Thanks for posting this John. So Avid, what was wrong with making the
bit rate part of the name? Too easy, not cool enough... I never had to
look at a document to know the bit rate of DNxHD220. Maybe release 10,
oops I mean 2018.3 can have all the command names changed to 10 code. --J.B.
John Moore bigfish@pcbell.net [Avid-L2] wrote:
>
>
> According to this link Avid DNxHR HQX and DNxHR 444 are 12 bit. The
> rest are8 bit.
> DNxHR Codec Bandwidth Specifications
> <http://avid.force.com/pkb/articles/en_US/White_Paper/DNxHR-Codec-Bandwidth-Specifications>
>
>
>
>
>
> DNxHR Codec Bandwidth Specifications
>
>
>
> <http://avid.force.com/pkb/articles/en_US/White_Paper/DNxHR-Codec-Bandwidth-Specifications>
>
>
> I picked up on a 4K project in a bay with HD Rec709 monitoring. It had
> already been color corrected and I was just exporting. The delivery
> wanted high quality 12 bit. The source was Sony Raw from I believe an
> F55 or maybe an F5. The sources were linked. I kept the project in
> 709 YCbCr mode and set the project to 4096_2160 format setting the
> Output Hardware setting to 1920_1080. This all worked but I had to do
> a video mixdown to DNxHR HQX to be able to watch the sequence down
> without stuttering etc... This is nothing new I have found in my
> normal 4K projects I have to render a safe color upper effect to get
> reliable 10 bit playback.
>
> From this I exported to QT to DNxHR 444 and everything seemed to work
> fine. As I don't normally deal with super high end files I'm thinking
> I should have not used the video mixdown track when exporting because
> it had taken the Sony Raw ama linked clips and created DNxHR HQX media
> thereby lowering the source quality somewhat. In my mind the
> difference is small and probably imperceptible to the viewer but for
> the sake of the most pristine workflow I think I should have exported
> from below the video mixdown.
>
> Given they wanted 444 for delivery should I have switched the project
> to a 709 RGB project? I haven't played in the RGB project sandbox
> other than a couple of tests with the 1-254 ramp avid supplies in the
> supporting files. In my ramp tests I found the 1-254 ramp showed the
> proper over and under shoots in all projects except an RGB 709 project
> with the timeline quality set to green 8 bit. In the green 8 bit mode
> the over and under shoots in level were clipped at 0 and 700mV. It
> was strange that toggling to 8 bit quality had an effect on the
> overall level on my external waveform.
>
> Regardless of that anomaly in this particular case could I take the
> project that was colored in YCbCr 709 mode and just switch to RGB 709
> color space mode and have the levels track? I'm not back at the
> system I was on to check this out and in the heat of the battle I had
> no time to experiment. The core of my question is if the Sony Raw F55
> footage is ama linked would switching the project to RGB 709 access
> the source material as 444 and thereby give a more pristine file? By
> working in my normal project mode of YCbCr 709 am I downgrading the
> potential quality that could be derived from a Sony Raw ama link.
> Also where does bit depth play into all these factors. Given DNxHR HQX
> and DNxHR 444 are listed as 12 bit codecs what is Avid processing ama
> linked clips in. The timeline only offers 8 and 10 bit quality mode
> and given I have seen that effect the SDI output in the RGB 709
> project does it have any effect when exporting.
>
> I have no doubt that when I did the video mixdown to DNxHR HQX it must
> somehow reduce the accessible image quality but at that point I think
> I'm splitting hairs. I suppose there may be some variations when
> shooting Sony Raw that also might effect image quality potential but
> I'm not familiar with what options they have in the field. I would
> think Sony Raw is basically sensor data but is it?
>
> Bottom line should I have switched to and RGB 709 project and exported
> from the ama link track not the mixdown to maintain the maximum
> quality I could have?
> John Moore Barking Trout Productions Studio City, CA bigfish@pacbell.net
>
>
>
Posted by: john beck <jb30343@windstream.net>
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