Film-Tech Forum ARCHIVE: Atmos in Non-Atmos Theater

This is topic Atmos in Non-Atmos Theater in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Bradley J Sime (Member # 9423) on 02-19-2018, 12:25 PM:

What will it sound like? We have a screening of Blade Runner 2049 tomorrow and they sent us the wrong drive, three atmos versions of the film...we aren't an atmos theater. Presentable?

Posted by Carsten Kurz (Member # 5396) on 02-19-2018, 12:51 PM:

I don't know if all servers do that, but ours simply plays the normal 5.1/7.1 soundtrack, and just leaves out the ATMOS data. A while ago, a StarWars or Rogue One trailer circulated in ATMOS format, and we were able to play this normally on both our Sony and Barco ICMP. I then got interested and sourced an ATMOS DCP for which we had received a KDM inadvertently - it, two, played in 5.1/7.1 on our Sony and Barco. There is a mechanism in ATMOS that allows to fall back onto the normal 5.1/7.1 mix that usually comes with the ATMOS DCP, in case something fails for the ATMOS content. I didn't know this would also work for systems that had no ATMOS support at all. At the time I tried this, our Sony was not even 'ATMOS aware' (no ATMOS support in the software).
But, that doesn't necessarily means it works on all servers, or under all software revisions. Keep in mind, you definitly need the KDM for the ATMOS CPL. A KDM for the non-Atmos 5.1 or 7.1 CPL/DCP will NOT allow you to play the ATMOS DCP at all.

- Carsten

Posted by Bradley J Sime (Member # 9423) on 02-19-2018, 12:53 PM:

Yeah, that's what I figured. Yep, we have the right key (had to call technicolor for it this morning). Good to know!

Thanks, Carsten.

Posted by Carsten Kurz (Member # 5396) on 02-19-2018, 01:04 PM:

What server are you using? Please report back wether it actually worked!

I remember I ftp'ed into our Sony during those test and found the actual ATMOS aux data mxf file in it's DCP directory. So, it was ingested, but just wasn't used during playout. AUX data is part of the SMPTE DCP definition, not an ATMOS specific thing. So the only thing the Sony did was following a proper SMPTE ingest and didn't care wether the file was actually useful or not.

- Carsten

Posted by Alexandre Pereira (Member # 9295) on 02-19-2018, 01:13 PM:

A while back I received the Atmos version of IT! The Atmos version DCP was the only file on the drive. Some mix up at Deluxe. There was no time to exchange the drive so Deluxe sent the key for the drive. Worked fine both on the Dolby DSS 200 and the Sony LMT-300 down converting to 5.1.

Posted by Carsten Kurz (Member # 5396) on 02-19-2018, 01:31 PM:

Actually it's no conversion or downmix (that would need the server to actually understand and decrypt ATMOS), but all the ATMOS audio is in a fully separate file, while the DCP also contains a standard 5.1 or 7.1 audio file, that (should) contain the same audio as the non-ATMOS 5.1 or 7.1 DCPs.
When the ATMOS part is not playable, the standard 5.1 or 7.1 audio is played as in ordinary DCPs, and the ATMOS audio isn't even touched.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 02-20-2018, 03:26 AM:

Actually, all servers supporting one of the later revisions of the SMTPE DCPs should be able to play Atmos DCPs. To conform to specs, a valid 5.1 or 7.1 downmix is still required to be present inside the DCP and the server is supposed to ignore the assets in the CPL it doesn't support.

I guess the reason for studios/distributors to still do split-releases is to maximize compatibility.

Unfortunately, the idea of a single-inventory distribution format got lost somewhere in translation. [Wink]

Posted by Monte L Fullmer (Member # 2797) on 02-20-2018, 02:27 PM:

with SMPTE content, usually the ATMOS is a VF file that is attached to the default 5.1 OV content during the ingest.

Disney started with this one.

Posted by Bradley J Sime (Member # 9423) on 02-21-2018, 07:58 PM:

Christie Digital Cinema Server. It worked fine. Sounded the same as the 5.1 file we received a month or so back. Or, if different, basically indistinguishable.

Posted by Michal Matys (Member # 8614) on 02-23-2018, 03:03 AM:

Atmos actually runs via network, so everytime you play atmos there is a 5.1/7.1 running over AES as well as backup if atmos fails for some reason, so you should be able to play any atmos dcp in 5.1

Posted by Carsten Kurz (Member # 5396) on 02-23-2018, 11:57 AM:

That's fairly obvious if you are running an ATMOS feature on an ATMOS enabled system. It is not so obvious when you try to do this on a plain-vanilla projection system with no explicit ATMOS support. I know one media block that used to fail on this.

One could also question that behaviour, because usually a CPL should play only if all content of that CPL has been properly ingested and the integrity is not compromised. On an ATMOS enabled system, you could allow fallback to 5.1/7.1 for good reasons, but not in general. There must be something about SMPTE AUX data that allows this.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 02-24-2018, 03:59 AM:

quote: Carsten Kurz
One could also question that behaviour, because usually a CPL should play only if all content of that CPL has been properly ingested and the integrity is not compromised. On an ATMOS enabled system, you could allow fallback to 5.1/7.1 for good reasons, but not in general. There must be something about SMPTE AUX data that allows this.

If I remember it correctly, this is not entirely complete. It should fail if it cannot ingest the components of the CPL it is supposed to understand. But the idea of the SMTPE DCP format is to be extensible and both backward compatible. Backward compatibility can only be achieved if systems are allowed to ignore parts of the CPL they don't understand or don't have the necessary means to handle for.

They could, potentially, still check the integrity of the non-handle-able asset based on the checksum and fail if this doesn't match up.