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[Help] How to unfold a stereo mix to its original Cinemascope channels

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Yesterday, I saw some information on blu-ray.com that caught my attention: Bad Day at Black Rock was released to theaters in both mono and four-track stereo. The latter has been used for Blu-ray, with the four tracks folded down into a 2.0 mix encoded in lossless DTS-HD MA 2.0.

Is there any software that will open a stereo file to see all the discrete channels? I want to “unfold” or “De-Matrix” the mix back to its original four LCRS channels.
You can "dematrix" somehow a Dolby Surround (or compatible) stereo track, but obviously not perfectly - it's a bit like to descramble a scrambled egg!

It's possible to use some free software like Foobar2000 and plugins to decode it , but AFAIK no software (even expensive one) is good as (a good) hardware decoder.
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
As far as playback goes, I think Neural-X does a decent job at playing matrixed audio in a modern setup.
I think all 4 channels are there, it's like a Dolby Stereo mix (424). So, I guess we must be able to hear the four channels with a home cinema with Dolby ProLogic: Left, Center, Right and Surround, even if the mono surround channel is almost empty (I think it was common in Cinemascope films of that era).

I don't understand why they didn't encode it as 4 track discrete. They rarely include such a track, there are a few exceptions such as “Garden of Evil” (also Cinemascope): the also included DTS-HD Master Audio 4.0 mix (recreating the four track stereo presentation of the original theatrical exhibition).(blu-ray.com)

I want to create a Cinemascope and Technirama project, and recover the original discrete 4.0 tracks from 2.0 tracks of some films. In a few cases it is possible to get the 4.0 digital tracks from the LDs but I have no LD player and no way to capture the audio. That's why I wanted to see what I can do with the 2.0 stereo tracks, I want to get 4 mono channels from that 2.0 stereo track and export them like LPCM 4.0 or DTS-HDMA 4.0. If you are interested in my project I can post which films I am referring to.
It's hard to find a 4.0 digital tracks from LD (AC-3 or DTS); I guess it's close to impossible...

But upmixing a PCM track from LD (or any lossless stereo from UHD-BD/BD/HD-DVD) is surely much better than use a compressed AC-3 track!

Now, I'm curious to know which films are you referring to! Big Grin
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
FYI most processors won't know what to do with LPCM in anything other then then 2.0, 5.1, or 7.1. I recommend DTS-HD for any projects using 4.0/4.1
(2022-09-24, 12:30 PM)spoRv Wrote: It's hard to find a 4.0 digital tracks from LD (AC-3 or DTS); I guess it's close to impossible...

But upmixing a PCM track from LD (or any lossless stereo from UHD-BD/BD/HD-DVD) is surely much better than use a compressed AC-3 track!

Now, I'm curious to know which films are you referring to! Big Grin

To give you an example, a Technirama film, "Sleeping Beauty". Digital Track Dolby Surround, 4 channels:

https://www.lddb.com/laserdisc/07894/951...ing-Beauty

Blu-ray is Dolby Digital 4.0 (lossy).

Would it be possible to extract a lossless 4.0 file from that LD? I imagine that only a lossless 2.0 stereo file could be extracted.
It's not possible to "extract" lossless 4.0 from the LD PCM 2.0, but only to dematrix it.
Can't say if it's better a dematrixed PCM 2.0 than a lossy AC-3 4.0, though...
Unless you use one very good hardware encoder - like the Shure HTS-5300 - probably it's better to leave it as is, and let the final user decode using their hardware setup (or listen to it in stereo).
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
I would respectfully disagree that a lossless PCM track would always be preferrable to a "Lossy" multichannel mix. Despite AC3 or DTS legacy being lossy, if, and if being the key word here, that is the only discrete source available it may be the way to go. Matrix decoding, even the advanced ones all have various limitations. For the older models some limitations mean increased noise and reduced dynamic range. In the end none will get you the separation of the discrete version.
Sometimes there's more important things then separation. Take a music-heavy track like Amadeus, the lossy ac3 tracks can't compete with the 2.0 LD track in fidelity.

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