>This makes me wonder: There is a difference >between a clean, high quality stream from a human >perspective and from the perspective of an >encoder (in the sense that is is 'easy' to >encode), is there? If there is no difference, >then there is no point in talking about video >processing that improves video streams >numerically (for encoding), but not visibly.
Yes, there's a difference. A human may not be able to tell the difference between luminosity levels 128 and 129, but the computer can, and if you have a screen that's all 128-level except for lots of 129-level dots spread throughout randomly, the computer is going to waste a lot of space encoding it, and if the pattern of 129-level dots changes every frame, motion-detection will fail too. But it'll all look the same to a human being. From this simple example, one can easily infer that something that looks the same to a human being does not necessarily look the same to the computer. >Many users lack the knowledge to process their >video material in a way that allows mpeg2enc to >get the most out of it. Us developers too :-) I've been working on how to convert the analog sources in my collection (LaserDiscs and VHS tapes) to very clean VCDs/DVDs. It's taken 2 1/2 years. I've had to write a new denoiser, I had to beg other programmers to make fixes in parts of the code, and slowly I'm getting to my goal. >I'm working on a bash script (and a Wizard style >Kommander GUI to control it) for using mpeg2enc, >which features 'source profiles' like 'consumer >DV camera', 'Computer Generated' or 'VHS Tape'. My scripts, and the ones you're generating, should end up as part of mjpegtools, part of some future GUI video-editing system, and as notes in our HOWTO. >If there are general processing methods that are >beneficial for *any* video stream that needs to >be reduced to MPEG, it is desireable to perform >such processing by default. In many cases, the default values strike a balance between quality and speed. For instance, there's no need to make the user pay for "mpeg2enc -4 1 -2 1" until they're ready for it and willing to pay the price. >Perhaps a section in the mpeg2enc manpage about >stream conditioning would help. Sure...as soon as we know how to do it :-) >>I'm not quite sure though what is meant by >"numerical conditioning". > >Any processing that has no visible effect, only >numerical. y4mdenoise run at very low tolerances ("-z 1 -t 1" or "-z 1 -t 2") qualifies as such processing. Steven Boswell ulatekh at yahoo dot com __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/ ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users