DTS-HD Master 2.0: L/R or Lt/Rt?

[Dr. Cooper]

Hello everyone,

I'm currently working on a Blu-ray for which I have several PCM-tracks and a few DTS-HD Master 5.1/7.1-tracks. Since my BD-player seems to prefer Dolby Digital or DTS over PCM I now wanted to try, if I can get around this by converting the PCM-tracks to DTS-HD Master first.

The PCM-tracks are Mono and Stereo. For the Mono it's easy - I have to select 1.0 in the DTS-HD Master Suite. However, for the 2.0-tracks it confuses me as there are two options: L/R (Left / Right) and Lt/Rt (Left total / Right total). I already looked at the Manual, but couldn't figure out what's the difference.

Can anyone explain me what's the difference and which option I have to pick?

Thanks in advance!

[Beber]

I guess one of those is for 2.0 mono and duplicates the mono signal on both channels. My guess would be that the "total" is designed for that. But wait for someone who knows.

[TomArrow]

L/R is a simple stereo track.
Lt/Rt is basically Dolby Surround/Dolby Stereo, where 4 channels are matrixed into 2. I think in most cases this is probably what you're looking for. The compression is most likely the same, but the decoder will know that there is matrixed audio to be decoded this way.

[Beber]

Okay, so I was way off!

[TomArrow]

Okay, so I was way off!

Happens to the best of us.

[Dr. Cooper]

Thanks for the quick reply!
The 2.0-tracks are mostly Laserdisc- and TV-captures, so Lt/Rt should be the correct choice.

[TomArrow]

Yep. If the Laserdisc says "Dolby Surround" on it, it should be correct that way, unless they have made a mistake somehow. TV I don't know, haven't really looked into whatever conventions they might have had, especially with older analogue broadcasts. But I'm sure the information is available somewhere.

[Dr. Cooper]

The TV-track is from a digital broadcast, no idea whether it's Stereo or Dolby Surround and how I can find that out for sure. But the Laserdiscs all said "Dolby Surround" on the cover.

[TomArrow]

If you have the original stream captured without reencoding and it's AC-3, you might be able to tell:

http://stnsoft.com/DVD/ac3hdr.html

Apparently there's a tag in DD/AC3 called dsurmod, indicating this. However this also relies on the TV station broadcasting it properly ofc.

Not sure what tool would be able to read that tho.

[Dr. Cooper]

It really is AC3 and has been captured as broadcasted. However, I'm pretty sure there is no flag in it. A couple of years ago I had an AV-Receiver that showed when a surround-flag has been available, but I've only seen that on a single TV-station and other than that only on DVDs. All the others (including the station I recorded the track in question from) only aired L/R without surround-flag.