understanding lossless 7.1 and their core

Random chit-chat and anything that doesn't belong elsewhere
Post Reply
daaceking
Regular User
Posts: 68
Joined: Mon Apr 28, 2014 9:06 pm

understanding lossless 7.1 and their core

Post by daaceking »

Hello

Dolby and DTS both use lossless audio on blu-ray and regularly use 7.1 channels. They both also use a 5.1 core. My question is, is there any difference in sound, by which i don't mean a lossless to lossy comparison. Nor do i mean difference in sound channels. I mean are there sounds that exist in 7.1 that don't exist in the core. Such as music, sound effects etc

Thanks
User avatar
Rodeo
HandBrake Team
Posts: 12722
Joined: Tue Mar 03, 2009 8:55 pm

Re: understanding lossless 7.1 and their core

Post by Rodeo »

The extra channels get downmixed into the core, just like the center and surround channels get downmixed into left & right when doing a Stereo downmix. Otherwise, since in most surround tracks, voices are found in the center channel, nobody would hear any voices when listening on any Stereo sound system! A bit inconvenient maybe?
daaceking
Regular User
Posts: 68
Joined: Mon Apr 28, 2014 9:06 pm

Re: understanding lossless 7.1 and their core

Post by daaceking »

Ah, i see! So modern hardware must
Upmix to lossless 7.1 then, because legacy equipment can't read the special data right?
User avatar
Rodeo
HandBrake Team
Posts: 12722
Joined: Tue Mar 03, 2009 8:55 pm

Re: understanding lossless 7.1 and their core

Post by Rodeo »

Don't quite understand what you mean here, sorry.
daaceking
Regular User
Posts: 68
Joined: Mon Apr 28, 2014 9:06 pm

Re: understanding lossless 7.1 and their core

Post by daaceking »

well, you said that the core basically has no sounds/music missing from the 7.1 lossless track.

older hardware [which is incapable of playing lossless audio] will play the core because that's why it exists [for compatibility]. so then to create a 7.1 system it uses the core & the "residual?" to create the 7.1 lossless track. so the only way it can do that is by upmixing. right? :-)
User avatar
Rodeo
HandBrake Team
Posts: 12722
Joined: Tue Mar 03, 2009 8:55 pm

Re: understanding lossless 7.1 and their core

Post by Rodeo »

In the case of DTS-HD, the decoder:

- decodes the DTS core

- decodes the HD extension

- adds up both signals (for more detail, please read the DTS specification)

In the case of TrueHD, the core Dolby Digital track is interleaved with the TrueHD track, but they're otherwise fully independent. The decoder decodes one substream and discards the other, depending on what it supports.

Upmixing, on the other hand, would be taking a signal with fewer channels than the sound system it's going to be played on (for example, playing a 5.1 stream on a 7.1 system, sometimes the surround/side channels will be repeated in the rear channels, or sometimes there may be some additional processing involved).
daaceking
Regular User
Posts: 68
Joined: Mon Apr 28, 2014 9:06 pm

Re: understanding lossless 7.1 and their core

Post by daaceking »

so with with the incorrect terminology excused and my layman terms, it's the same thing :-P

basically it's my original question where i'm asking if an old reciever that doesn't support dts-hd or truehd, or even if we're talking about libdca, whether every musical note and everysound effect still exists that would exist in the lossless audio whether it be the dts+hd extension or the parts which is ultimately truehd. :)
musicvid
Veteran User
Posts: 3911
Joined: Sat Jun 27, 2009 1:19 am

Re: understanding lossless 7.1 and their core

Post by musicvid »

Your hardware must be capable of decoding 7.1 in whatever digital flavor you feed it.
Format support in receivers varies greatly. If it's not stated on the front of the receiver, it likely doesn't support it.
It's that simple.
Post Reply