I have a number of 1080p/59.94 files recorded during one session on a Blackmagic Mini as DNxHD 90.  Some link as "DVxHD 90 (HD1080p)" and others as "Avid DNx Codec", both using the QuickTime plug-in.  The DNxHD 90 linked files play back smoothly while the Avid DNx identified files stutter. 

Why are they not all seen as one or the other.  Can I change the designation of the link?

I'm using a Windows 7 PC running MC2018.10.

Does the console give you any clues when you first do the link or when you play them? AFAIK you can't change the designation. I wish you could.

When I play a clip tagged as Avid DNx Codec I usually get:

[QuickTime Plug-In] The movie has variable sample duration.QuickTime: Unknown error

plus multiple lines of just:

QuickTime: Unknown error

on the console.  I haven't seen it ever when playing clips tagged as DNxHD 90.  Very strange, as these clips were recorded one after the other in the space of 6 hours. 

This was a casting call and the clips, each trimmed on a separate timelime, are exporting with no issues.

Does playback stutter on all settings of the Video Quality Menu? I have had the same problem with ProRes when Avid Links the generic codec rather than the fully supported one.

Changing the Video Quality setting doesn't appear to change the playback issues.  Some clips  stutter while others, the video slows while the audio plays normally.  Pause/release resets the audio, but it pull ahead again. 

One sometimes doesn't show any video, but it transcoded fine and was usable.

Very strange.

Try linking then exporting it out as Same As Source (use Avid codec).

Relink. Curious if that fixes it.

Use Mediainfo to examine the files and see what the difference is. There must be a difference for Avid to treat them differently.

First thing I tried before posting.  MediaInfo shows them as identical.  That's what has me flummoxed.

MediaInfo is a very helpful tool but it only goes so deep into QuickTime. It looks like Avid is finding a diffence in the BMD files.

It looks to me like Avid has made many changes to QuickTime Linking as new versions are released. Back around MC8.8x they started working to remove dependencies on QuickTime libraries. I don't have experience with the BMD files but work with large numbers of ProRes files made by different vendors. If Avid finds something it is unsure of it assign a generic codec and playback will stutter just as these BMD files are doing. I have a ProRes encoder we use daily that use to Link fine in MC8.6.5 but has not worked correctly since before 2018.x. In our shared environment I can first Link the files in 8.6.5 and then open the project in 2018.12 and they play fine at full quallity Green10. If I re-Link in 2018.12 the codec goes back to generic and playback will stutter like crazy. Go figure... It would be great if when Avid panics due to something in a file it doesn't understand it would let me select a codec and see if it works. With RickP's BMD files and my ProRes files, they Transcode fine.

Dom Q. Silverio:

Try linking then exporting it out as Same As Source (use Avid codec).

 

Relink. Curious if that fixes it.

 

This is an interesting idea. I don't have the BMD files but I tried it with ProRes (on MAC). If Avid has assigned the generic codec (Link in 2018.12) it will not export SAS, saying there are no clips to export that way. If the supported codec is assigned (Linked in 8.6.5 first) it will export SAS just fine from 2018.12. The SAS export then Links in 2018.12 correctly!

Thanks Dom!

Finally got the time to try an export "Same As Source".  Pretty much the same as DonE's results - the "Avid DNx Codec" ID'd files will not export claiming the resolutions were not supported. 

The Media Composer's Get Info window on one of these files shows "unknown" Chroma Subsampling rather than the 4:2:2 of those recognized as DNxHD90.

Pat - whilst not strictly a DNX issue, I wonder if my experience might shed some light...

I recently posted an issue "ProRes not able to consolidate" - due to "foreign compression type". Other symptoms include: no timecode displaying on audio tracks, odd fps, displays as "ProRes" (as opposed to "Apple ProRes"). This has huge implications for sequence consolidating for delivery to grading and audio mix houses.

My workaround is to cut the clip into and Avid timeline (with the same timecode as the clip) and export SAS, direct audio. The exported clip links fine, with timecoded audio, displays as "Apple ProRes HQ HD 1080i".

What is weird is that by using the MediaInfo tool, the original (dodgy, according to my Avid) clips are described as:

Format: Quicktime, Format/Info: Original Apple Specification.

Whereas the clips that I export SAS (and can then re-link and consolidate ino problem) are described as:

Format: MPEG-4, Format Profile: Quicktime.

I have checked with my copy of MC 2018 different partition, same OS) and get the same issues. I have edited ProRes HQ rushes and other ProRes HQ xfers for years with no issues and (since Avid v.7) been able to link, consolidate and export with no problems.

Given that the original files were created on a mac in a post house using FCP7 and I'm editing on a mac OS 10.12.6, with Avid 8.9.1 (no Windows or third party "fake PRoRes" involved, I wonder if Avid's Quicktime AMA plugin might have altered in recent versions?

Oh we know the Avid QuickTime AMA plugin is undergoing signidicant changes as they gear up to not being reliant on the old legacy QT engine.

And that will have unexpected implications. Best to raise it as a support issue and ensure engineering know the issue exists.

Well, this sort of fell off my radar after the project was completed.  But, the same senerio came up last week, with the same issues.  And, worse.  My first pass was just like the original project - correctly ID'd clips play back fine, "Avid DNx Codec" stutter and lag.  Tweaking some of my timelines a day later, and the clips do not play.  Then, the PC freezes and reboots.  Repeatedly.

I also tried setting the Mini to record DNxHD 145 (DNxHD 290 for 59.94).  Same problem.

I will try the Blackmagic forums to see if there is any mention of this.

I would try opening the files in Resolve and see if there is any discernable difference in how Resolve sees them vs MC. Also you could try the program GSpot to investigate the files.

Good luck!