Just Trying out the Panasonic encoder(demo version)and while the quality is not bad, distortion occurs whenever there is hi motion in the video. I'm trying to convert an MJPEG (avi)file, i created with a Matrox G400 TV card, to mpeg1. There is myriad of settings on the panasonic encoder and being new at this i'm not exacty sure where to begin as far as reducing this distortion. I am relatively new to video capturing and any help would be greatly appreciated

j4j

-- james forney (j4j2000@home.com), May 09, 2001

Answers

Even with the best h/w or s/w encoders really fast motion will produce blockiness in MPEG-1 streams and there is only so much one can do to reduce it. This is why MPEG-2 was created. Anyway, in Panasonic, you can try half-pel instead of full-pel. Alternatively, you can go through the tedious process of reviewing your original AVI clip frame-by-frame, and noting where the scene transitions are or where the fastest motions occur. You take note of the frame numbers, and in Panasonic there is a feature where you can force the inclusion of I-frames at the start of new scenes, or force I-frames all throughout fast-motion scenes. At the start, you can also use a lower number of frames for the GOP and less frames for the B and P intervals instead of the default 15,3,3 for NTSC and 12,4,x for PAL. It is in all these that TMPGenc, which is freeware so far, simply outclasses Panasonic. For example, in TMPGenc you can activate the "force I-frame at scene changes" feature and it works reliably. And for creating VCD MPEG-1 streams, there is a whole raft of intelligent de-interlacing features that simply provides smoother yet sharper video than Panasonic, which only has "choose frame A or B or de-interlace (which we don't know exactly how it does it)". I have an earlier Marvel G200 capture device that I use sometimes; I always use full resolution 704x480 when capturing.

-- Mehmet Tekdemir (turk690@yahoo.com), May 09, 2001.

Thanx for your response Mehmet! a better description of the distortion i get would be not necessarily hi motion, but any motion at all(such as a person walking across the room etc.)will create thin horizontal lines and the moment the scene is relatively still they dissapear. My original AVI file is crystal clear so i'm sure thats not the source of the distortion. I will try your suggestion! and any more additional recommendations would be appreciated. Thanx again

j4j

-- james forney (j4j2000@home.com), May 09, 2001.

The thin horizontal lines you see may be the result of playing back your clip with the wrong field order. Or during encoding Panasonic reads it in the wrong order before interpolating. VCD MPEG-1 only has 240 lines; the easiest way to get this from a full 480-line interlaced source would be simply to use one field and discard the other, which is one way Panasonic does its job. There is also a choice of interpolation but I can't remember if there is a way of choosing whether to read the odd field first before even (or field A before B) or vice-versa and a way of previewing or verifying it. In contrast, TMPGenc has all that and more: you can preview the interlaced AVI file source and reverse the field order if on preview you see jerky motion or these horizontal lines (others might call these jagged edges), and choose to adaptively interpolate the two fields (instead of simply discarding one) into one composite smoother field which looks better than any of the fields alone.

-- Mehmet Tekdemir (turk690@yahoo.com), May 10, 2001.

Sounds like interlacing. What resolution did you capture at? If you captured above 352x240 then you need either have panasonic deinterlace the file or setup a frameserver with virtualdub and use the one of the deinterlace filters.

If you have a decent CPU and a good amount of HD space, there are ways to get much better results from that card, using all free sotware too.

-- Sean (sean_hatfield@hotmail.com), October 30, 2001.