DNxHR HQ vs SQ

[Offbeat Bryce Productions]

Hello,

My camera records as AVCHD .MTS files at 28Mbps.

I'm currently working on a documentary project where eventually I will have (estimate guess) over 1TB of footage. Since I won't end up using all the footage in my final edit I want to only Transcode from in to out using Prelude what footage I actually need. Is it a waste of disk space to transcode to DNxHR HQ or SQ 10 bit since my camera only films in 8 bit? If so then is transcoding to HQ or SQ better in 8 bit? If so do I pick HQ or SQ for DNxHR? I obviously want to retain the quality but not sure wheter HQ or SQ is best.

I did a test where I transcoded time selected clips in SQ and that was about the same size as AVCHD and the quality looked okay but I'm just not sure if that's going to be fine when I start the color correction and the final export.

[R Neil Haugen]

Here's a table of the compression rates of the DNx codecs ... unfortunately, this doesn't give an Mbps rating though, as that would of course differ depending on frame-size/rate I'm thinking. From what I can tell, the compression ratio is similar for both DNxHD and DNxHR.

Neil

[Offbeat Bryce Productions]

Would you say that HQ 8 bit is better for me or SQ 8 bit? I could be wrong but isn't 10 bit overkill when my camera only records in 8 bit?

[R Neil Haugen]

10-bit might be overkill,but as you're only transcoding pieces, I'd go with the HQ over the Sq ... the DNx codecs are great, but you'll get less artifacting/macroblocking due to compression with the higher bit-rate/lower compression.

There's a certain level of just it needs enough data to work best with video. And for projects with miles of footage, well ... it just takes disc space.

Neil

[Offbeat Bryce Productions]

I was able to us HQ 8 bit and save 300GB so far.

[Offbeat Bryce Productions]

What exactly is 444? I read it's best for intensive effects. But would it really make sense to use that ever with my camera? SQ is the smallest size for me so far compared to my entire SDXC card.

[Offbeat Bryce Productions]

also, is it going to be bad to color correct native AVCHD .MTS? I ask because I'm wondering if it makes more sense to transcode after I have edited everything and then I can color correct. Just not sure what the best scenerio is. because DNxHR HQ is larger files than my native media. Couldn't I just edit and color correct in .mts files and use proxy playback if I needed to if something was slow?

[R Neil Haugen]

The "4" bits are how much color data is carried in the codec. It's based a bit on the debayering schema ... and how much color data is retained directly in the file, and how much is dumped and 'recreated' from the Luma data in de-encoding for playback/editing.

This page explains it pretty well ...

The Video Road – Color Subsampling, or What is 4:4:4 or 4:2:2??

Download MediaInfo, and when you've got the icon on your desktop, drag/drop one of your original files onto it, then in that app, select viewing in "Tree" mode.

It will give you the data that you need to know to pick a DI codec/settings for your transcodes. What's the bitrate in Mbps, what is the bit-depth (which for yours will be 8-bit apparently), and what is the color-depth ... likely 4:2:2, but good to actually check.

Media Info:        https://mediaarea.net/en/MediaInfo

Choose video encoding settings (between a preset and your alteration of the settings to taste saved as a custom preset) that give you at least a bit higher bit-rate (less compression is better!) than the originals, and maintains color depth. Saving 4:2:2 as 4:4:4 is a waste, of course. Doesn't help.

Neil