FLAC As good as DTS-HD??

[TeaPea]

Hey, I ripped my blu ray collection to my mac mini HTPC with the DTS-HD audio tracks, not realising it cannot pass the DTS HD stream to my receiver so it just uses the DTS (lower quality - which is frustrating)

I can easily convert the files from DTS-HD to FLAC using the latest version of MakeMKV, would FLAC be just as good as DTS-HD or other HD audio being that they're both lossless? Or is there some technical reason it's not?

Thanks for any helps.

Tom

[Romansh]

They're both lossless. FLAC usually has better compression efficiency.

DTS-HD does have some additional features not found in FLAC:

• embedded downmix coefficients
• DTS core track, which can be passed through over S/PDIF (FLAC requires HDMI)
• less ambiguous definition of channel masks and order
  • FLAC does define a way to indicate a channel mask, but many players will simply ignore it, and assume the channel layout based on the number of channels
  • There is currently no defined channel mask or order for 6.1/7.1; for example, HandBrake and MakeMKV don't use the same channel order for 6.1/7.1
    • HandBrake, 6.1 -> L R C LFE Cs/BC Ls/SL Rs/SR, 7.1 -> L R C LFE Rls/BL Rrs/BR Ls/SL Rs/SR
    • MakeMKV, 6.1 -> L R C LFE Ls Rs Cs, 7.1 -> L R C LFE Ls Rs Rls Rrs (AFAICT based on my testing)
    • …neither is correct at this point since nothing is defined in the FLAC specification

[TeaPea]

Hey Romansh
Thanks so much for your reply, this could really help me with my HTPC setup

That makes sense, so if I select the DTS-HD sound in makemkv and convert it to FLAC, i loose the embedded DTS file?
But then from my perspective I do not need this file, as all I use the sound for is to send it to my Arcam AVR600 via HDMI.

The issue is, the mac mini cannot pass DTS-HD via HDMI as its not capable of it, something to do with drivers in OSX!
If I convert the files to FLAC though I can I assume pass this down HDMI to my AV receiver

Is that right? thanks again for your help, this is going a bit over my head! Bit of a minefield isn't it.
I think most my files are in 5.1 anyway and I only have a 5.1 setup and I doubt I will going 7.1 as it doesn’t seem worth it as sod all is in 7.1!

Cheers,
Tom

[Romansh]

I think most my files are in 5.1 anyway and I only have a 5.1 setup and I doubt I will going 7.1 as it doesn’t seem worth it as sod all is in 7.1!

Well, you can't choose whether your sources are 5.1 or not… if you want 5.1 out of a 6.1 or 7.1 source, you're stuck with decoding MakeMKV's FLAC output, downmixing to 5.1, then re-encoding to FLAC (which can take from 1 to 4 steps depending on how you do it)… possible, but annoying.

[mike admin]

1. There is an one-to-many relationship between track in input file and output file. You can create a profile that saves a track both as FLAC and DTS. Specifically, if you open a source with DTS-HD track, select "FLAC" profile and enable both DTS-HD tarck and DTS core, your output will have two audio tracks produced from the same source track. One would be DTS 5.1 copied as is and another would be DTS-HD track copied as FLAC. So you'll get a slightly bigger file but will keep the SPDIF-streamable DTS core.

2. MakeMKV uses channel order and channel bit mask as specified in Microsoft wavex specification. This is exactly the same channel order and channel mask that is used by libav/ffmpeg .

[Romansh]

2. MakeMKV uses channel order and channel bit mask as specified in Microsoft wavex specification. This is exactly the same channel order and channel mask that is used by libav/ffmpeg .

I'll send you a sample channel check, but:

1) MakeMKV does Ls Rs Cs for DTS-HD 6.1, and Ls Rs Rls Rrs for DTS-HD 7.1

2) Libav/FFmpeg map Ls/Rs to side channels, not back (for FLAC and several other codecs), thus expect Cs Ls Rs and Rls Rrs Ls Rs

…I should mention I've only tested raw LPCM. Maybe MakeMKV reorders the channels before encoding to FLAC?