Integrity Check Failures

[Martin McCaffery]

Solaria One. GDC_SR1000. NetGear NAS
I've taken to running verification integrity checks after ingesting film. Immediate Verify rather than Quick. I'm not really sure of what it means when verifications fail, or as they say, have an Exception.
Loaded a film today that had to be downloaded via FileMail. It ingested fine with no errors, but the verification took about twice as long as the ingest, and when it finished presented an exception: "Picture file Integrity Checking Failed."
This feature only had three files Picture, Sound, and CPL. I'm used to way more files being present. Nonetheless, the feature loaded and is now playing [no KDM needed]. It has about an hour and 15mins to go. This is just a test, no audience.
My question is, does running Verify actually inform me of anything other than a catastrophic error? Are there things like the problem at the end of last year that show up as an exception, but don't effect my projector/server. Is it worth running Verify?

[Jim Cassedy]

WoW! I've never seen a DCP with fewer than 6 files. I'd like to know how they did that!

[Ryan Gallagher]

That error relating to the picture file makes me think the checksum did not match. It may play, but play all the way through is TBD.

But if it didn't throw that exception upon initial ingest i'm confused, unless GDC does not do checksum comparisons unless you ask it to via manual verify?

Edit: if it was related to last year's Y2K24 bug the exception would be related to the CPL signature, "Signature Invalid" etc, not the picture file integrity.

[Ryan Gallagher]

Aside: Was the whole DCP delivered as one zip file?... if not, we find that many file-sharing tools mangle the download process, dropbox and google-drive are especially egregious. It's usually just some file-names you have to manually repair, but getting this as packaged archive of some kind is much more reliable.

I'd put my money on some bits having gone missing in the filemail download process (or the other end's upload process). Re-download Re-ingest is the only way to know.

[Ryan Gallagher]

You can also manually view the ASSETMAP xml and verify that you have all the files it lists. Doesn't help with checksum mismatches but if you were missing a reel of video you could tell.

[Harold Hallikainen]

WoW! I've never seen a DCP with fewer than 6 files. I'd like to know how they did that!

Most DCPs have a file per reel, but some put all the image in one file and sound in another. If there are captions or subtitles, some equipment may have problems with large files. Some CPLs do break the composition into reels that all are in the same file using EntryPoint and Duration to identify the reels within the file.

[Martin McCaffery]

The film played all the way through without stopping. I didn't sit through it, so don' know if there was some weird glitches, but one would suspect they would stop the show.

[Ryan Gallagher]

The film played all the way through without stopping. I didn't sit through it, so don' know if there was some weird glitches, but one would suspect they would stop the show.

Good outcome. In future when downloads are suspect you can also use "DCP-o-matic Player" to separately run a verify. It's under the "Tools" menu. It may give you a more verbose or precise error.

[Frank Cox]

If you're selling tickets to a show and especially when you're unsure if it's actually ok, why wouldn't you sit through it to check it out first?

If the picture glitches in the middle of the show, I wouldn't want the first time I found out about it to be when a paying audience was sitting there watching it.

I sit in the auditorium and watch every movie that I play here before I play it for the public. The only exception was one of the Hunger Games movies where it didn't arrive until about one hour before the first scheduled showtime.

[Martin McCaffery]

Given that I've had films glitch after the first run through, I don't have a lot of faith in digital as it is.

Ideally, shouldn't there be software that will confirm everything?

Now that the keys only activate on the day of the show or the night before, I don't always have time for a full view. I try to make sure everything starts playing the way I want it, check out about three places in the movie and pray for the best. Getting QC keys is an option, but they want to set up certain hours and I don't usually have that flexible a schedule.

The film in question isn't playing until August, and no keys, so I could check it out this week. The paranoid in me wants to delete it and re ingest, just to be safe. Going to give DCP o Matic Player a try, just to see.
Just had to download another film today. Something to look forward to.

[Frank Cox]

Given that I've had films glitch after the first run through, I don't have a lot of faith in digital as it is.

True, but I figure it's worth reducing the chance of an issue as much as possible.

Since I had one movie that actually played in the wrong order (the end of the movie came before the middle) just cranking 'er up and walking out of the room and calling it a test screening if it didn't stop the playback prematurely isn't the answer either. I figure that I've pretty much got to watch it from start to finish to be reasonably assured that I've got what I think I've got.

[Antti Näyhä]

A valid and complete DCP should have a minimum of six files: video file, audio file, Assetmap, Volindex, CPL and PKL.

I know that many servers will happily ingest a DCP without an Assetmap and/or a Volindex. These files contain nothing crucial, and can be regenerated by the server upon ingest if necessary.

It was news to me, but apparently the GDC will even accept a DCP without a PKL. In this case the CPL file cannot be hash-checked, since the corresponding checksum would be in the PKL.

[James Gardiner]

From memory, a CRC verification IS REQUIRED under the DCI specification before you should be able to play the assets. Though this was flexible due to the later requirement to be able to do emergency playback of a attached drive. But technically, when you ingest content, the system will ALWAYS do a verification that byte for byte it is exactly what it should be and has not been altered in any way. (Security security security)
ZIPing a DCP is common and not a bad idea if your not sure of the type of file copy/transfer technologies being used between where the DCP is created and where it ends up. Its very common for some pathsways to add extra padding bits onto the end of a file, which can break the CRC. So unless you know the transfer system being used can maintain the file integrity, using a ZIP around the DCP is a good path and very common in preshow DCPs. (Ads etc)

Yes, many Players can ingest a DCP without all files needed. CPL/PKL/MXFs for the target CPL only need to be present. Its all it really needs. The rest are for cross disk DCPs (Never really happened) or for multiple DCPs.
For example, it's how you can ingest a single CPL from a multi CPL DCP into a server and then ingest it from server to server, without the need for the original DCP. (From experience... some of the players make dummy extra files itself, to trick other player into seeing everything it needs to ingest. for example, ftp into Dolby under manager, got to /assets/UUID-OF-CPL and you will find PKL and ASSETMAPS generated by the player that is only covering what is needed for the CPL in question.)

In terms of GDC working without a PKL. not sure whats happening there, but does not sound right to me. Maybe it relys on the fact the key data in the CPL is digitally signed and relys on that for authenticity.
Needs some one like John Hurst to answer that one.