October 9th, 2003, 03:36 AM
SVCD problem on DVD player.
First of all, this is probably pretty irrelavent to anything that has to do with security but i trust people around here for good input and help even though 90% of my threads are a huge flamefest and i get negged. anyways the svcd i made with nero works fine with my dvd player but the quality like pulses from good to bad. like every second its just pulsating from clear to blury and pixelated.
October 9th, 2003, 03:38 AM
hey ..i dont have the answer but you might wanna ask that question here http://www.dvdrhelp.com/ or here http://www.network54.com/Hide/Forum/70438 since this is their field of knowledge
October 9th, 2003, 04:32 AM
I think this thread would be more suited in General Chit Chat or even Hardware. You might also want to ask in the following forums that are more suited for this questions.
October 11th, 2003, 02:19 PM
I will recomnd moving to Hardware asap
October 11th, 2003, 03:07 PM
To answer the question.....
What you're seeing is an artefact of a bad MPEG compression.
MPEG video is compressed both spatially (within a single frame like a JPEG image) and temporally (between frames). Instead of encoding the full content of each frame, MPEG saves space by encoding only the changes between frames. For this, it uses what's called a GOP (group of pictures) to define each frame of the video an an I (key), B (bidirectional), or P (predictive) frame.
Normally, a GOP begins with an I-frame and then has 11-17 compresseed B and P frames , then the cycle starts over with a new GOP and I-frame. A normal GOP contains anywhere from 12-18 frames. But because B and P frames are much more highly compressed than I-frames, if you use a longer GOP with more B and P frames, you can achieve much higher compression. The problem is that the further you get from an I-frame, the lower the quality will be.
If you have a 24 fps video and use a GOP length of 24, there will be a new I-frame precisely once per second. The picture appears sharp on the I-frame, then becomes gradually more blurry over the next 23 B and P frames, then suddenly becomes sharp again with the new I-frame of the new GOP. This is what you are seeing as a pulsing effect. If the MPEG was also encoded with a poor quantization matrix, you may also see macroblocks that come and go over the course of the GOP.
For more information about MPEG encoding, I recommend http://www.kvcd.net. Kwag and company are on the absolute cutting edge of MPEG compression.
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