(Video) Noise Thread - DVX100A - Request for help

D

dberton

Member
For the past year I have been trying to eliminate "noise" in the video signal from my DVX100A. There have been various posts about various amounts of noise in the video signal, with various suggestions on how to reduce or eliminate it in order to achieve the cleanest image possible. Specifically, the noise I am referring to is the 'digital snow' which appears in dark areas or mid-range colors (greys or other flat colors). Despite my best efforts, I have been unable to eliminate (or reduce to an acceptable level) the noise I get from my DVX.

First, a recap on my strategy to reduce noise. From tips from various respected members of this board over the past year or so, I have used the following guidelines when composing a shot:

- Lots of light. Wherever possible, more light is used to properly illuminate a shot.
- Correct white balance and black balance
- Master PED between -4 and -8
- Lowered Detail setting between -3 and -5
- Gamma curve "Black Press"
- Coring raised to reduce noise
- Chroma level down

Despite all of this, I still get noise. I am beginning to think there is something wrong with my camera. I know that the image looks 'good' overall, however I still see noise in certain areas of almost every shot.

Here is the result of a small experiment. The following is a 6 second shot of a car across the street from my house, which follows the guidelines listed above. f2.8, 24PA, zoomed all the way in, on an overcast day (so there is an even spread of daylight all around). I did not record this to tape -- I went straight to my laptop over firewire and capture the clip in final cut pro. Here is the original raw DV file, with no modifications or filters, which is 18MB. Please go easy on my server, and download this clip locally and do not stream it:

http://mosey.org/film/2007/noise/car.dv

Here is a smaller version (4MB) of the very same clip which has been encoded with h264 using a compression setting that faithfully reproduces the original DV file pretty closely (iow, the noise is retained):

http://mosey.org/film/2007/noise/car-14-x264-aac.mp4

When you look at this clip (especially at full screen), you will notice noise in the upper left of the frame, in the area of the green door. You will also notice noise along the bottom of the frame along the entire bottom of the grey car. With the above settings in place I should be able to turn on my camera and capture footage that is clean and crisp and ready for editing. Instead, I am constantly plagued by noise, which makes its way into my editor and spoils (IMO) a good deal of my footage.

OK. So here are my questions, and requests for help.

- Do you see the noise? Am I crazy and there is really nothing out of the ordinary? I have seen many other clips of DVX footage that look fantastic, and have no noise at all. Why do I get noise?

- Do my settings listed above ensure a noise-free image? If not, what should I try next?

- Could there be something physically wrong with my camera? If so, what do I do about it?

- Is someone willing to go outside their residence and film a neutral-colored car in their neighborhood in such a way as to contain absolutely no noise? I want to be reassured that it -can- be done, and which settings were used to achieve it. I have ftp space available -- please PM me and I will send you upload instructions for your 6-second raw DV clip.

I hope the root cause of the noise I get in the DVX100A will be found, so I can eliminate it altogether.

Thanks for helping.

db

Update: I've added a screenshot indicating the areas of noise, which are visible when the clip is playing:

http://mosey.org/film/2007/noise/car-14-x264-aac.png
 
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neither of your links worked for me. could it be that you have the gain on? check the gain setting inside camera menu mybe you have the lowest setting on the switch actually set to have gain. thats all i can say without seeing the clip.
 
Hi,

I don't have the same kind of shot for now, but i quickly compare with some shots of my own Pal DVX100B (one revision after your's) :
I have strickly the same kind of noise in the quiets part of the frame, like little dots dancing.
You (and me for sure) have look too much HVX footage !!!

Hope this help
 
matt s.: I've checked both links again, and they appear to be working fine. What specific error are you having? Perhaps there is a high server load at the moment; please try again, since I'm interested in your opinion.

As far as the gain issue, I have also double-checked that and I am not using any gain at all (it is on the "L" setting in the side of the camera). I am not aware of a setting which will change the value or effect of the "L" setting (only "M" and "H" can be adjusted via the menu); can you be more specific?
 
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matador43 said:
Hi,

I don't have the same kind of shot for now, but i quickly compare with some shots of my own Pal DVX100B (one revision after your's) :
I have strickly the same kind of noise in the quiets part of the frame, like little dots dancing.
You (and me for sure) have look too much HVX footage !!!

Hope this help
Click to expand...

Well, it only helps me in that I don't feel completely crazy. There is noise-- subtle sometimes, but always there, dancing about in the darker or mid-range colors of the frame. I was under the impression that the DVX100B had much less of a noise issue. The fact that it is there at all is a little disturbing.

The questions remain though: why is this happening, and how do you get rid of it (or at least reduce it to an acceptable level)?
 
It looks more to me like heat wave refraction. Also, did you have it fixed on a manual focus, because it also looks like it might be on auto and therefor it will keep readjusting. ?
 
jamesh said:
It looks more to me like heat wave refraction. Also, did you have it fixed on a manual focus, because it also looks like it might be on auto and therefor it will keep readjusting. ?
Click to expand...

Yes, I see a partial heatwave-type refraction happening in that clip. However, that is not what I am concerned about. The digital noise in the clip is separate from that slight refraction, and is independent of it.

Here is an image which indicates the three areas to watch carefully while the clip is playing (the noise is difficult to see unless the clip is playing):

http://mosey.org/film/2007/noise/car-14-x264-aac.png

Regarding the autofocus issue: the autofocus setting seems to have no impact on the presence of noise. The noise exists whether or not the shot is in focus or not, or whether autofocus is enabled or not. If the shot is out of focus, there will simply be noise on top of the unfocused footage.

db
 
well dberton you are not crazy at at alli do see noise two .thi is what you can do you need a plug in that can take the noise out completly the name of the plog in is Dynamic Noise Reduction 1.0.1 is goin to help u aloat and the good thing about this is that is free you can down load it here http://www.mikecrash.com/modules.php?name=Downloads&d_op=viewdownload&cid=13 i down load your clip and i use the plug in it and toock all the noise away if u interested on seen the result who it came out you can down load it here http://rapidshare.com/files/26806432/car.avi.html i hoap thi may help u
 
flex said:
well dberton you are not crazy at at alli do see noise two .thi is what you can do you need a plug in that can take the noise out completly the name of the plog in is Dynamic Noise Reduction 1.0.1
Click to expand...

Thank you for pointing this out. This plugin does appear to reduce the noise problem a good deal. However, there are two issues with it.

The first is, it is only for Vegas (I am a final cut pro user). The second is, it only addresses the symptom, not the disease. There is still noise in the source DV file which should not be there. Removing it after the fact is useful and perhaps necessary in certain cases. However, IMO, the default footage captured by the DVX100A should not contain such a noticable amount of noise. I would like to find a solution that addresses the root cause of the problem, whatever that may be.
 
What i try to say to you with my HVX joke is that, for me, the amount of noise you see is normal for the DVX. It is maybe increased by the fact that your looking for noise and on a mac monitor. On a TV, the noise will certainly be less.
And add the fact that with all his quality, the DVX rely on DV compression, who certainly add noise…
 
when i click the links i just get sent to a page with a lot of code. this is using safari and mac.
as far as the dvx100a its not a noisless camera. maybe you are just looking for the noise too much. i dunno but i never see the noise as a problem and as most would agree it resembles film grain more than noise. cine like d will make image noiser as will cine matrix. using norm matrix tends to lessen the noise issue as does proper exposure.
 
matt s. said:
when i click the links i just get sent to a page with a lot of code. this is using safari and mac.
as far as the dvx100a its not a noisless camera. maybe you are just looking for the noise too much. i dunno but i never see the noise as a problem and as most would agree it resembles film grain more than noise. cine like d will make image noiser as will cine matrix. using norm matrix tends to lessen the noise issue as does proper exposure.
Click to expand...

I agree with you on exposure, and also using 'norm' matrix, etc. I stay away from cine-like-d.

I also understand that -some- level of noise is to be expected. What I am wondering is: how much should I be expecting? From my sample clip, I'm worried that the expected amount of noise is too much, especially examining it at full screen.

Using safari, simply right-click and select "Download Linked File". If it renames it, simply rename it back to the proper extension before opening in quicktime. After you get to look at the clip, please come back to tell me your opinion of the noise (too much?, expected?, something wrong with my camera or settings? etc.). Thanks.

db
 
dberton said:
I agree with you on exposure, and also using 'norm' matrix, etc. I stay away from cine-like-d.

I also understand that -some- level of noise is to be expected. What I am wondering is: how much should I be expecting? From my sample clip, I'm worried that the expected amount of noise is too much, especially examining it at full screen.

db
Click to expand...


If you look your footage "full screen", that is more or less 200% on an average computer monitor, the noise will be more obvious, as blur, aberation etc etc…

Do you still see the noise on a CRT TV ?
 
Thanks to everyone who has replied. I am very close to just accepting the footage produced by the DVX100A , even though it contains a little noise in certain areas even with tons of light as well as the appropriate settings on the camera to reduce the appearance of noise.

I am still very interested in getting someone's help with my last request. I would appreciate it if someone could head outside during a day with plenty of light, and create a short 5-second shot which is composed in such a way as to be as clean and noise-free as possible. I have ftp space available to upload the raw DV clip (it should be 15MB or so, you can PM me for the ftp details), or you can use rapidshare.com or something similar. I would like to compare the raw DV output from someone else's DVX100A with mine.

Thanks again.

db
 
Bump.

I'm still hoping someone can help me out here. I'm just looking for a short clip (5 seconds would be fine) so I can compare the raw DV output from your camera to mine in order to evaluate the noise problem better. (See the post directly above.) If no one can help me out, I'll let this thread die, although it is very hard to believe that the DVX100A has such a noticeable problem with noise, and that no one can step up to champion this camera.

In related news, I finally received some raw DV footage from a different camera: the Panasonic PV-GS400. There is good news and bad news.

The good news is: there is a very similar noise pattern in the footage from this camera. Not exactly the same, but it is there. A subtle "dancing pixel" behavior, especially in the darker and mid-tone areas, and especially when viewing at full screen. Therefore, I think I am leaning more toward the idea that the cause of this sort of "noise" is simply the result of DV compression (which is 5 to 1).

The bad news: in comparison to the DVX100A, the footage from the PV-GS400 is -much- cleaner and more noise free. Both cameras appear to create some noise (again, this can be accounted for by the DV-compression theory). However, the PV-GS400 is head and shoulders above the DVX100A in terms of the signal-to-noise ratio. This dumbfounds me, and I cannot explain it.

Someone please step up. Show me that the DVX can produce clear, noise-free images right from the camera as, I believe, it is designed to do.

Thanks.

db
 
Rubix³ said:
I can help you once I'm home on lunch, which will be in about 3 hours. I will PM you.
Click to expand...

Fantastic, thanks a lot. The top of this thread lists some settings I used to obtain the cleanest possible image from the DVX. You may have some better ideas or ways to improve the image further.

And I am also interested in the final settings you wind up using.

db
 
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dberton said:
I'm still hoping someone can help me out here. I'm just looking for a short clip (5 seconds would be fine) so I can compare the raw DV output from your camera to mine in order to evaluate the noise problem better. (See the post directly above.) If no one can help me out, I'll let this thread die, although it is very hard to believe that the DVX100A has such a noticeable problem with noise, and that no one can step up to champion this camera.
Click to expand...

The DVX line is fairly noisy, and the A model is the worst of the bunch. The noise tends to be somewhat monochromatic, so that it resembles film grain moreso than traditional video noise, and many think it has a somewhat pleasing appearance.

You will always perceive more noise when editing up-close on a computer monitor/LCD, and looking at the footage and still frames for extended periods of time. However, on playback on a normal TV, most people will not notice it at all, even if you still do.

Therefore, I think I am leaning more toward the idea that the cause of this sort of "noise" is simply the result of DV compression (which is 5 to 1).
Click to expand...

DV compression will create compression artifacts (blockiness, quantization/mosquito noise around edges), but not video noise. If anything, DV compression will reduce noise as it simplifies the image.

The bad news: in comparison to the DVX100A, the footage from the PV-GS400 is -much- cleaner and more noise free. Both cameras appear to create some noise (again, this can be accounted for by the DV-compression theory). However, the PV-GS400 is head and shoulders above the DVX100A in terms of the signal-to-noise ratio. This dumbfounds me, and I cannot explain it.
Click to expand...

The GS400 has a CCD over a megapixel, which must be downscaled to DV resolution (1/3 MP). The downscaling averages out much of the noise. With no gain, the GS400 is very clean as a result. Even up to 6dB gain, it looks very clean.

The DVX on the other hand has basically just enough pixels to create a DV image 1:1, so any noise at a pixel level, you will see.

Show me that the DVX can produce clear, noise-free images right from the camera as, I believe, it is designed to do.
Click to expand...

I wouldn't agree it's designed to do that. It is designed to produce film-like images, in which a little grain is acceptable. The original or B model would get you a cleaner image, but those are even grainier compared to some other cameras.

Unless your camera has a physical fault, which is unlikely, you probably just need to adjust your expectations for the camera. The images can be beautiful, noise or not.
 
Thanks to Joshua for a good explanation of the state of affairs. I can now accept the slight 'noise' or 'grain' produced by the DVX, which happens to be especially noticeable in the A model. Proper exposure is essential, as well as using adequate lighting.

Also thanks to user Rubix³ who sent me some raw DV footage for comparison. The same sort of general noise pattern is evident in his source footage as well. But I believe output to compressed h264 or to DVD will effectively eliminate the noise, or it can be eliminated/reduced while editing.

For those looking for the clearest and cleanest possible image, the settings at the top of this thread can be a good guideline. To get any more clarity (and resoution), you will need to step up to the HVX or something similar.

db
 
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