Pioneer VSX-D3S User Manual
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APPENDIX C: DOLBY AC-3 SURROUND
THE LASER DISC FORMAT
The one major concern when the idea of incluiding another form of audio on a laser disc was .... Backwards Compatibility. It would not
do the laser disc format any justice, especially in a time of growing acceptability, to change the audio system without considering those
consumers that had already purchased a laser disc player. Thus to maintain backward compatibility, the AC-3 encoding was deemed
to be stored in one of the existing analog tracks.
do the laser disc format any justice, especially in a time of growing acceptability, to change the audio system without considering those
consumers that had already purchased a laser disc player. Thus to maintain backward compatibility, the AC-3 encoding was deemed
to be stored in one of the existing analog tracks.
The above diagram shows the format of the AC-3 Pro-Logic laser disc. The PCM audio track, containing the 4-channel matrixed digital
soundtrack, was fully maintained for continued use in laser disc players with digital capabilities. As mentioned above, one of the analog
channels will now contain the AC-3 encoding, while the other analog channel will contain a mono analog soundtrack, which still provides
backwards compatibility with those pre-1984 laser disc players (1984 was the year we introduced an LD player with digital capabilities).
soundtrack, was fully maintained for continued use in laser disc players with digital capabilities. As mentioned above, one of the analog
channels will now contain the AC-3 encoding, while the other analog channel will contain a mono analog soundtrack, which still provides
backwards compatibility with those pre-1984 laser disc players (1984 was the year we introduced an LD player with digital capabilities).
THE ADVANTAGES OF AC-3 OVER PRO-LOGIC
AC-3 is called a 5.1-channel system because it provides 5 independent channels (left, right, center, left surround, and right surround),
all reproducing a 20 – 20,000 Hz range. In addition, the system provides for an independent sub-woofer channel, which is called a low
frequency effects channel. Use of the low frequency effect channel is optional, since the 5 channels provide a full frequency bandwidth,
but available for those consumer wishing to include a sub-woofer for thunderous bass reproduction. Furthermore, AC-3 provides
improved channels separation, multi-directional discrete capability, and increased sound-design creative flexibility (for the movie
makers). Below highlights some of the other advantages of Dolby AC-3:
all reproducing a 20 – 20,000 Hz range. In addition, the system provides for an independent sub-woofer channel, which is called a low
frequency effects channel. Use of the low frequency effect channel is optional, since the 5 channels provide a full frequency bandwidth,
but available for those consumer wishing to include a sub-woofer for thunderous bass reproduction. Furthermore, AC-3 provides
improved channels separation, multi-directional discrete capability, and increased sound-design creative flexibility (for the movie
makers). Below highlights some of the other advantages of Dolby AC-3:
Available Channels on Disc
Playback Channels
Description of Playback Channels
Sound Processing
Surround Channel Maximum
Frequency Response
Frequency Response
Other Information
DOLBY SURROUND DIGITAL (AC-3)
5.1 Channels
5.1 Channels
Left, Right, Center, Left Surround, Right
Surround, and Sub-woofer
Surround, and Sub-woofer
Discrete Digital AC-3
Encoding & Decoding
Encoding & Decoding
20,000 Hz
- 5 Discrete Channels
- Fully Backward Compatible with
- Fully Backward Compatible with
Dolby Surround
- High Dynamic Range
- Extremely Accurate and Natural
- Extremely Accurate and Natural
Sound for Vocals and Effects Imaging
DOLBY SURROUND PRO-LOGIC
2 channels
4 channels
Left, Right, Center, and Surround
Analog Matrix Processing for Dolby Surround
7,000 Hz
2 4 6 8 10 12 14 MHz
Digital (PCM)
Audio
Dolby AC-3
Digital Audio
Analog Mono
Audio
Analog Video
Dolby AC-3
Digital Audio
Analog Mono
Audio
Digital (PCM)
Audio
Analog Video