RME Audio Hammerfall HDSPe MADI FX, User Manual

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User's Guide HDSPe MADI FX © RME
30.7 Terminology
Single Speed
Sample rate range originally used in Digital Audio. Typical applications are 32 kHz (digital radio
broadcast), 44.1 kHz (CD), and 48 kHz (DAT).
Double Speed
Doubles the original sample rate range, in order to achieve higher audio quality and improved
audio processing. 64 kHz is practically never used, 88.2 kHz is quite rare in spite of certain ad-
vantages. 96 kHz is a common format. Sometimes called
Double Fast
.
Quad Speed
Doubles the double sample rate for ensuring hi-end audio quality and processing. 128 kHz is
non-existent, 176.4 kHz is rare, if at all then 192 kHz is used, e.g. for DVD Audio.
Single Wire
Standard audio data transfer, where the audio signal's sample rate is equal to the rate of the
digital signal. Used from 32 to 192 kHz. Sometimes called
Single Wide
.
Double Wire
Before 1998 there were no receiver/transmitter circuits available that could receive or transmit
more than 48 kHz. Higher sample rates were transferred by splitting odd and even bits across
the L/R channels of a single AES connection. This provides for twice the data rate, and hence
twice the sample rate. A stereo signal subsequently requires two AES/EBU ports.
The Double Wire method is an industry standard today with different names, like
Dual AES
,
Double Wide
,
Dual Line
and
Wide Wire
. The AES3 specification uses the uncommon term
Single channel double sampling frequency mode
. When used with the ADAT format, the term
S/MUX is commonly used.
Double Wire not only works with Single Speed signals, but also with Double Speed. As an ex-
ample, Pro Tools HD, whose AES receiver/transmitter only worked up to 96 kHz, used Double
Wire to transmit 192 kHz. Four channels of 96 kHz turn into two channels of 192 kHz.
Quad Wire
Similar to Double Wire, with samples of one channel spread across four channels. This way
single speed devices can transmit up to 192 kHz, but need two AES/EBU ports to transmit one
channel. Also called
Quad AES
.
S/MUX
Since the ADAT hardware interface is limited to Single Speed, the Double Wire method is used
for sample rates up to 96 kHz, but usually referred to as S/MUX (Sample Multiplexing). An
ADAT port supports four channels this way. With MADI S/MUX is used as well, to transmit up to
96kHz although the 48K Frame format is used.
S/MUX4
The Quad Wire method allows to transmit two channels at up to 192 kHz via ADAT. The
method is referred to as S/MUX4. With MADI S/MUX4 is used as well, to transmit up to 192 kHz
although the 48K Frame format is used.
Note: All conversions of the described methods are lossless. The existing samples are just
spread or re-united between the channels.
48K Frame
Most often used MADI format. Supports up to 64 channels at up to 48 kHz.
96K Frame
Frame format for up to 32 channels at up to 96 kHz. The advantage of this format against 48K
Frame using S/MUX: the receiver can detect the real (double) sample rate on its own and im-
mediately. With 48K Frame and S/MUX, the user has to set up the correct sample rate in all
involved devices manually.