Backup and change audio in FFMPEG

[iXDanXi]

Hi all,

Been a while since I needed to ask a question.
In case it matters the disc I'm trying this on is Casino Royale the 4k UHD Steelbook release.

I do the following;
a decrypted backup
An MKV file of a title from the decrypted backup

I used to keep the audio titles as is, but then if a title contained a DTS HD track I'd need to run FFMPEG to convert the audio to ac3
(Previously asked a question in viewtopic.php?p=89808#p89808)

Now for consistency I'm thinking Dolby Audio as well as DTS should all be converted to the same and every time I try it comes out lossy.

My questions are;

1. What (if any formats would give me lossless identical audio with the same number of channels etc)?
Could anyone help with the FFMPEG command line?

2. Could I skip making an MKV of a encrypted backup using FFMPEG?
It looks possible as I've read somewhere you can stream from MakeMKV, cant find the link though

3. If you take the full track with extended audio only and not the core in addition am I right in saying the core is embedded so would still work on audio devices that cant support the extended metadata?
(I think ticking all audio copies the core twice).

4. With Dolby Vision support is it possible to get both HDR and Dolby Vision in same file or do you have to choose?

Thanks

[dcoke22]

My home theater receiver can't decode DTS-HD or TrueHD lossless audio, so I convert those audio tracks to FLAC when I create the .mkv file with MakeMKV. My player can decode FLAC and output it as PCM audio, which my receiver can play.

[iXDanXi]

Sorry - do you know of a good guide or can you point me in the right direction?
I didnt know MakeMKV could transpose.

Thanks

[dcoke22]

do you know of a good guide or can you point me in the right direction?

viewtopic.php?f=10&t=4776

MakeMKV has this notion of 'conversion profiles' for audio. While a .mkv file is being made, the conversion profile is employed to convert audio to a different format. By default it just copies the audio, unchanged, into the .mkv file. There's a built-in preset to convert multichannel audio to FLAC, which is probably what you're after.

[iXDanXi]

Thanks for this- really appreciated.
Cant believe I've never noticed that before.