Video noise: isolating cause

terrypin wrote on 5/18/2012, 3:33 AM

In several recent projects I've had video 'noise' in my MP4 exports. Here's a very short example:

Although most of the material was rather low quality (old photos like that in the example), I made the project at 1920x1080 because of a few higher resolution clips.

I found by experiment that the only way I good get an almost 'clean' result was to enable the 'HRD' option shown below.

(What is HRD anyway? Found nothing in Help or the manual.)

And rendering is much faster with HRD enabled, which seems counter-intuitive to me; I'd expect better quality to be related to longer rendering time.

I could also get a non-noisy result by using the 'MPEG4-simple' option instead of H264, But without close examination I assume that this will be lower quality overall.

With HRD unchecked, are there any obvious settings I've got wrong please?

--
Terry, East Grinstead, UK

Comments

terrypin wrote on 5/20/2012, 12:34 PM

None of the experts with any thoughts on any of this please?

--
Terry, East Grinstead, UK

johnebaker wrote on 5/20/2012, 5:01 PM

Hi Terry

More about the H.264 hypothetical reference decoder here

John

terrypin wrote on 5/21/2012, 2:49 AM

Hi Terry

More about the H.264 hypothetical reference decoder here

John

Hi John,

Thanks, but (gulp) way above my head!

But at least I now know what HRD stands for, even if I still haven't a clue as to when or how I should enable it!

Anything odd about my settings?

Here they are as links, instead of those blurry magix.info images, so you can actually read the details!

http://dl.dropbox.com/u/4019461/MEP-NoiseIssue-1.jpg

http://dl.dropbox.com/u/4019461/MEP-NoiseIssue-2.jpg

Are yours similar?

Does the visual appearance of the noise give you any clues? Ever see it in your own HD MP4s?

--
Terry, East Grinstead, UK

johnebaker wrote on 5/21/2012, 5:38 AM

Hi Terry

The only odd setting for me is the use of the DivX codec. For BD discs this relies on the BD player being able to play DivX encoded material.

I use H.264 with AVCHD mainly because my camera is also AVCHD and smart rendering saves a lot of time encoding.

The only noise I have ever seen was low light noise from my video camera when shooting on the wrong setting for low light and shooting in colour in very lowlight situatios - think night with half moon.

John

Scenestealer wrote on 5/22/2012, 2:39 AM

Hi Terry

So that I know what I am looking for - can you describe the nature of the noise.

From the Main Concept reference manual:-

The checkbox HRD conformance controls applying HRD conformance in the encoder. In
most cases it is recommended to disable this parameter whenever possible. However,some video formats may require HRD conformance, such as Blu-ray, Sony PSP, Apple iPod, etc. For general or custom presets, it is always disabled.

Can't tell you much about it though.

Peter

johnebaker wrote on 5/22/2012, 3:33 PM

Hi terry

Just re-read you original post - is the noise mainly in the old photos?

I presume you scanned them - what resolution were they scanned at?

Changing the resolution to high quality only works if the images are at least 1920 * 1080 or higher - I always take stills at least double this resolution ie 3840 * 2160.

If the old photos are scanned at for example 600*480 then you are magnifying the 'graininess' or noise in the image and this could be what you are seeing.

John

terrypin wrote on 5/28/2012, 3:24 AM

Hi Peter,

Did you view the YT example I gave in my first post? That's typical of the sort of noise I mean.

As mentioned, HRD did improve it, but I'd like to be able to render without that.

--
Terry, East Grinstead, UK

terrypin wrote on 5/28/2012, 3:37 AM

Hi John,

Yes, most of the noise seems to arise on zoomed JPGs.

I'm seeing it in old and new JPGs, both from scans and various digiicams. That YT example was a cropped 19 year old JPG, size 1170 x 1731. I expect poor quality when zooming/panning relatively small images, but this superimposed noise is a recent phenomenon.

--
Terry, East Grinstead, UK

johnebaker wrote on 5/28/2012, 4:05 AM

Hi Terry

The 'noise' are you referring to the apparent random black bars/grids/patches that appear on the Youtube video?

If so these look encoding errors where data is being lost.

Try using a different codec eg H.264 exporting the same video to see if it appears.

John

terrypin wrote on 5/28/2012, 8:22 AM

Hi John,

Yes, that sort of stuff. Just appears on a few clips as described.

As per my screenshots, I am using H264.

--
Terry, East Grinstead, UK

johnebaker wrote on 5/28/2012, 5:27 PM

Hi Terry

My mistake I forgot to say which codec to use in previous post.

You are using the H.264 container but using a DivX Plus codec according to your third image.

Try changing this to AVCHD or Blu-ray HD.

John

terrypin wrote on 5/30/2012, 2:16 AM

Hi Terry

My mistake I forgot to say which codec to use in previous post.

You are using the H.264 container but using a DivX Plus codec according to your third image.

Try changing this to AVCHD or Blu-ray HD.

John

Thanks John, but I've tried several options for that setting, including those two, and it makes no diffrerence.

I don't know how that previous example came to be set to DivX. The default is usually 'High', whatever that means. I'll step through my normal steps in a moment. But as a more practical tactic I've also uploaded my test project in self-contained form (8 MB) and you might want to unzip it and run it to see what happens.

http://dl.dropbox.com/u/4019461/TestNoiseExtract.zip

I've done scores of tests and although I still don't understand the underlying cause I have come to a few tentative conclusions:

1. Results are inconsistent. I can repeat several times with no changes to any settings and degree of 'noise' varies from virtually none to extensive.

2. It's worse if I remove my usual setting to Apply anti-interlace filter

3. Sometimes (not mostly) the noise also appears a set of vertical 'interference' lines in the preview monitor:

http://dl.dropbox.com/u/4019461/MEPNoise-Preview-1.jpg

Compare that with the original imported JPG:

http://dl.dropbox.com/u/4019461/23%20Hampton%20Way-6.jpg

4. The degree of noise seems related to other (non MEP) resources being used during rendering.

--------------------

My usual settings are shown in these screenshots:

http://dl.dropbox.com/u/4019461/MEP-UsualSettings-1.jpg

http://dl.dropbox.com/u/4019461/MEP-UsualSettings-1a.jpg

As a side-issue, I reckon that MEP has a minor bug here: it shouldn't display 'User Defined' when no settings have been changed since I selected my usual preset:

http://dl.dropbox.com/u/4019461/MEP-HD-UsualExportSetting.jpg

If that drop-down is immediately re-opened, the standard setting becomes 'User Defined'. So if you come back later to the project you could fruitlessly start looking for some setting change. It seems that merely opening the dialog is interpreted by MEP as 'The user has made a setting change'!

Anyway, continuing my normal steps, after opening Advanced video settings I see:

http://dl.dropbox.com/u/4019461/MEP-UsualSettings-2.jpg

As mentioned, changing 'High' to various other options (including AVCHD and Blu-ray HD)

http://dl.dropbox.com/u/4019461/MEPNoise-AVCpresets.jpg

made no difference. BTW. I haven't a clue what many of these options mean or when they should be used. Baseline? Main? etc. Nor do I understand most of the other setting areas in this Advanced vide dialog, such as under Profile. Level, Performance, etc. That's why I have always just left these alone!

Edit: I ran the same project in MEP17 and there was no video noise in the export. I tried several other exports which had noise in MEP MX - and they too were clean. So it looks like this is down to MX.

--
Terry, East Grinstead, UK

terrypin wrote on 6/1/2012, 4:41 AM

Here's a new project (8 MB) that comes complete with media, ready fror running:

http://dl.dropbox.com/u/4019461/NoiseTest-Extended.zip
It contains three separate JPGs, all zoomed using Movement > Zoom In.

When I run it in MEP17 and export to MP4 I get this clean result:

http://dl.dropbox.com/u/4019461/NoiseTest-Extended-MEP17.mp4

But when I run it in MEP MX I get this noisy video:

http://dl.dropbox.com/u/4019461/NoiseTest-Extended-MX.mp4

See my last post for details of settings; they're simply the standard 1080i PAL 16:9.

Give or take the degree of noise (from the MX export), those results are consistent. I'd be very interested to learn if any other MX user gets the same please?

--
Terry, East Grinstead, UK

johnebaker wrote on 6/1/2012, 2:13 PM

Hi Terry

I have tried the latest project you posted and exported 8 times using the settings you gave 4 using the DivX Plus codec and 4 using the AVCHD and I cannot reproduce any 'noise'.

I am puzzled as to what is causing this, even if another program is interupting MEP than it should just pick up from where it left off while the other program was being serviced by Windows.

John

johnebaker wrote on 6/1/2012, 4:15 PM

Hi Terry

Which update are you currently running?

Just downloaded the latest update 11.0.5.0 - looking at the bug fix list there was a problem fixed in 11.0.2.0 - where image artifacts after rendering certain projects with image scaling have been fixed (or possibly not entirely fixed).

John

terrypin wrote on 6/2/2012, 3:07 AM

John - you're a star!

I'd been labouring under the impression that I'd get automatic notofication of updates. But apparently not. I was on 11.0.1.4, several updates old. I just installed 11.0.5.0 (UDC2) and after two quick tests I'm delighted to see the noise has vanished.

Thanks a bunch, much appreciate your taking the time to help me fix this.

--
Terry, East Grinstead, UK

alexk wrote on 9/8/2012, 2:53 AM

This is also the answer to my problems. Almost hit a deadline and replicated a thousand DVDs with this output problem....

Anyway, I was searching for Digital Artifacts, Output errors, DVD export, etc.

So hopefully mentioning those keywords will lead other lost souls to this page.

Best wishes,

Alex