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True 32 bits of SPDIF interface (new IC specification)  ??
True 32 bits of SPDIF interface (new IC specification)  ??
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Old 25th October 2014, 11:27 AM   #1
kfshu2 is offline kfshu2  Taiwan
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Default True 32 bits of SPDIF interface (new IC specification) ??

True 32 bits SPDIF interface,

ComTrue Inc. - Products



ComTrue Inc. launched a web page for their new audio bridge.

SPDIF support 384kHz/32-bits/SRC-32/Dop ??
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Old 25th October 2014, 02:52 PM   #2
Julf is offline Julf  Europe
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As far as I know, the SPDIF standard doesn't support 32 bits.
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Old 25th October 2014, 03:23 PM   #3
kfshu2 is offline kfshu2  Taiwan
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Default SPDIF new specification 32-bit ?

Is this true 32bits ??

http://www.comtrue-inc.com/images/eichhornia_7301_C.pdf


look like really new specification about SPDIF in datasheet, page 14.

??
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Old 25th October 2014, 04:31 PM   #4
tonyshih is offline tonyshih  Taiwan
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According to the specification, it has an "extend mode" to support 32bit format . Does anyone get more information about this chip?
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Old 25th October 2014, 05:53 PM   #5
twest820 is offline twest820
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The figure on page 14 of the CT-7301C datasheet looks like a bug. Or maybe it's just cryptic. What it labels a frame is a pair of time slots with incorrect subframing. The 24 bit case in the figure is seems incorrect as it omits the aux channel and the 32 bit case is either invalid or a proprietary extension.

What seems more plausible is the extend mode uses the aux channel to ship 28 bit rather than 24 bit samples. This would help a bit (well, four bits) in systems with poor gain structure. With decent gain structure it's functionally irrelevant.
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Old 25th October 2014, 06:23 PM   #6
Julf is offline Julf  Europe
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In any case it is pretty academic, as there aren't any 32 bit recordings.
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Old 25th October 2014, 06:40 PM   #7
kfshu2 is offline kfshu2  Taiwan
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Is this true 32bits ??

http://www.comtrue-inc.com/images/eichhornia_7301_C.pdf


look like really new specification about SPDIF in datasheet, page 14.

??


page 2, table ????

I2s32 <=> spdif32 768khz / 384khz ??????
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Old 25th October 2014, 09:07 PM   #8
twest820 is offline twest820
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Quote:
Originally Posted by Julf View Post
In any case it is pretty academic, as there aren't any 32 bit recordings.
Heh, in many recording situations it's nontrivial to get 70dB acoustic SnR, which is all of 6.13 bits. Some allowance for recording dynamic range, the ear's level tracking behavior, and ability to hear structured artifacts 20 dB or so below the noise floor yields the 16 bit standard. Digital volume at the source and common gain structure problems make 24 bit handy but I've never encountered a push to DAC case where more than 24 bit over SPDIF added value.

Where 32 and 64 bit are valuable is handling numerically stiff (low frequency) IIR filters as it's normal to need 16 signal path guard bits in deep bass and substantially more than that internal to the filter. There are cases where a SPDIF link ends up in the middle of a filter bank but they're rather obscure. People will buy 32 bits anyway because more must be better, though. So it's technically academic but useful in marketing.

Quote:
Originally Posted by kfshu2 View Post
page 2, table ????
If you want to get anywhere with this I'd suggest asking Comtrue. There's insufficient information in the datasheet on their website for meaningful conclusions to be reached. You may find it useful to look at how ADAT Lightpipe works and do workback math on the Toshiba and Everlight parts called out in the eval board---that should help you understand the 384k limit on the SPDIF side.

Alternatively, if this product announcement indicates you're associated with Comtrue it would be appropriate to disclose the relationship and work to improve the datasheet so that it's clear as to the protocol used and interface requirements and reaches characterization parity with competing parts with other vendors. If the intention's to generate buzz about the part the proper forum to post in is the Vendors' Baazar.
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Old 26th October 2014, 04:20 PM   #9
HpW is offline HpW
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Quote:
Originally Posted by kfshu2 View Post
True 32 bits SPDIF interface
Well, you define a missing/additonal format what ASES3 (protocol) do not have. Your format is block aligned to 40 bits

The current situation is, that ALL ADC/DAC do not fully provide a real 24 bit performance also within the full freq. range, likely 22..23 bits or even less (marketing format).

I would rather see a more open transportation format as supporting float format support too.

my 2 cents

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Old 26th October 2014, 06:09 PM   #10
Julf is offline Julf  Europe
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Quote:
Originally Posted by HpW View Post
I would rather see a more open transportation format as supporting float format support too.
I assume you are joking.
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