ADMIN NOTE: moved the previous two posts from here: https://fanrestore.com/thread-3435.html because they contain interesting notes about Cinema DTS (and were offtopic there, too... )

(2020-10-03, 03:49 AM)pipefan413 Wrote: ... Or, even better, use a lossless compression format instead to completely eradicate even the theoretical possibility of perceptual degradation, as he's done. Not the most storage efficient, but preferable from a preservation perspective. I dunno any other reason you'd want to deliberately do lossy -> lossy transcoding apart from file size and the difference is arguably not worth the cost.

Nonetheless, thank you for the fairly tidy summary of the compression methods used by DTS formats, it's nice seeing that put fairly succinctly in one place.

Agree; actually CinemaDTS->DTS-HD MA is the best way to get BD/UHD-BD compatibility and retain maximum fidelity, while converting to "mere" DTS 1509kbps would get lower file size while retaining quite good quality and even DVD compatibility (in the remote chance it would be useful).

I don't see the comparison about MPEG (I guess MP3) to FLAC, which is a lossy->lossless conversion; as there is no format AFAIK that reads natively APT-X100, it must be converted first to PCM (WAV); converting that to FLAC will only shrink the file size, leaving the converted PCM untouched.

(2020-10-03, 03:02 AM)WiLDCAT Wrote: 1990s theatrical DTS based used the original Apt-X 100 coding scheme which was a lossy fixed 4:1 compression ratio. It is NOT lossless. So transcoding these tracks to lossless Master Audio doesn't make sense. It's akin to encoding MPEG Audio to FLAC.

Infact the consumer Coherent Acoustics variant is far superior than the original Apt-X DTS and at full rate 1509kbp/s it is far superior in fidelity to 90s theatrical DTS and uses more sampling bands as well.

DTS went lossless around '04-'05 theatrically in favor of a lossless scheme based on Coherent Acoustics that eventually became DTS-HD MA yet retained the DTS bar code on the edge of the film strip so they were still able to offer discrete digital on special 70mm prints for example which Dolby could not do with the SR-D large barcode prints, only magnetic 6-Track Dolby Stereo.

So for all intents and purposes the closest consumer format transfer/container for original Apt-X theatrical DTS would be Coherent Acoustics 5.1 with a bitrate of either 960kbp/s or 1152kbp/s. But since original theatrical DTS and Coherent Acoustics are both lossy going full rate 1509kbp/s to prevent audible generation loss is ideal.

This makes no sense. Coherent Acoustics is a completely different codec to APT-X100 and is lossy in a different way, so you're essentially layering two lossy processes over each other. Encoding lossless is the only thing that makes sense to prevent any further loss, since sadly it's not possible to include the raw APT-X100 data in an mkv or similar.

I want to add that FLAC happens to compress Cinema DTS (APT-X100) data very very well, so well in fact that it often is close to the size you would have with the lossy Coherent Acoustics, or in some cases maybe even smaller.

You can argue that the loss cannot be heard, but we're talking restoration and preservation here. What if someone down the line wants to process the data further and cannot find the original APT-X100 data? Then he has to work with double-lossy-encoded.

Among encoders in general it is looked down upon to encode lossy to lossy, for what it's worth.

If Hollywood aims to preserve audio fidelity by including lossless audio on Blu Rays, why shouldn't we aim to preserve audio fidelity in a similar way? "It's already imperfect, so it can't hurt making it even worse" is not a good argument at all in my eyes. In fact, I'd argue the reverse and say the *only* justification for ever doing a lossy audio encode is when the source is lossless, since you end up with only a single pass of encoding.

(2020-10-03, 10:47 PM)TomArrow Wrote: This makes no sense. Coherent Acoustics is a completely different codec to APT-X100 and is lossy in a different way, so you're essentially layering two lossy processes over each other. Encoding lossless is the only thing that makes sense to prevent any further loss, since sadly it's not possible to include the raw APT-X100 data in an mkv or similar.

I want to add that FLAC happens to compress Cinema DTS (APT-X100) data very very well, so well in fact that it often is close to the size you would have with the lossy Coherent Acoustics, or in some cases maybe even smaller.

You can argue that the loss cannot be heard, but we're talking restoration and preservation here. What if someone down the line wants to process the data further and cannot find the original APT-X100 data? Then he has to work with double-lossy-encoded.

Among encoders in general it is looked down upon to encode lossy to lossy, for what it's worth.

If Hollywood aims to preserve audio fidelity by including lossless audio on Blu Rays, why shouldn't we aim to preserve audio fidelity in a similar way? "It's already imperfect, so it can't hurt making it even worse" is not a good argument at all in my eyes. In fact, I'd argue the reverse and say the *only* justification for ever doing a lossy audio encode is when the source is lossless, since you end up with only a single pass of encoding.

thank u sir

If Hollywood cared about audio fidelity it would give us the original mixes.

FWIW I have used dcaenc in the past for my Cinema DTS projects because it works on my system and offers blu ray compliance for those who still burn to disc, as well as being freely available. I generally include a FLAC file as well for the golden ears and those who get compatibility problems with the DTS. FLAC is basically real time rar archived PCM which is why it compresses so well

(2020-10-03, 11:34 PM)zoidberg Wrote: If Hollywood cared about audio fidelity it would give us the original mixes.

FWIW I have used dcaenc in the past for my Cinema DTS projects because it works on my system and offers blu ray compliance for those who still burn to disc, as well as being freely available. I generally include a FLAC file as well for the golden ears and those who get compatibility problems with the DTS. FLAC is basically real time rar archived PCM which is why it compresses so well

The interesting thing is that FLAC seems to compress Cinema DTS sourced data a lot better than just normal lossless audio from a Blu Ray. I've gotten bitrates around 1500 kbps with FLAC I think, which for 6 channels in a lossless codec is pretty impressive. Maybe the particular lossiness of Cinema DTS is easy to analyze for FLAC and it is able to simply ditch the data that had been ditched in the first place.

Frankly, I would be curious to know results of blind tests of Cinema DTS converted to DTS-HD MA and DTS 1509kbps... pretty sure nobody would hear the difference, even if agree with Tom about the fact the former would be useful for further processing, even if I personally do not care too much - I mean, if John Doe wants to convert my hard work to AAC, let's do it from DTS 1509kbps, but if a member here would like to get it to for a valuable project, I have no problems to send the lossless version...

(2020-10-04, 12:06 AM)spoRv Wrote: Frankly, I would be curious to know results of blind tests of Cinema DTS converted to DTS-HD MA and DTS 1509kbps... pretty sure nobody would hear the difference, even if agree with Tom about the fact the former would be useful for further processing, even if I personally do not care too much - I mean, if John Doe wants to convert my hard work to AAC, let's do it from DTS 1509kbps, but if a member here would like to get it to for a valuable project, I have no problems to send the lossless version...

Yeah, I say this a lot: I don't use lossless codecs because I have any illusions about being able to hear the difference, I use them for preservation/archival. My entire CD collection is ripped to FLAC on hard drives partly because I can then transcode to Ogg Vorbis for use on mobile devices with limited storage, but I would be insane to *only* have them as Vorbis. And MP3 is inefficient at transparent bitrates for me. Same principle here: yeah I could definitely listen to a transcoded 1509 kbps DTS -> 1509 kpbs DTS file and be happy telling you that it might be lossless, but I still wouldn't want that to be my only copy of that audio. You never know what you might want to revisit later or convert to another format because something else becomes the dominant thing several years down the line. I was slightly surprised at the prevalence of DTS-HD MA on Blu-ray because DVD had been so full of Dolby Digital stuff for so long.

This test showed that eac3@448kbps is pretty near full DTS.  At 640kbps, it's not far from lossless for 5.1, so it's another option that's worth considering if space saving is an issue.

Sure, I'll never use lossy format as archive, but only as a release format - maybe it's better to give, let's say 3+GB to video, spared using DTS instead DTS-HD MA... but it's mainly me, that I continue to want to release tracks in five different languages!

About compression in general (surround 5.1): I think AC-3@640 is more or less equal to DTS@1509, still the latter can be used "as is" on DVD - for what it worth; I'd never use DTS@768 for its high frequency loss (that I would never hear, by the way, but I would always know it would be not "up to the task") and I'd not go under AC-3@448, unless using LD AC-3@320kbps "as is"!

While browsing eBay I came across this:

What exactly is it? Is it just a stereo mix in DTS format? Is it matrixed or straight stereo? Why would a theater install a DTS system if they can only do stereo, especially since the print already contains a Dolby Stereo Mix?