Audio Clarification

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Hoosier205 Online
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Post: #1
I just need to get a little clarification about something:

- It is my understanding that when using LPCM via OSX by turning off the passthrough option..."HD audio" DTS-MA or True HD formats are decoded before being transmitted, but only the core audio is used (standard DTS or Dolby) and sent to the receiver.

- It is also my understanding that when using the passthrough option in regards to "HD audio" only the core audio of the HD formats (standard DTS or Dolby) is being bitstreamed/transmitted to the receiver.

So, if your receiver is fully capable of either LPCM or HD Audio decoding...what is the advantage of using LPCM over passthrough?
(This post was last modified: 2014-08-06 20:32 by Hoosier205.)
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Memphiz Offline
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Post: #2
The advantage is that LPCM can be kept in sync with the video more easily then passthrough. Normally LPCM should be prefered to passthrough if possible. Though keep in mind that LPCM channel mapping was just fixed in the latest gotham release 13.2 and doesn't work correctly with older versions.

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(This post was last modified: 2014-08-07 10:23 by Memphiz.)
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jjd-uk Offline
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Post: #3
(2014-08-06 20:20)Hoosier205 Wrote:  - It is my understanding that when using LPCM via OSX by turning off the passthrough option..."HD audio" DTS-MA or True HD formats are decoded before being transmitted, but only the core audio is used (standard DTS or Dolby) and sent to the receiver.

XBMC can decode the full TrueHD 7.1 track to LPCM 7.1, there is only a restriction with decoding of DTS-HD as there is no open source implementation available, for DTS-HD it can be output as DTS 5.1 if passthrough is enabled (with DTS option selected) or LPCM 5.1 if passthrough is disabled.

(2014-08-06 20:20)Hoosier205 Wrote:  - It is also my understanding that when using the passthrough option in regards to "HD audio" only the core audio of the HD formats (standard DTS or Dolby) is being bitstreamed/transmitted to the receiver.
On platforms that support passthrough of HD audio the full 7.1 audio track is pass completely untouched, this is what passthrough means, however OS-X does not support passthrough of the HD audio codecs.
(2014-08-06 20:20)Hoosier205 Wrote:  So, if your receiver is fully capable of either LPCM or HD Audio decoding...what is the advantage of using LPCM over passthrough?

As Memphiz has said decoding to LPCM makes it easier for XBMC to maintain sync, although you do lose some fidelity for DTS-HD, however this is academic for OS-X where DTS-HD can't be passed through as is to a AVR anyway.
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Hoosier205 Online
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Post: #4
Sounds great and makes perfect sense. Thank you to both of you!
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