Some questions about interlaced video

[streetsofrage47]

When watching video files on my pc, (a dvd I losslessly converted with makemkv for example) and I check mediainfo about title1 and it will say it is interlaced. But I do not see any "combing" in the movement of the video. Then title2, mediainfo will also say it is interlaced and I will see the combing and turn on the deinterlacer. About 75% of the time when mediainfo says it is interlaced, I will see the combing, but about 25% I see no combing at all. So my question, is mediainfo wrong about interlacing sometimes and the only sure way to confirm is to look for combing with my own eyes? If it says interlaced and I see no combing should I still deinterlace the video for optimal quality?

[jagabo]

Any video can be encoded interlaced. Logically the encoder splits the frame into two fields and compresses each one individually. Upon decompresssion the two fields are woven back together into a frame. With progressive encoding the whole frame is compressed as one image. MediaInfo can only tell you if the video is encoded interlaced. It can't tell you if the frames truly contain interlaced video.