I need some clarification about this.

So, let's say I have a M2TS file with a DTS-HD MA - let's assume it's in sync - and other audio tracks.
If I mux the audio and video streams into a MKV file, the DTS-HD MA would have a delay of 21ms - adding 21ms of silence in the beginning.

Now, if I mux back the streams into another M2TS file, would be the DTS-HD MA in sync again, or still retaining the 21ms delay?
And if I mux in another MKV, the delay would still be 21ms, or adds up and be 42ms?!?

I was under the assumption that the delay of 21ms only applies to DTS-HD MA tracks (or other formats as well) that are uncompressed to wavs (for syncing or other reasons) and then run through DTS-HD MA Encoder Suite (the software which introduces the 21ms delay) back to DTS-HD MA. Don't think any delay is added to untouched DTS-HD MA or EAC3to delayed tracks (including muxing and edits for delays) as long as it is not run through the above software. Am I wrong?.

So, if it's the DTS-HD MA Encoder Suite that adds the delay, it should apply to any container - hence also M2TS, MP4.

@Turisu we need your help!

Only DTS-HD MA created in DTS-HD MA Encoder suite has the delay of 21ms as far as I am aware. Plain muxing into mkv/editing of studio blu-ray/uhd DTS-HD MA (not created by one of us using this program) does not have the 21ms delay. Container does not have anything to do with it, again, as far as I am aware.

I don't think that's really the case X5gb

I've decoded and compared tons of DTHD x DTS-HD MA tracks on the same disc (usually Sony's UHDs) and on UHD x BD (usually Disney discs, that carry 7.1-Atmos on the UHD and DTS-HD MA 7.1 on the BD) and in just about any case (there might have been an exception, but I don't recall right now) the DTS tracks is 21ms or a little more offset from the dolby (with everything else like video, chapters and subtitles being in sync on both releases).

I've also compared the DTS-HD and regular DTS tracks with regular DD (sometimes dubs) on the same BD, and again, the DTS is usually 20 something plus offset in regards to the dolby track. That's also been the case on some DVDs I've tested with both DD and DTS tracks.

So in my understanding, every DTS encoded adds this +21ms that studios usually just ignore.

The most receent one was Free Guy UHD DTHD 7.1-Atmos x BD DTS-HD MA 7.1, and the difference was exactly +21ms for the latter.

ps: I would be nice if other users here can also perform this kind of comparison on discs, so we can broaden our understanding of this issue.


ps2: spoRv,
Unless you decode and re-encode to DTS-HD, the 21ms will remain and no other will be added. It's not related to muxing, just the actual encoding of the audio.
In other words, you can mux and demux multiples times and the DTS-HD MA track will remain the same if you don't set any forced delay (negative or positive). I have tested this on many occasions and compared the tracks with windiff.

Thanks for all the info, BDgeek!

So it seems that all DTS tracks - "vanilla" and HD - are 21ms "ahead", but... could be the contrary, and then Dolby be 21ms "behind"?

Would be nice to make some comparisons with PCM tracks!

A while ago I decoded a DTS-HD MA track from a M2TS in 'Fate/Zero' Japanese Standard Edition and compared it against the PCM track from the original Japanese 2-part release. No +21ms delay in the DTS-HD MA track.

Something I think pipefan suggested but no one was ever able to confirm is whether professional blu ray authoring programs know about this and set a delay to compensate for it.

BDgeek, my point to spoRv was that simply muxing does not create the delay, its the initial encoding that creates the delay, so at least I was half right. Thanks for the info re most of studio DTS-HD MA audio also having it as well, that I wasn’t aware.

I was under the impression that it is something the authoring software needs to 'see' but is discarded which is why DTS-MA tracks from professionally mastered blus do not have the header. Pipefan wrote a lot (a lot) about this so it's probably best to check his threads, also a hex editor would allow you to identify the presence if the header