[mythtv-users] UK Freeview HD surround sound

[Jean-Yves Avenard]

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.

>
> 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