[mythtv-users] UK Freeview HD surround sound

[Andre Newman]

On 11 Jul 2013, at 14:08, Jean-Yves Avenard <jyavenard at gmail.com> wrote:

> Hi
> 
> On 11 July 2013 07:48, Chris Simmons <chris at simmons.titandsl.co.uk> 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 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.
> 
> you don't need to worry about this, myth will use the best option
> possible to play 5.1 according to your system,
> 
>> 
>> It seems unlikely that receivers will cope with AAC pass through (but I'm
>> guessing) and mythtv doesn't do this anyway - right?
> 
> myth doesn't support AAC passthrough, regardless of what some are saying.

Oops, that's why I can't recall exactly which tickbox it is :-O

Sorry and I guess that answers Paul's Marantz comment!

Andre

> 
>> 
>> So can mythtv convert to PCM or transcode to some other codec? Maybe alsa
>> can do it with sufficient hacking?
> 
> Ignore the other answers, they are completely wrong...
> 
> If your system only supports SPDIF out; then the 5.1 AAC LATM stream
> will be decoded internally as 5.1 LPCM, and then re-encoded as AC3 and
> then sent via SPDIF. There will be a slight loss of audio quality,
> it's not that obvious that you will be able to hear it though.
> 
> If your system supports 5.1 audio out (either analog or hdmi); then
> the audio will be decoded and sent as 5.1 LPCM; under this scenario,
> there's no loss of audio quality, the entire process is lossless.
> 
> Jean-Yves
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