[mythtv-users] AAC 5.1 over optical?

Richard Shaw hobbes1069 at gmail.com
Tue Aug 18 12:31:37 UTC 2009


On Tue, Aug 18, 2009 at 1:23 AM,
sonofzev at iinet.net.au<sonofzev at iinet.net.au> wrote:
> Hi All
>
> I've started to use mythnuv2mkv as a script to transcode my files.
> The limitation it has is that it can't just keep the ac3 audio instead of
> compressing to another format.
>
> I have found out that in future it may encode to 6 channel (5.1) AAC although I
> have read in many places that this can't be transmitted over optical.
>
> Can 5.1 AAC be transmitted over optical s/pdif in mythtv (maybe stream as ac3 or
> 6 channel mp3?)? Or do I have to look for another transocding solution if I want
> to keep 5.1 audio?
>
> cheers
>
> Allan

My understanding is that digital output is not inherently multichannel
(it's 2 channel PCM) but basically they apply the digital equivalent
of dolby pro logic encoding to get more channels out of a 2 channel
system. So yes, it's theoretically possible but you'd have to reencode
the stream into AC3 or DTS (or whatever your receiver can accept). I
wouldn't do that unless I had no choice, AC3 and DTS are compressed
streams so you will loose some quality. It would be better to get some
decent quality audio cables and just use the multichannel analog
inputs in your receiver.

Richard


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