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  • Mon, Apr 11 2016 4:34 AM

    • carlgmi
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    Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    As per my post on the MAC forum where a user seems to have bumped into this problem (post copied below):

    The project is a 1080 50i PAL project that, to date, has vision from our P2 cameras in it.  Enter our new DVX 200 4K.  We have this set up for UHD 50p on internal cards (so 4:2:0 or 4:0:2, cant remember).  Bringing in the vision:

    AMA link to folder
    Transcode to 1080 50i - no need to hog RAID space when it isn't needed.  See below:

    mmmmm, nice... NOT!

    Then tried setting the project to UHD 25p and transcoding to DNxHR 25p (no 50p option - the project is 50i so 50p is greyed out)

    YUK!  These stills show both fileds - looks even worse when paused but understandable.  So we played with various frame flex options and the results were the same.

    Next - don't use transcode, use "import":

    same result as the "transcode" to DNxHR HQ 25p - better than the "transcode" to DNxHD 50i but still not good.

    Finally, use "import" to bring it in.  Project is set to 1080 50i during this step:

    Yay, we have a winner, nice smooth lines.  Incidentally, using Adobe Prelude/Media Encoder to transcode the 4K to DNxHD 50i also produces this nice clean result.

    So I think the "transcode" engine is broken and not doing a good job.  Naturally I want to use "AMA Link/Transcode" as it is twice as fast bringing the vision in using the "Import" option.  A 30" clip takes under a minute using this method compared to 2 mins for import... (btw the Dual Xeon is on this years shopping list..)

    We have fiddled with the settings available on the Transcode dialogue, trying different DNxHD settings, 10bit, 185 etc and the results are always the same.  I am keen to hear any thoughts others have had with this.  Moving forward, some of our projects will be native 4K 50p but lots wont be and we'd rather collect vision at 4K for future projects than set the camera to its 1080 settings.

    Here is the earlier email: 

    Hi all - I've just run headlong into the 4K 50p > 1080 50i aliasing issue with vision shot on a DVX200.  Jaggy lines when the vision is transcoded down to 1080i.

    #1
    Project is 1080 50i (historic project with P2 HD in it)
    AMA link to 4K 50p external HDD
    horizontal fine lines are jaggy at this AMA linked stage
    Transcode to DNxHD 120 50i internal RAID
    Jaggy lines

    #2
    As above but tick Frameflex button so the vision reports as 1080 after transcode - no change, jaggy lines still

    #3
    Create a 1080 25p project
    AMA link and transcode - jaggies are gone
    Swap to 1080 50i and bring in P2 vision then
    All fine too

    #4
    Use Adobe Media Encoder to take the 4K 50p and turn it into 1080 50i - perfect
    But this adds a transcode step outside of Avid and why does Adobe's transcode engine get this right and Avid's appears broken?

    Can anyone else confirm?  It is a real pain.

    PS monitoring on matrox/TV combo, confirmed on output DNxHD mov file export so it is not monitoring as far as I can tell - especially as it can look fine if 25p is selected at the 1080 stage..

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

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  • Tue, Apr 12 2016 3:49 AM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Further frustration!

    Yes, the jaggy lines are gone using the import method... but... in converting the frame rate I now have some wierd playback effect where it "looks" like it drops a frame like it is performing a pull down??

    At this point we have decided several things:
    1 - For a 50i project where we want to use 50p 4K from the DVX we will let Adobe Prelude/Media Encoder to do the transcode.  Results are perfect.
    2 -  For new 1080 projects where we will use only progressive source (25p or 50p 4K or HD) we will let Avid do the transcode as results are fine
    3 - To maintain highest quality we will set projects at UHD 50p and transcode to DNxHR SQ

    It is frustrating to say the least.  We have spend 1.5 days trying different combos for a mixed format workflow and so far, Adobe is the savior.  I desperately want to avoid an additional step in the ingestion process but it seems like it isn't possible with the Avid at this stage.  I can't find a pattern to the "drop frame" look - the "stuttering" seems random and not some multiple of 24, 25 or 30 frames within the clip (though more investigation is needed).

    The stuttering happens at exactly the same frame each time I transcode the same clip in different settings (you can step through the clip and see the frame where the movement of a subject is 50% of the movement in the frames either side - like it has picked the wrong pair of frames to convert to 1... does that make sense??).  Is it something to do with the camera's "long gop" H264 recording.  I seriously have run out of crazy ideas to try!

    I'll bump this from time to time to see if anyone else comes across it...

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Tue, Apr 12 2016 4:54 AM In reply to

    • mjolnarn
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    What Avid version Carl , I might have seen " something "

    Mac: 17" Macbook Pro i7 2,66 ghz with 8Gb Ram, 500gb 7200rpm drive___ PC_NEW Win10 Pro Mbo Asus Rampage IV Black CPU Ivy Bridge-E 4960X ( = 12 x 4... [view my complete system specs]

    Tomas 

     

  • Tue, Apr 12 2016 5:30 AM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    8.5.0 is the version...  thanks Tomas!  I am happy with my workaround but disappointed that I have to use it - especially as my co-editor points at Premiere and says "see, swap now, save yourself all this hassel"!

    Also surprised that others aren't seeing this.  We know it isn't a monitoring issues through exports etc, the problem is "burnt in" during the transcode or import.

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Tue, Apr 12 2016 5:47 AM In reply to

    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    carlgmi:
    Also surprised that others aren't seeing this.
    Do you have a small file you can dropbox for testing?

  • Tue, Apr 12 2016 5:48 AM In reply to

    • mjolnarn
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Have you tried to ama link and render the motion adapter directly on the linked clip

    Mac: 17" Macbook Pro i7 2,66 ghz with 8Gb Ram, 500gb 7200rpm drive___ PC_NEW Win10 Pro Mbo Asus Rampage IV Black CPU Ivy Bridge-E 4960X ( = 12 x 4... [view my complete system specs]

    Tomas 

     

  • Tue, Apr 12 2016 6:08 AM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Can you explain?

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Tue, Apr 12 2016 6:34 AM In reply to

    • mjolnarn
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    When you ama link the 4k 50p clip to that 50i project you will get adapters auto added, test with differnt settings for the motion adapter , you might want to promote it , maybe fluidmotion draft is something to test , then render directly to dnx and take a look

    Mac: 17" Macbook Pro i7 2,66 ghz with 8Gb Ram, 500gb 7200rpm drive___ PC_NEW Win10 Pro Mbo Asus Rampage IV Black CPU Ivy Bridge-E 4960X ( = 12 x 4... [view my complete system specs]

    Tomas 

     

  • Tue, Apr 12 2016 8:08 AM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    OK, will test tomorrow - but where do I see these "motion adapters"?  In the Source settings?  Or is it in general settings?  Excuse my ignorance!

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Tue, Apr 12 2016 8:16 AM In reply to

    • Joachim Claus
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    carlgmi:

    At this point we have decided several things:
    1 - For a 50i project where we want to use 50p 4K from the DVX we will let Adobe Prelude/Media Encoder to do the transcode.  Results are perfect.
    2 -  For new 1080 projects where we will use only progressive source (25p or 50p 4K or HD) we will let Avid do the transcode as results are fine
    3 - To maintain highest quality we will set projects at UHD 50p and transcode to DNxHR SQ

    It is frustrating to say the least.

    Carl,

    I was in a comparable situation when I started first edits with video recorded by Panasonic AG-DVX200. My medium term format is UHD 50p. Unfortunately, UHD-BluRay players are not yet available (hopefully coming soon). In the meantime I create BluRays with 1080/50p resolution. With this said, i experimented a lot to find a nice workflow with Avid MC, to get a fluid editing, while maintaining the desired format options. After a number of tests with different options, I ended with the following workflow:

    1. Create an UHDp50 project.
    2. Link to media.
    3. Switch project to 1080p50 (leave editing at 25 fps)
    4. Transcode to DNxHD 185 (format 1080p/50).
    5. Edit the video in 1080p format.
    6. Export final project with QT-Reference file for subsequent BD-authoring for 1080p BluRay.
    7. Switch project back to UHD/50p
    8. Transcode linked media (from step 2) to DNxHR SQ.
    9. Duplicate final sequence(s) from step 5/6.
    10. Relink duplicated sequence to UHD media (parameters: Relink by Tape name or source file name, Video parameters: specific resolution, Relink Quality: is equal to.
    11. The relink results in a new sequence, with video clips relinked to UHD video clips.
    12. Render and export as QT-Reference for UHD-BD authoring, and conversion to MP4 (UHD) for direct display on my UHD-TV.

    Regards,

    Joachim

     

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    Joachim Claus

  • Tue, Apr 12 2016 8:50 AM In reply to

    • mjolnarn
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    carlgmi:

    OK, will test tomorrow - but where do I see these "motion adapters"?  In the Source settings?  Or is it in general settings?  Excuse my ignorance!

    You should see a " T " on the clip once it placed on your sequense and when opening up the motion editor you will be able to both promote and control / adjust the render settings

    Mac: 17" Macbook Pro i7 2,66 ghz with 8Gb Ram, 500gb 7200rpm drive___ PC_NEW Win10 Pro Mbo Asus Rampage IV Black CPU Ivy Bridge-E 4960X ( = 12 x 4... [view my complete system specs]

    Tomas 

     

  • Tue, Apr 12 2016 12:32 PM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Hi Tomas

    OK,but that assumes I dump the clips, before transcoding, into a timeline then adjusting each clip before rendering? Correct? What if the media is scattered on several HDDs and I want to transcode the vision at the clip/bin level before it goes anywhere near a sequence so none of the vision remains AMA linked?  Am I understanding correctly?

    Will look first thing tomorrow Australain time - dark here now!

    Thanks for the help!

    Carl

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Tue, Apr 12 2016 12:36 PM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Danke sehr Joachim, aber ich hab 50i und 50p - sie haben nur "p" 25p und 50p.  Diese "mixed formats" sind sehr schwer - aber mit Adobe Transcode, alles gut, alles richtig in Avid!

    Mein Deutsch ist nicht sehr gut aber - hier ich kann ein bisschen schreiben fur sie! :)

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Tue, Apr 12 2016 12:46 PM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Yes Andrew - it is big as it is a 26" clip. I'll PM you with a link once our wonderful non NBN internet manages to upload it. Thanks!

    Carl

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

  • Wed, Apr 13 2016 1:25 AM In reply to

    • carlgmi
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    Re: Bad aliasing when transcoding 4K 50p to DNxHD120 50i

    Hi Tomas

    mjolnarn:

    You should see a " T " on the clip once it placed on your sequense and when opening up the motion editor you will be able to both promote and control / adjust the render settings

    OK, tried that and played with different settings including promote and the results are the same.  Just as with the original method :

    AMA link in 1080 50i project
    Follwed by Transcode to DNxHD120 in said project

    I get regular motion but we are back to the jaggy hoizontal lines not visible in the "import" method (that takes twice as long and produces wierd motion).

    The biggest downside (apart from not fixing it!) is the render time - up from 2:1 up to 10:1 depending on setting used!  Plus the hassel of laying each clip on the timeline.

    Thanks for the suggestion!
    Carl

    MC8.10 Win 7 64 with Dongle, Dual 10 core Xeon, Quadro K4000, Adaptec RAID 5-8x3TB, External TB2 4x3TB, 64G RAM, BM Intensity Pro 4K. NewBlue Titler 6... [view my complete system specs]

    Vote 1 - Dongles.

    UME an old engine, now with 4K, mags and furry dice....

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