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View Full Version : AVCHD -> CineForm, color degradetion and aliasing



snicky
11-21-2009, 10:29 AM
I have finally bought my GH1 after reading about it on dvxuser for months! The camera is simply awesome, but the workflow is still a big pain for me. I shot some test footage in a park 2 days ago. 1080/24p. I decided to download trial version of Neoscene, converted all of the files with its codec and of course removed the pulldown. No doubt that true 24p looks terrific, but unfortunately in all of my shots I can observe some aliasing now, and, what's even worse, there is a huge color degradation. I dont know if Im doing something wrong or Im using bad settings. Have you ever seen something like this in your footage? Btw: should I use that deinterlace function in Neoscene or just remove pulldown only? Actually I tried both and without deinterlacing colors look better, but alasing seems to be worse...


Examples:

Aliasing

http://snicky.unipoker.pl/cf1.jpg



Colors


http://snicky.unipoker.pl/cf2.jpg



I forgot to say that I use Neoscene on PC.

Eugenia Loli-Queru
12-07-2009, 01:11 AM
If you're using vegas, make sure you removed pulldown used the "high" quality setting of Cineform, AND that you don't hit this problem: http://techblog.cineform.com/?p=1407

JackBayer
12-08-2009, 03:25 AM
Are those pictures zoomed in or original size?

snicky
12-08-2009, 07:15 PM
Thank you for your replies and sorry for multiposting.


Eugenia: I have tried all of the quality settings and these problems were still there. After the conversion I watched my footage with standard WMP and other players, so this definietely isnt a Vegas issue...


JackBayer: these are cuts from original 1920x1080, in all of my players it looks exactly the same



Camera settings used:
- STANDARD color space
- creative movie mode
- 1080/24p
- ISO 100, standard 1/50 - 1/60 shutter speed, low aperture
- stock lens with fader ND
- AFC
- iA off
- auto WB or "sunny", I dont remember sorry
- recorded on Sandisk Ultra II (class 4) 16GB

PerroneFord
12-08-2009, 07:37 PM
Why are you going through Cineform? Do you have a place to upload a few seconds of the AVCHD file? I'd like to see it BEFORE the run through Cineform, as this kind of aliasing is known to exist in the GH1 itself.

snicky
12-08-2009, 08:35 PM
Why are you going through Cineform? Do you have a place to upload a few seconds of the AVCHD file? I'd like to see it BEFORE the run through Cineform, as this kind of aliasing is known to exist in the GH1 itself.

I cant find this kind of aliasing in my AVCHD files, but colors of the sky are indeed not too smooth. Anyway, Cineform codec overblows this flow in a terrible way :( I wanted to use Neoscene, because everyone recommend it. Is there any other way to remove pulldown and transcode the footage so that it can work properly with Premiere or Vegas? I tried TMPGEnc, but Im not sure which codecs I should use neither for editing nor for a final render.

Im uploading the files right now and will post the links later.

PerroneFord
12-08-2009, 08:40 PM
Once you post the links, I'll see what I can come up with.

snicky
12-08-2009, 09:44 PM
Done.

http://snicky.unipoker.pl/00053.MTS
http://snicky.unipoker.pl/00076.MTS

PerroneFord
12-08-2009, 09:49 PM
What are the frame numbers for these grabs? I want to make sure I get exactly the same ones.

snicky
12-08-2009, 10:05 PM
Oops... I dont know, because I just took screenshots and paste them in Photoshop :/

PerroneFord
12-08-2009, 10:10 PM
Screenshots??????

Can you describe EXACTLY the steps you took?

snicky
12-08-2009, 10:46 PM
After transcoding, I opened the files in WMP on full screen and made some screenshots using Print Screen button. Then I pasted them in Photoshop and saved as top quality JPG. I understand that image saved in JPG loses some quality due to its own conversion, but in every player and in Vegas as well all these artifacts looked exactly the same = crappy.

I dont know if you understand me. The files I have uploaded are coming straight from the GH1. I transcoded these files in Cineform and then made these screenshots. You can try to encode the files in Cineform by your own and I think you will get exactly the same effect. Frame numbers are not especially necessary, because this footage coming out of Cineform looks bad in almost every frame.

snicky
12-08-2009, 10:53 PM
Anyway, I feel I did sth stupid, so Im uploading the transcoded .avi files as well :)

PerroneFord
12-08-2009, 11:15 PM
I understand the issue... believe me.

I just looked at your native GH1 files. I took them through as much of a lossless workflow as I could. You have a number of issues.

1. Your color saturation is exceeding the codec. You need to use the "superflat" setting or whatever it's called on the GH1. Dial your saturation back to about half what it is now.

2. You are recording interlaced. Which is absolutely destroying your resolution.

3. Taking a "screenshot" tells us nothing. Your monitor cannot get anywhere CLOSE to the resolution of your camera. The camera should be resolving about 800 lines per inch. You monitor is less than 100. So as soon as you take a screenshot, you've thrown 80% of the quality of the image away. This is NOT how you go about getting a still frame to examine. What you do in photoshop after that doesn't matter at all.

4. Converting to Cineform will only further degrade your images. Cineform is very good, but it IS slightly lossy. Don't do this unless you must.


There are workflows that will preserve more of your image, but honestly, your problems are starting in the camera, and then you've made a series of choices after that which have thrown away a lot of your quality.

PerroneFord
12-08-2009, 11:16 PM
Anyway, I feel I did sth stupid, so Im uploading the transcoded .avi files as well :)

No need.

8string
12-09-2009, 12:16 AM
Q: in your camera settings mode, you don't mention using a tripod. I assume you did? Or is the fuzziness because of the jump to a photo taken in Photoshop etc.? Are these a lot sharper on your monitor?

Chris Light
12-09-2009, 12:38 AM
Perrone, how would the deficincies(sp) in the OP's monitor have anything to do with his "screen shots"? i would think that the saved image is monitor-irrlevant.

everything else you stated as a possible issue is spot on. just looking for clarification on this. i own this cam. and i don't mean "i OWN this cam". i have it. :-)

PerroneFord
12-09-2009, 12:43 AM
Because he is not pulling a hi-res still frame from the video to examine these flaws. He's taking a low-res screen snapshot and showing us the aliasing. BIG difference.

Martti Ekstrand
12-09-2009, 01:23 AM
2. You are recording interlaced. Which is absolutely destroying your resolution.
2.1 If you are seeing interlaced from GH1 NTSC then you are not removing pulldown properly. It's a 24p recording in a 60i stream.

snicky
12-09-2009, 02:55 AM
You need to use the "superflat" setting or whatever it's called on the GH1.

I think it is called 'SMOOTH', but I can also prepare a custom one.



2. You are recording interlaced. Which is absolutely destroying your resolution.


In GH1 u can shoot 1280x720 / 60p or 1920x1080 / 24p coming in a 60i stream as Martti said. I still dont understand if that 24p in 60i is in fact interlaced and therefore has all the flaws of interlaced recording or not... Sorry, I am a photo guy, not a video guy :/



... as soon as you take a screenshot, you've thrown 80% of the quality of the image away. This is NOT how you go about getting a still frame to examine.

So how should I grab a still frame from my footage?



4. Converting to Cineform will only further degrade your images. Cineform is very good, but it IS slightly lossy. Don't do this unless you must.


I want to use Cineform, because I NEED to remove pulldown from 1080p footage. Furthermore files transcoded with their codec seem to work relatively fast in Vegas.



If there is another way to remove pulldown and encode footage to a loseless or almost loseless codec then I want to try it! But unfortunately I have only tried removing pulldown with TMPGEnc and compressing to Lagarith. It looks fine, but 1) compressing process is very slow, 2) files are terribly huge and both Vegas and Premiere cant read it :/ Maybe just because they are too big, however, I have i7 920, 6GB RAM, Geforce 9800 and a fast hard drive...

As I said, Im a photo guy, I dont understand all of that video technical issues. If anyone has a better workflow, please tell me.




Q: in your camera settings mode, you don't mention using a tripod. I assume you did? Or is the fuzziness because of the jump to a photo taken in Photoshop etc.? Are these a lot sharper on your monitor?


I didnt use a tripod. These artifacts look exactly the same on the video, so it's definitely not a Photoshop issue.

PerroneFord
12-09-2009, 05:47 AM
2.1 If you are seeing interlaced from GH1 NTSC then you are not removing pulldown properly. It's a 24p recording in a 60i stream.

Ah yes, I forgot about that. 24p wrapped in 60i. I was able to remove the pulldown to get to 24p. And the interlacing was gone. I forgot there was no other mode for 1080 on this camera.

PerroneFord
12-09-2009, 05:54 AM
I think it is called 'SMOOTH', but I can also prepare a custom one.


Ok, look into that. I think the folks in the GH1 area here have worked something up.




In GH1 u can shoot 1280x720 / 60p or 1920x1080 / 24p coming in a 60i stream as Martti said. I still dont understand if that 24p in 60i is in fact interlaced and therefore has all the flaws of interlaced recording or not... Sorry, I am a photo guy, not a video guy :/


Ah ok. Yes the 24p is not interlaced. This was my mistake. The footage is fine. It just takes an extra step to get there.



So how should I grab a still frame from my footage?


In Vegas, at the top of the preview window is an icon of a little floppy disk. Set your preview to best - full, and click that icon. It will let you save a .PNG or a .JPG. There is another way, but that way will suffice.




I want to use Cineform, because I NEED to remove pulldown from 1080p footage. Furthermore files transcoded with their codec seem to work relatively fast in Vegas.



There are plenty of ways to remove pulldown. BUT, to do it well, requires extra processing. That is one of the drawbacks of the GH1. And yes, the Cineform codec works fast in Vegas.



If there is another way to remove pulldown and encode footage to a loseless or almost loseless codec then I want to try it! But unfortunately I have only tried removing pulldown with TMPGEnc and compressing to Lagarith. It looks fine, but 1) compressing process is very slow, 2) files are terribly huge and both Vegas and Premiere cant read it :/ Maybe just because they are too big, however, I have i7 920, 6GB RAM, Geforce 9800 and a fast hard drive...


Recording to a lossless codec will ALWAYS make large files. That is their nature. And yes, it's slow. However, we can sort out the process of Vegas and Premiere not reading it. It's not because they are too big. I pull 4 hours worth or more of lossless footage into Vegas all the time.




As I said, Im a photo guy, I dont understand all of that video technical issues. If anyone has a better workflow, please tell me.


Ok, I'll get back to you. But "better" is relative. I can give you a higher quality workflow. But if you want small files that work fast in Vegas and are willing to accept the quality hit, then you are already using the "best" workflow.


I didnt use a tripod. These artifacts look exactly the same on the video, so it's definitely not a Photoshop issue.

tflak
12-09-2009, 10:11 AM
Ok, look into that. I think the folks in the GH1 area here have worked something up.

For the best all-around results, a lot of people have settled on Smooth with Contrast to -2, Sharpness at 0, Color at 0, and Noise Reduction at -2. These are good for greater control in post, and seem to coax the max from the GH1's AVCHD codec.

Others have the settings tweaked more towards getting the best in-camera results they can and set the Contrast to 0, and crank up Sharpness and Color to +1 or +2. Or maybe even push the Contrast up a bit.

In any case, the GH1 doesn't seem to need NR.

snicky
12-10-2009, 03:22 AM
OK, thanks guys for your answers. Next time I will go to shoot I will use these settings and then tell you if there is a difference or not.