Fighting a pesky export problem on a 23.976 1080P project. I have a completely DNX-175X timeline with safe color rendered to DNX-175X on upper track. I have 12 audio stems. I have exported the entire one hour show successfully and it has been QC'd out of house and passed. Now I'm pulling a 7 second sequence of two shots from the above sequence. I do my QT Ref export to maintain all the audio tracks as discrete tracks and everything is perfect until I ama link back and play it down. As soon as it hits the second shot the Avid hangs with spinning beach ball. I'm on SNDX 6.5.4.7 Mac OS 10.8.5. I then make a mixdown and put it on a top track and do the same exports but still have the same problem. I then remove all but the mixdown track and finally I can ama link and play the whole clip without a hang.
Okay I know mixdowns are the cure for whatever ails an export but here is something curious. My video mixdown is DNX_175X but when I ama link back to the resulting saved as self contained .mov Avid sees the file as Avid DNxHD not DNxHD 175 X (HD1080p) and plays the short 7 second clip back stuttery. All the other .movs that would hang did read as DNX-175X when ama linked. If I analyze the QT Ref file in Media Info I get:
MPEG-4 (QuickTime): 922 KiB, 46mn 30s
1 Video stream: VC-3 (DNxHD)
12 Audio streams: PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM /
1 Video stream: VC-3 (DNxHD)
12 Audio streams: PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM /
If I analyze the resulting QT .mov saved as I get:
MPEG-4 (QuickTime) (DNxHD 175x): 169 MiB, 7s 466ms
1 Video stream: VC-3 (DNxHD)
12 Audio streams: PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM
1 Video stream: VC-3 (DNxHD)
12 Audio streams: PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM / PCM
Given the video essence has to be DNX-175X based on the video mixdown resolution why does avid register the ama link as Avid DNxHD Codec and playback stuttery when all the other exports without the mixdown and even with the mixdown but keeping the other original media tracks register as DNxHD 175 X (HD1080p) and playback without stuttering, that is until they hang at the second shot?
To summarize the video mixdown only sequence does eliminate the hang on the second shot but yield stuttery playback when ama linked while the virgin and mixdown plus original sequences hang on the second shot but do play clean when ama linked. All the files play fine in QT Pro7 without issue it's just the ama link that is curious. It's also frustrating that I can export the entire show without issue but not just a small section. This is one time I'm doing the mixdown dance and it seems to have a downside. I've always considered an ama link back to a file and a playback to be a decent representation of the files validity but not a complete guaranty of compatibility down the line. I suppose the most trusted approach of exporting the mixdown sequence directly from Avid and skipping the QT Ref might resolve this but with 6.5.4.7 the interleaved audio channels is a problem for the delivery so I am force into the QT ref dance. I understand the later Ver. 8 Avids are able to export discrete audio direct out but I'm not in a position to run that version at this facility.
Can anyone suggest why Avid would see what is clearly Avid DNX 175X video essence as just Avid DNxHD and play back stuttery on an ama link?
John Moore Barking Trout Productions Studio City, CA bigfish@pacbell.net
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Posted by: John Moore <bigfish@pacbell.net>
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this is the Avid-L2
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