 I am against converting DAT/mpeg to avi
I really disagree converting a .DAT/mpeg file into Divx/xVid .avi file. Divx/Xvid got so popular in last few years because they compress a 4.47GB (2hr video) dvd into 700MB to 1GB avi file, while the quality is reduced only 10% to 20%. This is a huge space gain trading off small quality. One cane reduce the size to 300MB, but quality will drop to 20%, not watchable. There is an optimal limit on how smaller you can make a certain video file without compromising the quality.
In DVD movie format, video contains much more detail video data for each frame. Data-structure is not that complex to support regular Home DVD players. Divx/xVid discards redundant frame information and uses complex algorithm to store the same video in compact form. Thus resulting video file size is so small.
In VCD or mpeg, video is already compressed AND/OR optimized for playing in DVD/VCD/PC. An mpeg file does not contain extra information for every frame, it is already using compact data-structure to save space. If we apply divx/xvid on a .dat/.mpg file, file size will be smaller but, it will loose many potential information about each frame. Resulting in bad quality avi. NO conversion can produce better quality than the source video.
There can be cases where a xvid/divx file of a dat/mpeg is much smaller size and quality is not too bad. It can happen if the scenes are less changed, like two person just talking, nothing else is moving. But if any other kind of video, like action or 69/51 borti where scene changes frequently, divx/xvid conversion won't be able to preserve quality if file size is reduced.
What I said is my opinion based on my knowledge and practical experiments. I always look forward to watch good video, good quality video. It may be few hundreds Megabyte more, would take few more hours to complete download, but once I download the video, I have it for lifetime. Converting an 1Hr dat/mpeg file (600MB) would take around 2hours, resulting in around 450MB avi file (File size can be lowered but quality will be absent). @15KB/S speed it would take me 2.8HRs more to download 600MB file instead of 450MB.
Divx/Xvid is not a magic that makes the file smaller. It's simple computer program that discards redundant video information and saves the frames in compact data-structure. Now days some DVD contain 4/5HRs video in a 4.47GB disc. This video is already compressed, divx/xvid can't make it smaller and keep the same quality. Same goes with Dat/Mpeg, they are already kind of compressed. Making .avi we are just converting the format, not reducing file size maintaining the quality. Moreover, if it is released as DAT/mpg some user can make it VCD easily. __________________ Hello, R U CDng? |