Another Reason Not To Use Cyberlink Decoders

[Taddeusz]

I had this thing bugging me for a while but had never investigated the causes. Basically when I was backing up my movies there would be these odd lines in the videos as if the video were being resized even though I wasn't doing any resizing.

Just as a mental example imagine a diagonal line in the video that is supposed to be perfectly smooth but has a stairstep in it where a line was repeated to scale the video.

So, this morning I decided to finally tackle the issue. The root of the problem comes from the fact that for more efficient compression 1920x1088 is the resolution used for H.264/AVC. The reason for this is that H.264 works best when the resolution is evenly divisible by 16, which 1080 is not. When the video is played back the last 8 lines are simply not displayed which results in a normal 1920x1080p picture. AFAIK, neither VC-1 or MPEG2 require this.

Apparently when used outside of PowerDVD 8 the Cyberlink H.264 decoder doesn't quite work correctly. It decodes the video to 1920x1080 as it should do but then reports the video as being 1920x1088 and in the process the video gets resized to 1088. As a result you get 8 repeated lines from top to bottom on the picture where the video has been stretched to fit 1088.

The Arcsoft Video Decoder filter does not do this. It decodes and reports the correct resolution as 1920x1080.

So, yet another reason to boycott using Cyberlink's decoders as they apparently don't know how to properly report the size of a 1080p H.264 video.