[mythtv-users] UK Freeview HD surround sound

[Paul Gardiner]

On 11/07/2013 12:08, Andre Newman wrote:
>
> On 11 Jul 2013, at 12:39, Paul Gardiner <lists at glidos.net> wrote:
>
>> On 10/07/2013 22:48, Chris Simmons wrote:
>>> I'm thinking about buying a surround sound system.  Trouble is I'm using
>>> Freeview HD which uses AAC LATM (according to mythtv) for audio.  Some
>>> of this (e.g. Wimbledon Men's final) is in 5.1 surround sound.
>>>
>>> I read here
>>>
>>> http://www.bbc.co.uk/blogs/bbcinternet/2010/06/questions_around_surround_soun.html
>>>
>>>
>>> that the bitrate is too high for SPDIF
>
> When it is decoded to PCM, yes the bandwidth is too high, if it is passed through then SPDIF is plenty. BBC used AAC to save bandwidth over AC3 on the Freeview HD system so therefore the raw AAC must be smaller than equivalent raw AC3.
>
>
>>> so that means I'll have to get a
>>> HDMI receiver.  I'm using Nvidia+binary driver and I think its up to the
>>> job on that end.
>
> That's what I use, I think any card gt2xx or newer is good for 5.1 PCM, you need 4xx for HDAudio passthrough to work properly.
>
>>>
>>> It seems unlikely that receivers will cope with AAC pass through (but
>>> I'm guessing) and mythtv doesn't do this anyway - right?
>>>
>>> So can mythtv convert to PCM or transcode to some other codec?
>
> If you untick the AAC passthrough it will decode to PCM, 2 channel for spdif or 5.1 for hdmi.
>
> I use this for UK Freeview HD as my (reasonably modern 2yr old) surround amp doesn't know how to decode AAC.
>>
>> Mythfrontend can pass through aac latm. That'll be your best option.
>
> If you can find a surround amp that knows how to decode it, maybe the latest models can?
>
> I recall mention that some Pioneer amps can decode it and google popped this out:
>
> http://www.pioneer.eu/uk/page/products/av-receiver/choose.html
>
> But this doesn't really indicate if aac can be decoded from an spdif input, aac is not necessarily aac-latm btw, I'd stick with hdmi and let myth decode the aac, it works for me.

I have a Marantz NR1501. I'm pretty sure my frontend is passing through
when I play Freeview HD stuff. Away from home at the moment, but I'll 
check when I get back.