David Pratt (dp@xxxxxxxxxxx): > >> Note that MPEG1 doesn't have an interlaced mode, so if you record a > >> 640x480 stream from TV input, you'll see artifacts which bleed > >> between the fields. Make sure you're using an encoder which can > >> encode in an interlaced mode (like MPEG2) if you want to capture > >> both fields in a frame. > > To avoid those atrifacts, why not seperate the frame into two fields > to give twice the fps and then compress that video stream, eg pal > 720x576x25fps > 720x288x50fps. On playback every two frames can be re- > interlaced to get the original res/fps. Because each field has a parity. That is, the first 720x288 image is all the even scanlines, and the next 720x288 image is all the odd scanlines. If you interpolate each one up to frame size without taking this into account, the image will jump up and down really horribly and look terrible. I can add this 'functionality' (playback at 50hz without taking into account field parity) into tvtime and then you can see what it looks like. :) > I am involved a project at the moment which has similar requirements > and problems - i need to get dvd quality tv output and the system > wasnt able to report which field it was displaying when i started > coding. I have found that I can get pretty close (although the > interlacing isnt perfect) by using video compressed as described > above, leaving the flicker filter on, and blit-stretching each video > frame to the full display buffer. It looks pretty close although on > some sources the interlacing can look a little stronger than it > should. Are you blitting at the field rate or frame rate? -- Billy Biggs vektor@xxxxxxxxxxxx
