good at this: for example,
it’s isotropic.

15. Ambisonic Mixing
• The vast majority of
popular music is mixed
from multitrack.
• Ambisonics is particularly
good at this: for example,
it’s isotropic.
• Main interest of
‘Ambisonic Mixing Group’.

16. Discounted options
for distributing Ambisonic recordings

17. Discounted options
for distributing Ambisonic recordings
• MLP can carry B-Format and offer flags
for DVD-Audio, HD discs

18. Discounted options
for distributing Ambisonic recordings
• MLP can carry B-Format and offer flags
for DVD-Audio, HD discs
• …sorry, not very many people can play them.

19. Discounted options
for distributing Ambisonic recordings
• MLP can carry B-Format and offer flags
for DVD-Audio, HD discs
• …sorry, not very many people can play them.
• Downloadable Ambisonic files
and software players

20. Discounted options
for distributing Ambisonic recordings
• MLP can carry B-Format and offer flags
for DVD-Audio, HD discs
• …sorry, not very many people can play them.
• Downloadable Ambisonic files
and software players
• …here or on the way – but not yet widespread.

21. Goals
for distributing Ambisonic recordings

22. Goals
for distributing Ambisonic recordings
• Method must be available now, today.

23. Goals
for distributing Ambisonic recordings
• Method must be available now, today.
• Everyone (with a surround system)
can listen.

24. Goals
for distributing Ambisonic recordings
• Method must be available now, today.
• Everyone (with a surround system)
can listen.
• Easy and cheap to originate content.

25. The Answer…
Decoding in the studio

26. The Answer…
Decoding in the studio
• Decode Ambisonics to speaker feeds.

27. The Answer…
Decoding in the studio
• Decode Ambisonics to speaker feeds.
• Place the speaker feeds signals on a
conventional multichannel medium
(eg DVD).

28. The Answer…
Decoding in the studio
• Decode Ambisonics to speaker feeds.
• Place the speaker feeds signals on a
conventional multichannel medium
(eg DVD).
• This is called…

29. G-Format
Decoding Ambisonics in the studio
G
…to 5.1-compatible multichannel surround.

30. G-Format
Advantages

31. G-Format
Advantages
• Anyone can play it (if you choose popular
encoding and distribution formats).

32. G-Format
Advantages
• Anyone can play it (if you choose popular
encoding and distribution formats).
• Producer controls the decoding process.

33. G-Format
Advantages
• Anyone can play it (if you choose popular
encoding and distribution formats).
• Producer controls the decoding process.
• High quality decoder can be used,
correctly configured.

34. G-Format
Challenges

35. G-Format
Challenges
• Lose the ability to render for your replay
array (a primary Ambisonic benefit).

36. G-Format
Challenges
• Lose the ability to render for your replay
array (a primary Ambisonic benefit).
• With some caveats, decode can be reversible.

37. G-Format
Challenges
• Lose the ability to render for your replay
array (a primary Ambisonic benefit).
• With some caveats, decode can be reversible.
• What array do you decode to?

38. G-Format
Challenges
• Lose the ability to render for your replay
array (a primary Ambisonic benefit).
• With some caveats, decode can be reversible.
• What array do you decode to?
• Decoder target array and listener array
may be different.

39. G-Format
Challenges
• Lose the ability to render for your replay
array (a primary Ambisonic benefit).
• With some caveats, decode can be reversible.
• What array do you decode to?
• Decoder target array and listener array
may be different.
• Possible risk of audio and/or localisation
degradation if lossy compression used.

40. G-Format
What decode array?
N
•
C
ITU? L R
30º
100–120º
Ls Rs

41. G-Format
What decode array?
N
•
C
ITU? L R
• Decoding Ambisonics 30º
to ITU 5.1 is
technically possible.
100–120º
Ls Rs

42. G-Format
What decode array?
N
•
C
ITU? L R
• Living rooms 30º
aren’t good 100–120º
for ITU.
Ls Rs

43. G-Format
What decode array?
N
•
C
ITU? L R
• Living rooms 30º
aren’t good 100–120º
for ITU.
• We have Ls Rs
rectangular
living rooms.

44. G-Format
Decode array
N
L R
• Rectangular Array.
Ls Rs

45. G-Format
Decode array
N
L R
• Rectangular Array.
• A standard
Ambisonic
configuration.
Ls Rs

46. G-Format
Decode array
• But narrow
N
or wide?
L R
Ls Rs

47. G-Format
Decode array
• But narrow
N
or wide?
L R
• 4-speaker
Ambisonics
supports side
ratios
between
1:2 & 2:1 Ls Rs

48. G-Format
Decode array
• We don’t know.
N
L R
Ls Rs

49. G-Format
Decode array
• We don’t know.
N
• A square layout L R
minimises
likely errors.
Ls Rs

50. G-Format
Decode array
• We don’t know.
N
• A square layout L R
minimises
likely errors.
• Nimbus also
found square
best. Ls Rs

51. G-Format
Decoder array and listener array may be different.
N
L R
Ls Rs

52. G-Format
Decoder array and listener array may be different.
• Fronts wider than ITU; N
L R
Ls Rs

53. G-Format
Decoder array and listener array may be different.
• Fronts wider than ITU; N
• Rears are narrower. L R
Ls Rs

54. G-Format
Decoder array and listener array may be different.
• Fronts wider than ITU; N
• Rears are narrower. L R
• But listeners may
well not have ITU!
Ls Rs

55. G-Format
Decoder array and listener array may be different.
• Fronts wider than ITU; N
• Rears are narrower. L R
• But listeners may
well not have ITU!
• Ambisonics is robust.
Ls Rs

56. G-Format
Decoder array and listener array may be different.
• Fronts wider than ITU; N
• Rears are narrower. L R
• But listeners may
well not have ITU!
• Ambisonics is robust.
• CF is not essential
(LFE not needed Ls Rs
at all!).

57. G-Format Sources
B-Format or 2-ch UHJ?

58. G-Format Sources
B-Format or 2-ch UHJ?
• Very little B-format originally
(No multitrack mastering capability)

59. G-Format Sources
B-Format or 2-ch UHJ?
• Very little B-format originally
(No multitrack mastering capability)
• This is now changing.

60. G-Format Sources
B-Format or 2-ch UHJ?
• Very little B-format originally
(No multitrack mastering capability)
• This is now changing.
• UHJ recordings are very common.

61. G-Format Sources
B-Format or 2-ch UHJ?
• Very little B-format originally
(No multitrack mastering capability)
• This is now changing.
• UHJ recordings are very common.
• How would they stand up against
modern multichannel?

62. G-Format Sources
B-Format or 2-ch UHJ?
• Very little B-format originally
(No multitrack mastering capability)
• This is now changing.
• UHJ recordings are very common.
• How would they stand up against
modern multichannel?
• Nimbus showed SFM recordings work.
What about Ambisonic mixes?

63. What decoder?

64. What decoder?
• Decode needed to be done in software.

65. What decoder?
• Decode needed to be done in software.
• Several decoders available on-line
(see www.ambisonic.net → tools).

66. What decoder?
• Decode needed to be done in software.
• Several decoders available on-line
(see www.ambisonic.net → tools).
• We chose Ambisonic.exe written by
Rhonda Wilson at Meridian Audio.

67. What decoder?
• Decode needed to be done in software.
• Several decoders available on-line
(see www.ambisonic.net → tools).
• We chose Ambisonic.exe written by
Rhonda Wilson at Meridian Audio.
• Originally created for Nimbus.

68. What decoder?
• Decode needed to be done in software.
• Several decoders available on-line
(see www.ambisonic.net → tools).
• We chose Ambisonic.exe written by
Rhonda Wilson at Meridian Audio.
• Originally created for Nimbus.
• UHJ and B-Format capability.

69. What decoder?
• Decode needed to be done in software.
• Several decoders available on-line
(see www.ambisonic.net → tools).
• We chose Ambisonic.exe written by
Rhonda Wilson at Meridian Audio.
• Originally created for Nimbus.
• UHJ and B-Format capability.
• Decodes to a rectangle (2:1 – 1:2).

70. Release coding & media
Requirements

71. Release coding & media
Requirements
• Available now.

72. Release coding & media
Requirements
• Available now.
• Not a future system.

73. Release coding & media
Requirements
• Available now.
• Not a future system.
• Thus not surround downloads
(ie must be a ‘packaged medium’).

74. Release coding & media
Requirements
• Available now.
• Not a future system.
• Thus not surround downloads
(ie must be a ‘packaged medium’).
• Widely supported.

75. Release coding & media
Requirements
• Available now.
• Not a future system.
• Thus not surround downloads
(ie must be a ‘packaged medium’).
• Widely supported.
• Must be popular and widespread.

76. Release coding & media
Requirements
• Available now.
• Not a future system.
• Thus not surround downloads
(ie must be a ‘packaged medium’).
• Widely supported.
• Must be popular and widespread.
• Thus not SACD, DVD-A.

77. Release coding
Two choices: Dolby Digital & dts
• Dolby Digital:

78. Release coding
Two choices: Dolby Digital & dts
• Dolby Digital:
• Extremely widespread,

79. Release coding
Two choices: Dolby Digital & dts
• Dolby Digital:
• Extremely widespread,
• Cheap encoder.

80. Release coding
Two choices: Dolby Digital & dts
• Dolby Digital:
• Extremely widespread,
• Cheap encoder.
• Compatible with Ambisonics?

81. Release coding
Two choices: Dolby Digital & dts
• dts:

82. Release coding
Two choices: Dolby Digital & dts
• dts:
• Very widespread,

83. Release coding
Two choices: Dolby Digital & dts
• dts:
• Very widespread,
• Cheap encoder.

84. Release coding
Two choices: Dolby Digital & dts
• dts:
• Very widespread,
• Cheap encoder.
• Compatible with Ambisonics.

85. Release coding
Two choices: Dolby Digital & dts
• dts chosen.

86. Release medium
Two choices: DVD & CD
• DVD-Video:

87. Release medium
Two choices: DVD & CD
• DVD-Video:
• Authoring application required as well as
surround encoder.

88. Release medium
Two choices: DVD & CD
• DVD-Video:
• Authoring application required as well as
surround encoder.
• Images required (even if rudimentary).

89. Release medium
Two choices: DVD & CD
• DVD-Video:
• Authoring application required as well as
surround encoder.
• Images required (even if rudimentary).
• Time required to build menu structure
etc.

90. Release medium
Two choices: DVD & CD
• CD-DTS

91. Release medium
Two choices: DVD & CD
• CD-DTS
• Encoder costs $99
(Surcode).

92. Release medium
Two choices: DVD & CD
• CD-DTS
• Encoder costs $99
(Surcode).
• Very quick to author.

93. Release medium
Two choices: DVD & CD
• CD-DTS
• Encoder costs $99
(Surcode).
• Very quick to author.
• Burn with simple PC CD-burning
application (eg EAC, Nero).

94. Release medium
Two choices: DVD & CD
• CD-DTS
• Encoder costs $99
(Surcode).
• Very quick to author.
• Burn with simple PC CD-burning
application (eg EAC, Nero).
• Very low production cost
(CD-R or pressing).

95. Will G-Format work?

96. Will G-Format work?
• Nimbus showed
UHJ single-point
mic recordings
worked.

97. Will G-Format work?
• Nimbus showed
UHJ single-point
mic recordings
worked.
• Early tests
suggested that
UHJ mixes didn’t.

98. Will G-Format work?
• Nimbus showed
UHJ single-point
mic recordings
worked.
• Early tests
suggested that
UHJ mixes didn’t.
• Luckily, early tests
were wrong.

99. First test disc

100. First test disc
• Started with the first Ambisonic
mixes ever made…

101. First test disc
• Started with the first Ambisonic
mixes ever made…
• …KPM Music Library tracks
mixed to UHJ for the Cunard hi-fi
show in 1981.

102. First test disc
• Started with the first Ambisonic
mixes ever made…
• …KPM Music Library tracks
mixed to UHJ for the Cunard hi-fi
show in 1981.
• Sourced initially from cassette.

103. First test disc
• Started with the first Ambisonic
mixes ever made…
• …KPM Music Library tracks
mixed to UHJ for the Cunard hi-fi
show in 1981.
• Sourced initially from cassette.
• Success!

104. Initial results
Planar B-Format

105. Initial results
Planar B-Format
• B-Format test recordings from
www.ambisonicbootlegs.net.

106. Initial results
Planar B-Format
• B-Format test recordings from
www.ambisonicbootlegs.net.
• Mixture of SFM and digital mixes.

107. Initial results
Planar B-Format
• B-Format test recordings from
www.ambisonicbootlegs.net.
• Mixture of SFM and digital mixes.
• Extremely impressive results.
(UHJ and B-Format sourced demos
played in the Council Room)

108. Full-length discs
UHJ
• Surprise Surprise
• Stereotomy
• KPM Library discs
• Collins Classics CDs
• Nimbus, Music from York
…and more.

109. Full-length discs
UHJ
• Surprise Surprise
• Stereotomy
• KPM Library discs
• Collins Classics CDs
• Nimbus, Music from York
…and more.

110. Full-length discs
UHJ
• Surprise Surprise
• Stereotomy
• KPM Library discs
• Collins Classics CDs
• Nimbus, Music from York
…and more.

111. Full-length discs
B-Format
• Nimbus NI5763:
Bridge, Elgar, Holst:
Concertos for Cello & Orchestra
Raphael Walfisch, cello;
Royal Liverpool Philharmonic Orchestra
conducted by Richard Dickins.

112. Full-length discs
B-Format
• Nimbus NI5763:
Bridge, Elgar, Holst:
Concertos for Cello & Orchestra
Raphael Walfisch, cello;
Royal Liverpool Philharmonic Orchestra
conducted by Richard Dickins.
• Halliday mic array
at Philharmonic Hall,
planar B-Format.

113. Full-length discs
B-Format
• Nimbus NI5763:
Bridge, Elgar, Holst:
Concertos for Cello & Orchestra
Raphael Walfisch, cello;
Royal Liverpool Philharmonic Orchestra
conducted by Richard Dickins.
• Halliday mic array
at Philharmonic Hall,
planar B-Format.

114. Tweaks
Adjusting the workflow

115. Tweaks
Adjusting the workflow
• Noise bursts between
tracks an issue.

116. Tweaks
Adjusting the workflow
• Noise bursts between
tracks an issue.
• Led to assembly of
complete disc master as a
single CD-DTS file.

117. Tweaks
Adjusting the workflow
• Noise bursts between
tracks an issue.
• Led to assembly of
complete disc master as a
single CD-DTS file.
• Use of .CUE files to tell
burning application the
TNO locations.

118. Final workflow
• Assemble tracks as multichannel or
individual WAV files. (Disentangle .AMB)
• Concatenate with digital silence between
tracks to create album file(s).
• Create .CUE file and edit as required.
• Decode to speaker feeds.
• Encode to CD-DTS.
• Burn disc from CUE file.

119. Future plans
• Create new B-Format mixes…
• Decode and release them!
•
Mastering system… VST plugins/Nuendo
• Multitrack material welcome!

120. GETTING THE BEST SURROUND AROUND
by Peter Carbines & Richard Elen
22nd UK Conference
© Pyramedia Productions MMVII

121. GETTING THE BEST SURROUND AROUND
by Peter Carbines & Richard Elen
22nd UK Conference
© Pyramedia Productions MMVII

122. Audio Engineering Society
22nd UK Conference