How was matrixed audio mixed?

[stwd4nder2]

Something I've always wondered but was never able to find a good answer to. How was audio mixed back in the Dolby Stereo days? Did they mix a discrete 4.0 track and then just convert it to DS, or did they mix it as stereo with an understanding of what would get matrixed out to different channels?

[alexpeden2000]

Something I've always wondered but was never able to find a good answer to. How was audio mixed back in the Dolby Stereo days? Did they mix a discrete 4.0 track and then just convert it to DS, or did they mix it as stereo with an understanding of what would get matrixed out to different channels?

I'm sure Pipefan did a good post on this, perhaps someone can rememebr which thread it was in and link it.

Something I'd like to know, if you're editing a 2.0 Matrix track to sync will it lose anything during the process or it the 'matrixing' done by the receiver afterwards anyway?

[PDB]

Did they mix a discrete 4.0 track and then just convert it to DS

There is more nuance to it but that's the gist.

[allldu]

Something I'd like to know, if you're editing a 2.0 Matrix track to sync will it lose anything during the process or it the 'matrixing' done by the receiver afterwards anyway?

It won't lose anything. The matrixing is in the mix.

[deleted user]

I think the way you were supposed to do it is, do a 4.0 mix, but, do then pipe the 4.0 output into a Dolby SEU4 (the encoder unit) and daisy chain the output of the SEU4 into an SDU4 (the decoder unit) and monitor it like that in order to see if it sounds good.

[stwd4nder2]

So if every DS mix stems from a 4.0, why isn't it more common for the 4 channel mix to be released on BD over the 2 channel DS? Or even as 5.0 with mono surrounds. I'd assume it would be more accurate to the original theatrical presentation then matrixed audio on a modern processor.

[ac3]

Am guessing cause there's no Bass that gets routed to the subwooofer without special decoding. On ffdshow I need to enable lfe cross over for it to work with movies that are 1.0 and 4.0. That's probably why so many get remixed in 5.1

[stwd4nder2]

Am guessing cause there's no Bass that gets routed to the subwooofer without special decoding. On ffdshow I need to enable lfe cross over for it to work with movies that are 1.0 and 4.0. That's probably why so many get remixed in 5.1

You should have your crossovers always on and configured correctly anyways. The LFE channel isn't meant to just be filtered bass from the other channels.

[spoRv]

FYI: Dolby Surround (as any other matrix encoding/decoding techniques) is NOT a lossless procedure: if you input your 4 channels into a DPL encoder, then the result Lt-Rt (Left total and Right total) in a DPL decoder, the final 4 channels, albeit very similar (how much depending on the quality of the encoder/decoder used) will never be identical.

This could be a reason why there are 2.0 tracks instead of 4.0 (4.1 or 5.1) tracks.

At the same time, if you want to hear a Dolby Surround track as much as possible similar to the one heard in a cinema at the time, it's better (IMHO and other's) to decode it with a good Dolby Pro-Logic decoder (Dolby SDU4 for example, as it uses the same chip found in cinema decoders) instead of let the new Dolby Surround Upmixer take care of it.

[ac3]

i remember when i had an AV reciever it didnt route bass to the subwoofers in 1.0 or 4.0 no matter what i did. it still doesnt in vlc
with kodi and ffdshow doing the decoding i need to go into the LFE options on ffdshow for bass to work on those formats.
i imagine they matrix it or remix it to 5.1 so consumers dont get pissed off when the subwoofer isnt doing anything
not sure why they keep releasing mono movies in 1.0 as well .
least when it's 2.0 the lfe works in pro logic.