Very poor rendering quality for HD files in VS X4

[Peter100]

I am getting very poor rendering quality for HD files. If the clip is “untouched” by VS it will render fine. However any changes to the clip either by adding transition, modifying brightness, color, adding title overlay etc. causes significant lost of quality and creates very flickery output with jerky movements. Here are examples of what I am referring to:

Original clip
http://www.4shared.com/video/eH9DSrPj/Original.html

Same clip but rendered by VS X4
http://www.4shared.com/video/QD0j0sKB/Rendered.html

Could someone please try to replicate the problem on your system using provided source clip and project file and report back the results to the forum.
I just want to confirm that it is not PC and program instalation related, but it is VS X4 itself that is cousing it.

Here are the steps to do the test:

1. Download files from provided links:
a) Original clip : http://www.4shared.com/video/eH9DSrPj/Original.html
b) Project file : http://www.4shared.com/file/vlv3wMpu/Test.html
c) Project screen shot: http://www.4shared.com/photo/D-zkxxuK/Test.html

2. Create folder in your C dirve called “Test” and place downloaded files in it.

3. Open provided project file in VS X4. This should have the original clip placed on the time line twice.
The first one is not modified clip and the second one has modified brightness just to force the rendering)

4. Render it to the file using MPG Optimizer. (i.e. Share -> File -> MPG Optimizer -> Accept -> Save)
This should produce AVCHD 1920 x1080 60i file. See the project screen shot “Test.jpg” as a reference.

5. Play both source and rendered files in Windows Media player or TV and compare the smoothness of movements.
Report back to the forum your findings.

Regards,
Peter

[Ken Berry]

Well, I can certainly replicate the problem. And it seems to be the same whether using Optimizer (which I never normally use), or Same As First Clip. I also tried it with Share > Create Video File > Custom, chosing MPEG transport stream as the format and then customising to the same properties as the original. I also tried the latter but adding another filter (AutoLevel). But in all of them, while the car appeared smooth, the background rocks in the second clip appeared slightly flickery, whereas they too were smooth in the first clip.

I am unable to account for it. But I am interested when you said that the second clip had its brightness modified. How did you do that as X4 does not show any filter having been applied in your VSP.

[Peter100]

Thank you Ken for doing this test. This confirms that the problem is not PC/setup related but it seems to be related to algorithm that VS X4 is using for rendering HD content. For whatever reason the rendered by VS portion of a movie have always significantly lower details, much courser color gradient (see sky portion of a provided clip) and flickering appearance. This issue is very consistent, it happens with all of my HD clips ( i.e. is not specific clip dependent) and it shows in all of my projects.

In provided example I have applied brightness filter set to +2 for clip # 2. (you can see the filter mark on 2nd clip in the provided Test.jpg screen capture). This was done just to force the rendering to happen while keeping clip appearance close to original. Not sure why this does not show when you open the project, but what is important that VS rendered it as intended.

As mentioned this problem is triggered by applying any filter, any transition, title overlay, or any change for that matter that will require rendering. It is really pity that this is happening as it degrades the produced movie quality in sections where modifications are applied. As you may know from your own experience in any movie there are quite a few of them required.

Since it has been verified that it is not my specific PC set up related, is it possible for you as a site administrator to bring this issue to Corel attention for possible correction?

Regards,
Peter

[Ken Berry]

Yes, I will draw it to their attention, though that does not guarantee any rapid action on their part.

I have to add that I normally do my HD work using HDV rather than AVCHD, and I also use a lot of filters and effects with that. Yet I have never had that flickering effect. I have also produced AVCHD from my HDV (both as experiments but also for burning to AVCHD discs) and also don't get your effect.

I guess I should try some other original source AVCHD and see if I can replicate the problem with that...

[Ken Berry]

For the record, I have now drawn the matter to the attention of the senior Corel exec in charge of development of Video Studio, and given him a link to this thread.

[erdna]

I downloaded the original file, rendered it with some text, and indeed the rendered file shows strong artifacts in the moving rock parts. This recalls me to the time that the "mpeg family" was born (almost 30 years ago). Special video files were available then with structured parts moving in different directions and at different speeds (which we called killer files) to show that the long GOP codecs were worthless... Applying filters, text,...forces decompression and recompression. Rough motion vector quantisation and too large motion area division blocks caused the problem. Times changed, and powerfull codecs solved these problems (H264 with CABAC) but I think that Corel prefers cheap and "fast" coding which inevitably causes these artifacts. I think however that many consumer NLE's would do the same with this file...

[Ken Berry]

Thanks for also trying it out, André...

Interestingly enough, I got a quick response from the Corel exec mentioned above. He suggested I/we try it with hardware acceleration disabled. I did so, but did not see any significant difference in the flickering. It may have been a little less flickery, but only by a very small margin...

[Peter100]

Hi Ken,

I have tried rendering with and without hardware acceleration and similarly as you do not see any significant difference.
Please let me know if you or Corel need more samples where this issue is even more visible/pronounced.

Regards,
Peter

[aljimenez]

I never use the codecs that Corel comes with. Have you tried rendering your file with another codec? like for example the fddshow one, which is my favorite... Al

[Peter100]

Al,

Could you please describe how this can be done in Corel VS X4 ?

Peter

[aljimenez]

Could you please describe how this can be done in Corel VS X4 ?
Peter

Go here: http://ffdshow-tryout.sourceforge.net/
Installation is straight forward. Then ffdshow will show up as one of the avi available codecs. It has lots of customization and it produces as high a quality as you want... Al

[Natal]

Al, the only encoder driver that shows up in VS is the Ulead MPEG.Now encoder. We don't know what you are talking about because there doesn't appear to be anyway of using anything else.

[lata]

Hi

did you guys disable Smart Render, then try to create the video file?

this seems to improve things for me?
i used VLC player to view the files, the first attempt stuttered when playing the last half of the file.

With Smart Render disabled the whole clip seems to play ok

Don’t know if this is significant but the bad video is 23.724 KB
The two good clips I made, Optimiser and Same as First Video… are both 23,316 KB

[aljimenez]

Al, the only encoder driver that shows up in VS is the Ulead MPEG.Now encoder. We don't know what you are talking about because there doesn't appear to be anyway of using anything else.

After you install ffdshow, it will be listed as an option when you create any template with avi type. In fact to get more codecs you need to install them on Windows 7. Lists of codecs thaat can be installed are often posted by Corel in this forum... Al

[Natal]

Ya, but he is talking about AVCHD 1920 x1080 60i files.