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Dolby Digital
and
DTS
(Digital Theater Systems)
Digital Surround
These formats use “accurate but not identical” compression to encode
multichannel (5.1) audio onto a DVD or Blu-Ray disk.
Dolby Digital Plus
This format offers up to 7.1-channel surround sound, and is only available
on some DVD and Blu-Ray disks. It uses less compression than its Dolby
Digital or DTS counterparts, for a better reproduction of the original movie
soundtrack.
Dolby TrueHD
and
DTS-
HD
Both of these formats offer up to 7.1-channel surround sound, and are only
available on (some) Blu-Ray disks.
These formats use “accurate and identical” (sometimes referred to as
"lossless") compression to deliver soundtracks that are identical to the
movie studio's original audio master, for the closest possible reproduction
of the movie theater experience.
These lossless audio codecs can only
be sent out the HDMI output. A compatible HDMI surround receiver is
required in order to play these tracks.
PCM
This storage method is similar to what is found on a music CD. DVDs often
have a stereo PCM audio track. Some BD discs also feature multichannel
(5.1, 6.1, or 7.1) PCM soundtracks.
Multichannel PCM soundtracks are uncompressed audio that can
sometimes exactly match the quality of the studio master.
The
multichannel lossless PCM formats are only available on the HDMI
output. A compatible HDMI surround receiver is required in order to
play these tracks.
(Stereo PCM can be output over the SPDIF or TOSlink coax/optical audio
outputs)
A summary of these audio formats is shown in the table below:
Disk
Type
Possible Digital Audio Tracks on the disk
BD Player
Audio Output
Blu-Ray
Dolby TrueHD
DTS-HD
Dolby Digital Plus
HDMI
Blu-Ray and DVD
Dolby Digital
DTS
PCM
(BD - up to 7.1 channels @192 Khz)
PCM
(DVD - stereo only, up to 96 Khz)
SPDIF or
Toslink
All
Any selected digital track will be decoded, mixed with effects
and secondary channel, and converted to analog.
7.1 Analog
Outputs
(For a detailed description of the audio output capabilities of the BD player, see Appendix C)
Regardless of the type of codec used to store the movie’s audio track onto the disk, audio data is always
stored on a disk in a digital format. The BD player therefore has digital audio outputs, so that the digital
audio soundtracks on the disk can be sent straight to a surround-sound receiver, without any loss in
audio quality.
Not all surround-sound receivers are capable of playing back all of the digital audio codecs listed above.
In addition, some surround sound receivers can play pack PCM data, but the data must be sent to the
receiver at a slower rate that what is stored on the Blu-Ray disk.
