Artifacting and Pixelation!

[T0t]

Hello, I use convertxtodvd to convert all my avi files onto dvd. I normally burn with nero at 2x speed. BUT, I've noticed that everytime I burn a movie ( original avi file around 800 megs on average) it artifacts during the really dark scenes in the movie. You can see little blocks and the colors get really gloomy. The original avi file is most of the time, high quality. Yet, it still artifacts when I play them on BOTH my standalone DVD players. I've tried using various media, the results don't change (currently using Imation 4x DVD+RW media, only media I have available). The encoding option in ConvertXToDVD is set to high, so thats not a problem. please help, thanks!

[guns1inger]

It is the source, for the most part. If you played the same avi on a standalone player with Divx capabilities, you would see the same artifacts. ConvertXtoDVD does not do any filtering, so your avi is simply resized up, and then encoded. This process enlarges and enhances any issues with the source (I know, the source is perfect and doesn't have any of these flaws - wrong). I suspect you will also find that the IRE levels are adjusted to DVD spec along the way, which will also show up the issues in the dark scenes.

What can you do to improve the situation ?

I use avisynth with the blockbuster plugin. I apply the blockbuster plugin before I resize the image to reduce the appearance of macroblocks are artifacts. After resizing I apply the asharp filter to bring back some of the details lost in the resize. I then encode with a standalone encoder, and author the results.

It doesn't get rid of all the issues inherent with extreme mpeg4 compression, but it does get rid of the more obvious flaws. While mpeg4 compression is good, a full movie in 800mb is over compressed, and using about half the bitrate it needs to maintain the image quality of the DVD source. If you squeeze that hard, something has to give. Often it it is in the slabs of subtle colour graduations - darkness, blue sky, plain painted walls etc. that the worst of the problems appear, along with the more usual fast motion scenes.

To put your mind at ease though - burning speed and media quality are NOT the cause of your current woes.

[T0t]

Thank you so much for replying. Does avisynth convert the original avi into another format? or does it just add filters, editing options, etc.? If it just adds filters, can i use avisynth, edit the avi file, then convert that avi file to dvd format using convertxtodvd?

Oh, and if possible(if its possible to simply edit with avisynth, then convert with convertxtodvd), could you link me (or guide me) to a begginers guide for avisynth? adding filters, plug-ins, etc.? its pretty late at night, so if its too much to ask then ill simply look myself. i appreciate any help regardless

[guns1inger]

It's only late where you are

avisynth is a frameserver. It opens video files, processes them, and then passes the results out to another program for compressing. Unfortunately, ConvertXtoDVD does not accept avisynth output, however other mpeg2 encoders do, including freewares ones such as HCEnc.

I would recommend you start by downloading the latest avisynth, Fitcd and AVSEdit. FitCD can produce a simple avisynth file to load and resize your avi for DVD encoding. AVSEdit has the avisynth help files included, so you should be able to pick up the rest from there (over time). Avisynth filters can be downloaded from WarpEnterprises (google)

You could also look at some of the other freeware conversion tools, such as avo2dvd. These will take some of the guesswork out of it if avisynth seems to daunting (and it can).

avisynth can be used for editing (I assume here you mean cutting), but as it is text based, with no visual interface, it can be difficult to get your head around. There are better options available.

LoadPlugin("C:\Video\Avisynth 2.5\Plugins\aSharp.dll")
LoadPlugin("C:\Video\Avisynth 2.5\Plugins\BlockBuster.dll")
DirectShowSource("pathtoavisource.avi")
BlockBuster(method="noise", block_size=8, detail_min=1, detail_max=10)
Lanczos4Resize(688,414,0,0,640,352)
aSharp(2,2,-1,false)
AddBorders(16,80,16,82)

This is a pretty standard avisynth script to resize and filter and avi for DVD encoding. It uses the standard FitCD script as it's starting point.

[Abond]

You may find this tool useful:
http://forum.doom9.org/showthread.php?t=110596
Unfortunately it doesn't use blockbuster.