I'll keep reading if this has been answered, so I'm sorry that this is rather old.nekno wrote: ↑Sat Feb 12, 2022 1:37 amEncoding DTS-HD takes in a lossless LPCM stream, encodes a lossy DTS core, and saves the rest of the discarded audio as lossless extensions. When decoding, the extensions are recombined with the lossy DTS core and decoded to arrive at the original lossless stream.FubbAyH wrote: ↑Fri Feb 11, 2022 11:04 pmYeah, I've been trying to figure out if that's possible too. My guess is that because the TrueHD is based on the AC3 core, when you add the core it needs to re-encode the TrueHD too to match? (which I'm presuming is why it takes a while) So maybe it's possible to create a core that doesn't need the TrueHD data to be re-encoded, but I don't know anywhere near enough about the details of AC3 or TrueHD to knowRESET_9999 wrote: ↑Fri Feb 11, 2022 3:09 pmthis seems to take the same processing time as converting the core to regular 640kbps 5.1...
is there a way to generate an ac3 core without re-encoding like they are trying to do in tsmuxer? even if the core is silent, I don't mind as long as TrueHD works.
Thank you for your scripts too!
But TrueHD doesn't require an AC3 lossy core; it isn't a required part of the TrueHD spec. When an AC3 core is included with a TrueHD track it's because of the BD spec, where it's required for BD / UHD BD.
TrueHD tracks are comprised of "access units" where the audio has been divided into frames.
A TrueHD+AC3 track has audio frames alternating between TrueHD and AC3. It's just two completely separate streams interleaved into a single track, kind of how STDL puts two distinct video streams into separate NALUs of a single track.
A THD+AC3 track is the STDL of TrueHD audio streams, where a THD track with a separate AC3 track is DTDL.
So if you have a TrueHD track and an AC3 track, you have all of the encoded audio data you need, you just need to remux/repack the audio frames into the correct format.
That's what I understand they're working on for tsMuxer, and there is no other tool I've found that can do it.
eac3to can remux a TrueHD stream into a THD+AC3 stream, but has to encode a new AC3 stream to do it. It doesn't support remuxing an existing AC3 stream.
The mlp tool for accurately/losslessly editing THD streams has an open issue requesting support, but there's no activity on it.
I just did this for Top Gun: Maverick, and the TrueHD track is now significantly louder than the lossy AC3 track. Is that normal, or is it doubling up by adding a track onto a track? I don't want any clipping or harsh sounds from it if so.
I didn't get to play it super loud to determine this yet, by the way. I was just curious if this is normal when this happens, since I can't mux it just as a THD with the AC3 track.
EDIT: Better yet, I muxed the original AC3 track with the THD+AC3 track. Should I have not done that? Is that why it is a louder volume? Should I leave the AC3 track completely out and it'll still be fine?