Dolby Digital 2.0/5.1 transcoded from the HE-AAC stream in the HD mux may well be mixed to a different standard: (Film mix vs TV mix is 8dB lower, I believe)...
Thus a PCM stereo SD channel may well sound louder than a DD channel on HD when the HDR-Fox-T2 is set to output surround.... That is what the volume control (of the SD channels in PCM is for... to match the DD HD channel levels).
For many of us max could be close enough...
IIRC once upon a time I had it under max for channel surfing when using the PVRs in surround (though it could well have been the Foxsat-HDR rather than the -T2)... but found that the decoding delays were "annoying" when switching between DD and PCM. So we use the stereo decoding setting for HD most of the time.
NB for the BBC (as I understand it) the exact same transport stream includes Dolby-E encoded sound data that is sent to both DVB-T and DVB-S coding and multiplexing sets... Satellite uses Dolby proper and Terrestrial is transcoded (with an ability to mix in Audio Description - that is carried on satellite as a separate stereo PCM stream)...
AIUI the down-mix from 5.1 to stereo is based on the metadata in the Dolby E stream... and set by the programme producers... It certainly will NOT remove the surround (or LFE) channels (they may contain important information for the production!!).
Quite often the mixes are such that good ole Dolby Surround receivers can recover phase-encoded differences very effectively to steer sound in a very effective pseudo surround way.
Useful on iPlayer, for instance.
NB The same tech standards for video and audio delivery to playout is used by all the PSBs...
On satellite all C5HD content is flagged as 5.1... whether a stereo mix or not. Go figure.
Thus a PCM stereo SD channel may well sound louder than a DD channel on HD when the HDR-Fox-T2 is set to output surround.... That is what the volume control (of the SD channels in PCM is for... to match the DD HD channel levels).
For many of us max could be close enough...
IIRC once upon a time I had it under max for channel surfing when using the PVRs in surround (though it could well have been the Foxsat-HDR rather than the -T2)... but found that the decoding delays were "annoying" when switching between DD and PCM. So we use the stereo decoding setting for HD most of the time.
NB for the BBC (as I understand it) the exact same transport stream includes Dolby-E encoded sound data that is sent to both DVB-T and DVB-S coding and multiplexing sets... Satellite uses Dolby proper and Terrestrial is transcoded (with an ability to mix in Audio Description - that is carried on satellite as a separate stereo PCM stream)...
AIUI the down-mix from 5.1 to stereo is based on the metadata in the Dolby E stream... and set by the programme producers... It certainly will NOT remove the surround (or LFE) channels (they may contain important information for the production!!).
Quite often the mixes are such that good ole Dolby Surround receivers can recover phase-encoded differences very effectively to steer sound in a very effective pseudo surround way.
Useful on iPlayer, for instance.
NB The same tech standards for video and audio delivery to playout is used by all the PSBs...
On satellite all C5HD content is flagged as 5.1... whether a stereo mix or not. Go figure.
