[Help] 5.1 to 4.0 down convert

[uVSthem]

The Japanese UHD of King Kong vs. Godzilla from 1963 has the original 4.0 mix packed as DTS-MA 5.1. The LFE channel is empty and the two back channels are identical. What is the correct way to convert this to FLAC 4.0 or DTS-MA 4.0? Is this even something worth doing?

[stwd4nder2]

Most processors won't handle 4.0 in any LPCM format, you'd have to use DTS. Just take the 3 front channels and one of the rears and encode it.

 Is this even something worth doing?

No

[LucasGodzilla]

The Japanese UHD of King Kong vs. Godzilla from 1963 has the original 4.0 mix packed as DTS-MA 5.1. The LFE channel is empty and the two back channels are identical. What is the correct way to convert this to FLAC 4.0 or DTS-MA 4.0? Is this even something worth doing?

Personally I'd imagine removing the empty channels would do the trick since the channel order will automatically be detected as an LCRS setup I believe.

That said, whether or not the user above me is right about whether or not this is only supported by DTS, I don't know. I will agree though that unless there is a specific reason to making it a FLAC in the first place (such as for syncing to a video source with missing frames), just stick to syncing the DTS 5.1 instead.

[uVSthem]

The Japanese UHD of King Kong vs. Godzilla from 1963 has the original 4.0 mix packed as DTS-MA 5.1. The LFE channel is empty and the two back channels are identical. What is the correct way to convert this to FLAC 4.0 or DTS-MA 4.0? Is this even something worth doing?

Personally I'd imagine removing the empty channels would do the trick since the channel order will automatically be detected as an LCRS setup I believe.

That said, whether or not the user above me is right about whether or not this is only supported by DTS, I don't know. I will agree though that unless there is a specific reason to making it a FLAC in the first place (such as for syncing to a video source with missing frames), just stick to syncing the DTS 5.1 instead.

What software would recommend for this?

[Turisu]

Removing one of the surround channels would reduce the perceived volume of the rear audio by 3dB. So you'd need to increase the gain on the remaining channel to compensate (assuming this was taken into account when the 5.1 was mixed).

[uVSthem]

I gave it shot as a learning experience. Here is a link to the file if someone would like to test it out for me.

https://mega.nz/file/9RkkSQCY#OpBfJsp0dY...1Qo3aJ-6LA

I don't know if it needs the -21ms delay added for MKVs that I read about on the forums. If someone can let me know, please do.

[Turisu]

Yes, if muxing into an MKV, it would need the -21ms offset to remove the header data added by the DTS-HD encoder.