Getting the Best Picture Quality from Video Studio 10+

jchunter · Post by **jchunter** » Fri Aug 18, 2006 12:45 am

I ran across an old study (re-posted below) that I had written two years ago, using Video Studio 8.0,and posted on the old forum. Today, I ran some additional tests, using Video Studio 10+ with an IS0 12233 resolution chart, Motion1 test clip (uncompressed AVI), and standard definition Mpeg2 video clips that had been captured as LFF (Lower Field First).

These tests reaffirmed that if the Mpeg2 video is converted to SQUARE pixels and the bitrate is 8Mbps, it can be recursively edited and re-smart-rendered with no discernible degradation (I repeated this sequence 5 times with two different field orders: LFF and FB). I restored proper 4:3 aspect ratio by converting the final video file back to NON-SQUARE pixels after all the re-editing. Original image resolution was preserved, as measured on the ISO resolution chart.

A new finding was that wide screen video (16x9) can be repeatedly re-smart-rendered without visible degradation even if the video is encoded with NON-SQUARE pixels. Go figure.

Unfortunately, I also found that Ulead has not yet fixed the bug (disclosed in the original report) that degrades re-rendered Mpeg2 image resolution, when it is encoded with NON-SQUARE pixels, in 4:3 aspect ratio.

Conclusion: These findings demonstrate that:
1) Mpeg2 video is very editable and capable of producing excellent quality video even when re-edited/re-rendered many more times than should ever be necessary in creating home video.
2) It is time to place the blame for bad Mpeg2 editing on the real cause – Video Studio’s buggy software rendering of NON_SQUARE pixels.

REPOSTED REPORT (all tests apply to mpeg2 with 4:3 aspect ratio)

Getting the Sharpest Images

Recently there have been a number of queries in this forum about how to get the sharpest images and video. So I made a test project using stock Image Resolution Patterns with some of my video clips and created about a dozen different video files with different combinations of property values and burned them on a DVD. Differences in picture resolution that were subtle on a picture of landscape were glaringly obvious on test patterns. The results surprised me and may surprise you.

Summarizing the results:

The best resolution was obtained by (1) UNchecking the “Perform Non-Square Pixel Rendering” property, (2) Inserting images into the project timeline with their maximum resolution while Resampling Preferences were set to “Best” and “Keep Aspect Ratio,” and (3) Matching the Project and Burn properties to those of captured video clips.

Images that were scaled to the (recommended) 4:3 aspect ratio displayed as slightly squished horizontally when rendered with square pixels. Squishing was evident when DVD was played on computer or DVD player/TV as well as when the video files were played through Windows Media Player. The squishing does NOT show up on the Video Studio instant playback or the Share/Playback.

Video/Audio sound sync was unaffected by mismatching the Frame Type properties. PNG files did not show better resolution than high quality jpegs but required about twice as many bytes of storage.

Image Resampling Preferences were tricky because they take effect only when inserting an image into the timeline (i.e., changing the preference later has no effect on images already in place). Moreover, selecting the “Fit to Project Size” Resampling preference significantly degrades the resolution of those images that are inserted when the preference is set.

Test setup:
I found several resolution test images at www.bealecorner.com. Navigate through the TRV900 page or go direct to http://www.bealecorner.com/trv900/respat/eia1956.jpg and http://www.bealecorner.com/trv900/respat/reswedge.png. These can be downloaded in both png and jpeg formats and in several different pixel resolutions.

These were cropped and/or resized to simulate a user who might try to pre-scale his images prior to introducing into a Video Studio project. I made several different projects with different combinations of these images and mixed in some of my own video clips and images. I then created several video files with combinations of Properties such as Frame Type: (Upper/Lower Field First and Frame Based) and Square/Non-Square Pixels. I burned about a dozen onto a DVD and viewed the results played in interlaced mode through a Phillips 724 DVD player with a component video connection to a Pioneer projection HDTV.

TDK1044 · Post by **TDK1044** » Fri Aug 18, 2006 12:50 pm

These tests reaffirmed that if the Mpeg2 video is converted to SQUARE pixels and the bitrate is 8Mbps, it can be recursively edited and re-smart-rendered with no discernible degradation (I repeated this sequence 5 times with two different field orders: LFF and FB). I restored proper 4:3 aspect ratio by converting the final video file back to NON-SQUARE pixels after all the re-editing. Original image resolution was preserved, as measured on the ISO resolution chart.

Interesting results, John. How much degredation is there with re-rendered Mpeg2 when it is encoded with non square pixels in 4:3 aspect ratio? Typically, my MPEG2 footage burns as 3rd generation footage, in that my captured footage is generation 1, I then render sections of my project creating generation 2, and finally I make a completed video file of the whole project creating generation 3. I realize that I could skip step 2 and just render the whole project without having rendered the sections, but I've always been happy with the end result. I'm just interested to know the difference between generation 2 and generation 3 MPEG2 footage when all has been rendered using the NON SQUARE pixel setting?.

jchunter · Post by **jchunter** » Fri Aug 18, 2006 3:05 pm

Terry,
Video of actual scenes (landscapes, people, etc.) don't show it but there is noticeable softening of edges on a resolution chart after two successive re-edits (3rd generation, in your terms) of NON_SQUARE PIXEL 4:3 mpeg2. I will prep some framegrabs and post them ASAP.

BTW, my workflow is, usually, a single edit step on the captured video and out to the project video file, which has been widescreen (16x9) aspect ratio, ever since I dumped my analog camcorder.

TDK1044 · Post by **TDK1044** » Fri Aug 18, 2006 4:36 pm

Going forward, I'll un-check the 'Use Non Square Pixel Rendering' box until my final Render of the completed project.

dr.onestone · Post by **dr.onestone** » Fri Aug 18, 2006 6:19 pm

Can somebody please explain me what the feature "'Use Non Square Pixel Rendering'" really means?
Thanks in advance

jchunter · Post by **jchunter** » Fri Aug 18, 2006 6:31 pm

For an explaination of Non-square pixels, see http://www.3ivx.com/support/par.html
There is a better explaination covering PAL video here http://www.mir.com/DMG/aspect.html

Here are some res chart frame grabs:

1) Square pixels, 4:3 aspect ratio unedited:

2) Square pixels, 4:3 aspect ratio after 5th edit:

3) Non-Square pixels, 4:3 aspect ratio unedited:

4) Non-Square pixels, 4:3 aspect ratio after 2nd edit:

Notice that the vertical resolution has decreased from 5 to 4, horizontal resolution has not decreased much numerically but the vertical edges have softened.

TDK1044 · Post by **TDK1044** » Fri Aug 18, 2006 6:36 pm

If the finished project is to be played back on a television monitor, then non square pixels will produce a better visual playback. For playback on a computer, this option can be unchecked.

TDK1044 · Post by **TDK1044** » Fri Aug 18, 2006 6:39 pm

Pretty conclusive, John. Very helpful. Thanks.

blplhp · Post by **blplhp** » Fri Aug 18, 2006 9:31 pm

jchunter,

I capture video from my DV camcorder in NTSC format, type 1 DV_AVI, lower field first, 4:3, 720 x 480, 29.97 fps. I edit in this format in VS10+ Video Editor. When I create my video file, it converts to MPEG-2, DVD-NTSC, 4:3, 720 x 480, 29.97 fps, lower field first. Then I burn my DVD in Create Disc using this same MPEG-2 format. I will always watch my DVD's on my TV set, using a DVD player. Based on your post above and my settings and end use, do you recommend I use non-square pixel rendering or square pixel rendering? I have been using non-square so far, based on the Recommended Procedures sticky post and the ULead VS 10+ User Manual's recommendation.

Thanks,

Bryan P.
Florida

TDK1044 · Post by **TDK1044** » Fri Aug 18, 2006 9:50 pm

Hi Bryan,

You are correct in what you have been doing. What John has skilfully done in this posting is to demonstrate that if you capture are working with MPEG2 files, you should uncheck the 'Use Non Square pixel Rendering' box until you are ready to render your entire project. Doing that keeps your MPEG2 files at their highest quality. If your captured files are AVI, then at the point you convert them to MPEG2, enable (check the box)the "Use Non Square Pixel Rendering' feature you have been doing.

jchunter · Post by **jchunter** » Fri Aug 18, 2006 11:00 pm

BryanP,
I agree with Terry.
Since you capture in AVI(DV) format, you should leave Use Non-Square Pixels checked because VS10+ re-renders DV with no visible degredation. The final transcoding to Mpeg2 should also be Non-Square to get the aspect ratio right when you burn the DVD.

sjj1805 · Post by **sjj1805** » Sat Aug 19, 2006 7:09 am

You haven't mentioned the effect of audio/video synchronisation when editing MPEG's.

jchunter · Post by **jchunter** » Sat Aug 19, 2006 3:12 pm

The original report tested Audio/Video sync because we were having an epidemic of OOS (Out Of Sync) problems at that time with Video Studio 8.

Video/Audio sound sync was unaffected by mismatching the Frame Type properties.

My evidence shows that the Audio Video Sync problems in 2004 were caused by a terrible procedural mistake by the Ulead software release team, which actully released at least 5 different (buggy) updates for the Ulead burning engine under the same file name and update designation. (I compiled an Excel spreadsheet of four different combinations of burning engine .dll versions (36 .dlls) that I happened to experience). I'll be happy to email a copy to anyone who is interested.

Every month or so, during the year that version 8 was current, the content of the update file would mysteriously and silently change with no notification to the user base. This caused chaos among users because we could not correlate our testing - we all [may have] had different versions of the burning engine installed, depending on when we downloaded.

You might have noticed that the Audio/Video sync plague abruptly disappeared with the release of version 9.

sjj1805 · Post by **sjj1805** » Sat Aug 19, 2006 5:50 pm

jchunter wrote:...........You might have noticed that the Audio/Video sync plague abruptly disappeared with the release of version 9.

Have you carried out any recent tests? - especially with the inclusion of transitions. My experience has been that when you edit MPEG files you run a high risk of out of synch issues - aggravated when you insert transitions.

Simple straight cuts do not compound the problem tending to suggest there is an issue with the audio overlap - and only when dealing with MPEG files.
This issue remains even in VS9 and VS10+.

The problem would appear to be one relating to program time stamps (PTS) which can be solved by running the file through a dedicated MPEG editor such as Womble or VideoRedo.

If you view the various complaints associated with editing MPEG files I think you will find that the main issue is not video quality degredation but more a case of audio/video synchronisation. This is not a problem when working with DV formats.

jchunter · Post by **jchunter** » Sat Aug 19, 2006 6:08 pm

I recently edited four hours of Mpeg2 HDV with VS10+ with perfect Audio/Video sync every time (transitions, music, overdubs, titles, still jpegs). I have also transcoded to other, more compressed formats such as Divx, Xvid with no A/V sync. issues.