blu-ray, 7.1, and optical cables - AVS Forum
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post #1 of 8 Old 11-16-2010, 02:23 PM - Thread Starter
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Is it true that a blu-ray player will not pass 7.1 audio through an optical cable? If so, what causes this limitation? Bandwidth? Copy protection? HDCP? Promotion of new HDMI equipment (tv's, receivers, etc.)?
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post #2 of 8 Old 11-16-2010, 02:30 PM
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Coax or Toslink will give you up to 7.1 channels but not the lossless DTS MA or TRUE HD codecs found on Blu Ray. Just lossy DD and DTS / EX core mixes from a Blu Ray disc or from DVD.

Bandwidth is the issue for no TRUE HD / DTS MA over Tos / Coax. There is no HDCP with Tos / Coax - just HDMI and DVI.

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post #3 of 8 Old 11-16-2010, 02:44 PM - Thread Starter
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Are you saying that the problem is both bandwidth and hdcp? Is HDCP to protect both audio & video, or video only?

Where can I find a reference for bandwidth capacity of optical/toslink, coax, and hdmi?
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post #4 of 8 Old 11-16-2010, 03:49 PM
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The limitation is bandwidth for DTS and DD LOSELESS formats that are the new standard for BluRay.

The lossy formats used by HD broadcasts, DVD players, and most any video format OTHER than BluRay (or now defunct HD-DVD) would be carried by either optical or coaxial digital outputs.

I have no info on bandwidth of these connections, sorry.

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post #5 of 8 Old 11-16-2010, 04:14 PM
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Quote:
Originally Posted by thebland View Post
Coax or Toslink will give you up to 7.1 channels but not the lossless DTS MA or TRUE HD codecs found on Blu Ray. Just lossy DD and DTS / EX core mixes from a Blu Ray disc or from DVD.

Bandwidth is the issue for no TRUE HD / DTS MA over Tos / Coax. There is no HDCP with Tos / Coax - just HDMI and DVI.
Not true that Bandwith is an issue with TOSLINK.

The communication with the newest IBM mainframes (Z196) uses the TOSLINK fiber cables for FICON communications between DASD and other mainframes in a SYSPLEX is
FICON link data rate = 100 MB/sec (100MBps)
http://www-01.ibm.com/software/htp/t...s03/tgs03l.pdf

The Audio Codec is DTS-HD High Resolution.
The Audio Channels (sound scheme) can appear as 5.1 (most typical) or 7.1 (unusual).
Audio Fidelity data: the DTS-HD specification indicates it is 24 bits deep, and can be recorded at 48 kHz (typical for HD DVD) or 96 kHz (would probably be used for Blu-ray, but there aren't any).
Audio Bit Rate values can go as high as 6.144 Mbps for encoded data, but might be either 1.5, 4.5, or 6.144 Mbps, depending on the bandwidth that the studio decides to allocate to this type of audio track. Those HD DVDs that supported DTS-HD invariably used 1.5 Mbps bitrates
http://www.tomsguide.com/us/high-def...ew-1088-4.html

100MBps is a heck of a lot higher then 6.144Mbps

100 MB=100 Mbytes
6.1Mb=6.1 Mbits

Bits and Bytes
A bit is a single character of data (a 0 or a 1). A byte is eight characters of data. Therefore, eight bits make a byte. Your computer processes information in a series of eight bits, or, one byte.



Consumer optical/coaxial digital adhere to and are limited to the S/PDIF consumer specification.

It is not the cable that is the problem with 7.1 sound ,it is the implementation limited to the S/PDIF consumer specification
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post #6 of 8 Old 11-16-2010, 04:22 PM - Thread Starter
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So optical cables have huge bandwidth, but s/pdif bandwidth (what's the difference?) is less than that of lossless audio found on blu-rays. But even if bandwidth was not an issue, it still would not work because dts-ma and dolby truehd require hdcp. Is that correct?
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post #7 of 8 Old 11-16-2010, 06:54 PM
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s/pdif (Sony/Philips Digital Interface) is a protocol used with optical and digital coax connections. The spec limits it to 2 channels of PCM and lossy DD 5.1 and DTS. I have never found a good source explaining the reason for the limitation - bandwidth, copy protection, whatever. But, regardless of the reason, the limitations of s/pdif connections are clear.

If you want 7.1 or hires 5.1, you can't use an optical or digital coax connection.
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post #8 of 8 Old 11-18-2010, 04:33 PM
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Quote:
Originally Posted by thebland View Post

Coax or Toslink will give you up to 7.1 channels but not the lossless DTS MA or TRUE HD codecs found on Blu Ray. Just lossy DD and DTS / EX core mixes from a Blu Ray disc or from DVD.

If the lossless is dts-HD MA 7.1, you won't get 7.1 via SPDIF as the max for dts ES is 6.1 and I'm not even sure if it comes with the ES core in this case - if not then it's plain dts 5.1. Same with Dolby TrueHD: I'm not sure if it carries DD EX as companion track.

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