On Tue, 10 Jun 2003, Steven M. Schultz wrote: > Hi - > > > From: Selva Nair <[EMAIL PROTECTED]> > > As the source is progressive ppm frames, better keep it that way. > > Use -F 24000:1001 and encode with pull down flag: > > Well, as it turns out it seems that the encoder is "doing the right > thing" for me (despite my being confused ;)). > > I remembered I had a copy of 'dvdview' installed and using that I can > see that mpeg2enc is generating 'top field first' :
But why do you care about top_field first when the source is progressive? If you use 24000:1001 and pulldown instead of 30000:1001, the encoder will keep switching between top_field_first = true/false to generate the pulldown sequence. > > PictureHeader: > temporal reference: 3 > picture_coding_type: B > vbv_delay: 65535 > fullpel forward mv: false > fullpel backward mv: false > fcode[0][0] (fw/h): 3 > fcode[0][1] (fw/v): 2 > fcode[1][0] (bw/h): 4 > fcode[1][1] (bw/v): 3 > intra dc precision: 9 > picture structure: frame picture > top field first: true > frame pred frame dct: false > concealment mvs: false > q-scale type: 1 > intra vlc format: 1 > alternate scan: true > repeat first field: false > chroma420type(obsolet):0 > progressive frame: false > > This does raise the (idle) question of how would one create > a MPEG-2 progressive encoded movie? HD-TV can use 1280x768 > progressive as one of its resolutions. By progressive if you mean progressive_frame flagged as true, again, use 24000:1001 and pulldown you will have it. But if you want a progressive sequence the dvd preset wont allow it as DVDs are for interlaced displays by design. I think mpeg2enc will generate progressive sequences with a generic mpeg2 preset plus -I 0. > > > I would use -S 420_mpeg2 at the ppmtoy4m stage instead of > > resampling by y4mscaler as above. > > Why? I have to rescale from 720x540 to 720x480 which means going > thru y4mscaler. Seemed logical to have it do the chroma conversion > at the same time. You have the full 444 chroma info at the ppm stage so isn't it best to subsample it directly to 420_mpeg2 from the ppm? Otherwise you go through 444 -> 420_jpeg -> 420_mpeg2 -- looks more lossy to me. Selva ------------------------------------------------------- This SF.net email is sponsored by: Etnus, makers of TotalView, The best thread debugger on the planet. Designed with thread debugging features you've never dreamed of, try TotalView 6 free at www.etnus.com. _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
