Interlaced Input

Dealing with interlaced input

Most of cameras today provide interlaced content. If you output the video with progressive display, it can produce artefacts. Interlacing can be regarded as a disadvantage. On the other hand, it also brings some adventages, either. For instance, double field rate which is advantegous especially for 25/50 FPS. In any case, if you intend to display interlaced content, you may need to use some additional actions.

Deinterlacing

Simple way of getting rid of interlacing artefacts is deinterlacing. It can be toggled for both OpenGL and SDL displays by pressing 'd' key when playing video or as a command-line parameter:

uv -d sdl:d uv -d gl:d

With all display, you can use postprocess filter deinterlace:

uv -p`` ``deinterlace -d 

The only difference is that with the postprocess filter you cannot toggle deinterlacing on runtime.

Doubling frame rate

Advantage of using interlaced video is that it has double field-rate than its progressive counterpart. The advantage over progressive video is that the movement is usually more smooth. UltraGrid can emulate the behaviour of interlaced systems by doubling frame rate and interlacing individual fields in manner of television systems. If you want this behaviour, add a command-line parameter -p double-framerate. Note that you probably obtain best results if you set display refresh-rate to multiple of video frame/field rate, eg. 50 or 100 for 50i video, eg. 60 or 120 for 59.94/60 interlaced video.

uv -d sdl -p`` ``double-framerate

Note 1: You shouldn't enable this option if the video is progressive or progressive segmented.

Note 2: Even if you use this feature, you may also want to use normal deinterlacing (-d gl:d or -d sdl:d) to mitigate interlacing artefacts.