-
Proper use of DNxHD Codecs
Hey guys. I have always used AVCHD straight out of the camera (both DSLRs and dedicated video cams) since PPCC can edit AVCHD natively, but even with my gaming PC, it still can be taxing after a while. I have stayed up night after night researching which codec to transcode my footage to using Prelude to help me not only get better performance, but also to help me be able to push my grading capabilities a little further, since I tend to grade a lot. Needless to say the amount of good and bad info out there to sort through is becoming overwhelming! I have narrowed it down to DNxHD since ProRes is primarily designed for use on Mac and seems to have a lot of extra workaround to be had before you can use it on Windows (unless of course I am wrong about that). I found on the Avid website that DNxHD 175x is equivalent for the most part to ProRes HQ. I also read where x means 10-bit, which is what I wanted. So, for my first question, is 175x the best option out of the massive list of options you get with DNxHD? To clarify, a lot of my work is used for online promos for companies, but I will also be producing two nationally televised shows for the Pursuit Channel starting in August, so if there is a “best” option for each situation, I would love to hear it. Also, in Prelude, to transcode to DNxHD, the option for Format is DNxHD MXF OP1a. Is there a difference between that and just DNxHD? I really would like to find the best option for both the website material and for the televised material. Also would RGB 444 be a better option since I grade a lot? I think you can only use RGB with either DNX 350X or DNX 440X.
Second, in order to help my PC while editing in PP, I read where you should set what you are rendering to in order to help with the reading of the files, or something like that (like I said, my head is hurting now haha). So what I was going to do was start a new sequence and under Sequence Presets, select the same preset that I was transcoding my files to. Is this correct? Anything else I should do to help with the render and preview files with this codec?
My next question is back to the DNxHD codec options. Most of what I shot for the project I am currently working on (online commercial) is in 24fps, or 23.976 as far as editing goes, but some of the shots I did in 60fps, 59.94, in order to use slow motion. Prelude doesn’t give you the option for 59.94 or 60fps with the 175x codec. Do I still select 175x 23.976 for the transcode for those files and just bring it into PP just like I do the other files and then actually change the frame rate inside PP using “Interpret Footage – Assume this frame rate” in order to make it work correctly? Otherwise I am not sure how to bring a 60fps video into my 23.976 timeline without screwing it up. For the record, I have always used interpret footage in the past and changed it from 59.94 to 23.976 in order to achieve slow motion and keep all frame rates in line. I just am afraid to put something in a 23.976 timeline that wasn’t actually recorded at 24fps. I have done this in the past, but I didn’t know if this was wrong to do and if it was messing things up.
My second to last question (I promise!) is about the nationally televised shows. I will find out when I get there next month what the frame rates for the shows are, but I am assuming that they will likely be 30fps, or 29.97. Just like with 60fps, DNxHD 175x does not have a codec for 29.97. If that’s the case, then should I not use 175x and instead use something else, like 220x? Also, is there any real difference between 23.976 and 24, 29.97 and 30 and 59.94 and 60fps? I don’t quite understand the difference between whole frame rates like 24 and partial frame rates like 23.976. My cameras say they are shooting at 24p, but I’ve always gone with 23.976 when editing because I read to do so. Not sure if this is correct and even why this is. I would definitely love to know!
My last question is about exporting. Normally I would export to the web, or to BluRay when actually burning disks, using the exact same method for both. This was to go to export and select H.264 for Format and HD 1080p 23.976 for Preset, then select VBR 2 Pass, Maximum Render Quality and so on. Do I now export the final product to DNxHD MXF OP1a – 175x 23.976, or whatever codec we decide to use, to keep everything the same as within the timeline? Or do I export to something else?
Sorry for all the questions! I have researched this to death and have found a lot of answers to a lot of questions, but not to these exact questions. Codecs are pretty confusing to me, but I know that they will be helpful in the end. I just want to find the best options for my website content and my televised content so that I know what to use to give me a more proper workflow. I have learned a lot editing over the years, all self taught, and have managed to do decent work, but I want to become better and more efficient, particularly in my workflow. Thanks a lot guys!
-
3 Replies
-
DNxHD can be formatted with Quicktime ie MOV or MXF ie OP1A as an example. The MXF DNxHD performs better on windows and is native to Adobe CC. That is what I would suggest using. Keep in mind though you can also download Cineform and convert the AVC media to that. Cineform is a better codec than DNxHD but requires you to install their software to have the option available in Media Encoder.
Matching Sequence settings can be done just by dropping in 1 of the media files to create the sequence. However the frame aspects are really the only part that matters when you select sequence settings. The Adobe player will still decode the media regardless of what you set the sequence settings to.
Eric-ADK
Tech Manager
support@adkvideoediting.com -
Can’t help with the Avid questions, however most camera and software vendors “round” the numbers for simplicity, so 29.97 becomes 30, 23.976 becomes 24p and so on.
I believe the first Canon DSLR that offered video recording did record an actual 24fps, with later models updated to record a correct 23.976 for video.
In the bin in Premiere, right-click a clip to see the specs. Drag and drop a clip onto the “New Item” icon at lower right of bin, next to trash can. This will create a sequence with proper settings for your media.
For Blu-ray, rather than exporting to “H.264”, choose “H.264 for Blu-ray” and select the correct preset to match your footage. This will produce Blu-ray-ready video that will not need to transcode in Encore. If you simply used an H.264 preset before, Encore will in fact transcode that (re-encode) since it is not “Blu-ray legal”.
Thanks
Jeff Pulera
Safe Harbor Computers -
The numbers of DNxHD refer to the bit rate of the file. So more frames in the picture equates to a higher data rate. These are some of the possibilities:
23.98 the possible DNxHD codecs are: 36, 115, 175, 175X.
25 the possible DNxHD codecs are: 120, 185, 185X.
29.97 the possible DNxHD codecs are: 145, 220, 220X.
(This Wikipedia link is really a good reference: https://en.wikipedia.org/wiki/List_of_DNxHD_codec_resolutions)If your source material was only 8 bit you really aren’t gaining much by making it be 10 bit later on. As a best practice I always try to match the bit rate of my source material to the a DNxHD or ProRes bit rate.
Reply to this Discussion! Login or Sign Up