Re: I/O device with multiple *independent* SPDIF ports?
Re: I/O device with multiple *independent* SPDIF ports?
- Subject: Re: I/O device with multiple *independent* SPDIF ports?
- From: "Mikael Hakman" <email@hidden>
- Date: Tue, 22 Jan 2008 14:01:30 +0100
- Organization: Datakonsulten AB
That sounds cool -- which FW device is that?
What is the FireWire interface with 32-bit integer format for digital
audio (SPDIF)? Does it need a special driver to work with a Mac?
It's RME Fireface 800. According to User's Guide there are drivers for both
operating systems on the disk, and installation procedures are well
described.
P.S. DTS only uses the lower 14 bits of the audio sample, so that the
digital noise is at -12 dB. Seems like a shame to lose 96 kbps of
bandwidth.
Not only that! If you look at the actual content of SPDIF when transmitting
DD or DTS then you'll see that large parts of each block do not transmit any
information at all. All samples are set to zero. This is because compressed
data, even for 6 channels, require much fewer bytes than 2 channels PCM for
corresponding time length. Each block in SPDIF is of fixed byte length, and
for given rate, also of fixed time length. Therefore they have to fill it
with zeros when actual data for this time length is shorter. Talk about
wasting bandwidth! All this seems to steam from the fact that SPDIF was
designed to transfer digital audio *signals* as opposed to *data*. Then
someone come up with the brilliant idea of sending compressed data through
it. Then AES adopted all this, and now we are where we are.
Regards/Mikael
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