Bryston SP3, Руководство пользователя

Страница: 29 / 72

SP3 PREAMP / PROCESSOR
APPENDIX D: HDMI NOTES continued
HDMI Notes, Part 1 Page 3 of 4
highest resolution (video) and the highest number of audio channels that the SP3 declares
as available, and the highest sample rate
8
that is available in the media being played, still
supported by both the SP3 and a TV screen further down the HDMI device chain. This
is determined by the maximum capability of the SP3 (Video up to 1080p, 3D, color depth
36, audio 7.1 channels up to 192kHz sample rate). In some cases very long HDMI cables
(i.e 10m) become the limiting factor preventing establishment of the highest possible
video mode. In such cases the source device will often negotiate a lower video or audio
resolution format than the one that is possible over a shorter or a higher quality cable
9
.
Because the source-repeater-sink setup is capable of dynamically configuring itself over
HDMI as a whole, it may result in very different behavior than if the same devices were
connected using a different method, for example video through DVI and audio through
SPDIF, Toslink or analog RCA.
For example, if a multi source is being played and the audio receiver (SP3) suddenly
changes from multichannel speaker configuration, to 2 channels, which happens when the
headphones are plugged into headphone jack on the SP3 or when STEREO button is
pressed, then most players would automatically downmix the stream being played to
stereo, on-the-fly.
With HDMI it is the player which typically downmixes the
program format to stereo when headphones are plugged to
SP3. Without HDMI the downmixing to stereo takes place in
the SP3 rather than in the player.
PCM versus “bitstream”
Most DVD and Blue-ray players can be configured to output audio contents either as
PCM (or “Linear PCM”) or as “bitstream”. The former option makes the player decode
and covert the media format to an uncompressed PCM format which is the most
compatible. The latter option causes the player to transmit the digital contents of the
media “as-is” unconverted, down stream to the repeater (SP3) and the sink (TV). The
“bitstream” option relies on the audio decoding being performed in the SP3, and ensures
the highest quality. SP3 is capable of decoding virtually all common digital audio
format including the latest lossless formats such as DTS-Master and Dolby TrueHD, thus
it is recommended to use “bitstream” player setting.
8
Sample rate or “frame” rate (in this case “frame” and “sample” are synonyms) is the frequency of the
digital data frames. For example 44.1kHz is the repetition frequency of the whole data frames transmitted
from a standard Compact Disk (CD). One data frame is 16 to 24bits of digital data. Typical sample or
frame rates are 44.1kHz (CD), 48kHz (DVD), 88.2kHz (SACD), 96kHz (high end digital sources),
176.4kHz, 192kHz – future very high resolution audio sources. Frame rate shouldn’t be confused with the
bit clock rate which the clock frequency of the bits within each data frame. For example, for CD disk the
bit clock is 2.822MHz.
9
This is a part of the HDMI adaptive filter configuration feature. The sink measures the electrical quality
of the cable during handshake and can block transmission that is exceeding a capacity of the cable, forcing
the source to downgrade the stream to a lower resolution settings.