DNxHD or Matrox or Vegas 10

JHendrix wrote on 12/7/2010, 6:51 AM

Any opinion as to weather to use Avid DNxHD or Matrox or just use Vegas 10?

Here is the AVCHD stuff I have (from Canon HFS11):

Streams
Video: 00:11:20.613, 29.970 fps interlaced, 1920x1080x12, AVC
Audio: 00:11:20.613, 48,000 Hz, Stereo, Dolby AC-3

--

I tested a Matrox conversion using Prism

I chose:

output: avi
encoder: Matrox I-Frame HD

Result:

Streams
Video: 00:02:46.166, 59.940 fps, 1920x1080x24, Matrox MPEG-2 I-frame HD
Audio: 00:02:46.303, 48,000 Hz, 16 Bit, Stereo, Uncompressed

I did one with Data Rate @ 140 and it looks pretty good + seems to play well in Vegas:

I do notice a slight added contrast to the converted footage. It looks less flat but not necessarily in a bad way.

I can not conclusively tell if playback is smoother but the "sometimes slow start" of raw AVCHD seems to be addressed.

--

I tested a Avid conversion using Vegas
I chose:

output: QT
encoder: DNxHD

Result:

Streams
Audio: 00:11:24.117, 48,000 Hz, 16 Bit, Stereo, 16-bit Little Endian
Video: 00:11:24.117, 29.970 fps progressive, 1920x1080x32, Avid DNxHD Codec

it looks identical to orig seems to play well in Vegas. It seem to play smoother than the Matrox.

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Comments

JHendrix wrote on 12/8/2010, 1:05 PM

and the bitrate is e.g. 115, 175, etc...?

PerroneFord wrote on 12/8/2010, 1:12 PM

Correct. You will find that your file sizes are moving proportionately with that number. Thus encoding at DNx60 will produce a file just over half the size of a DNx115.

There is a chart in that PDF that I linked you to that tells you how much disk space each of these choices use. You should use that as a reference. DNx36 is about 4 minutes per gig.

One other thing I've noticed is that the codec makes some adjustments for you. Like if I ask it to make a DNx36 file, it's expecting 1080/24p. If I feed it 1080/30p, it adjusts up to about 45mbps to provide quality similar to DNx36 at 24p.

Make sense?

JHendrix wrote on 12/8/2010, 2:24 PM

yes it does.

well I just did a 115 8-bit an honestly I cant tell the difference between that and the 175 10-bit. I guess the difference would show itself after adding effects and processing?

do you know of anyone that is using something in the realm of 115 8-bit for final master?

anyhow...I suppose I could just use a proxy and then swap back to the original source just before render.

PerroneFord wrote on 12/8/2010, 2:38 PM

Yes, I use 115 for mastering all the time. If I am going to DVD. I use DNx36 if I am going to the web.

Unless I am mastering for big screen, I don't usually use DNx175 or similar. I tend to stay around 100Mbps for most of my work, even with a lot of grading. I'll work in 10-bit if I've got a lot to do though.

So make a short clip of 10-20 seconds, and encode to DNx175 and DNx115, and DNx36. Grade them all heavily, and output to whatever you normally do. See what differences you can see... DNx36 definitely shows some issues, but the other two are darn close in my experience.

JHendrix wrote on 12/8/2010, 4:52 PM

i will make that test in the morning

can you tell me what you think "heavy grading " is?

for me, the most I usually put on a clip is color corrector (maybe) and secondary color corrector (which also acts as "levels" filter)

PerroneFord wrote on 12/8/2010, 5:02 PM

For me, heavy grading would be:

1. Basic color correct
2. Secondary color correct
3. Relight part of a scene
4. 2-3 gradients
5. Denoise
6. Slight softening or sharpening.

So generally 5-7 layers. I've done 5 layers on DNx115 destined for the web and been quite pleased with how it held up.

The stuff you just mentioned I do on native footage without worries.

JHendrix wrote on 12/10/2010, 4:11 AM

3. Relight part of a scene

how do you go about that?

PerroneFord wrote on 12/10/2010, 9:26 AM

I drop the exposure on a scene to a base level, then add lighting where I would have wanted it had I been on set. Takes a lot of time and effort, but it can be worth it.

JHendrix wrote on 12/10/2010, 5:59 PM

what do you "add lighting" with

PerroneFord wrote on 12/10/2010, 8:29 PM

In a color grading application, you have rather good control of the luminance and chromacity of every pixel in a frame. So I simply add more "brightness" where I want it, and add less where I don't want it. There are limits to this as you cannot replicate hard lighting and shadows if none was there when you shot. But changing the tonality of a shot is entirely possible and is done all the time.

In fact, I am working on grading an AOL episode right now and doing this very thing.