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playing interlaced footage like in tv
When playing interlaced footage using standard players such as VLC or Winows Media Player we get always 25 frames per second. The only freedom is we can choose a deinterlace method (which basically blends two frames into one) or play 25 (PAL) frames consisting of two half fields each.
When we watch broadcast tv, we get 50 frames (half frames), which gives us feeling of fluent motion. Is there any player which plays video exactly like in broadcast tv, so we get these 50 half frames, not 25? On a standard LCD screen.
thanks for answer
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8 Replies
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I think you have to have a CRT monitor to be able to see that, since LCD monitors are progressive scan.
http://www.scenethroughglass.com
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I haven’t used VLC, but Media Player Classic (MPC) can use GPU accelerated deinterlacing which appears to give 50 output frames/sec for 25i input.
I also use ffdshow’s deinterlacing with MPC, and ffdshow offer several deinterlacing methods including motion compensated interpolation to give proper 50p output from 25i (or 60p from 30i). This is probably the sort of thing that higher-end LCD TV are doing, and looks very fluid and smooth.
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But is there any way not to deinterlace and just watch 50 half frames? Like in TV? This shouldn’t be a hard task for the computer, just to show 50 frames, upper and lower field in sequence.
Now most of tv sets ain’t CRT, but LCD, so it should be a problem?
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Theoretically yes, it’s just a matter of displaying each field (half of an interlaced frame) in succession at 50 (or 60) fields per second. But interlacing was designed to suit CRT TVs, which are scanned one line at a time in two passes (hence the flicker from any CRT TV). If you try to do this on an LCD you either get a jittery image or half the vertical resolution, so some clever image processing (the deinterlacing) is usually done in the TV to merge the 2 fields into 1 full frame. PC are quite capable of doing the same type of thing, but it’s usually done in software by the player, and there are many ways of doing it.
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OK, but what with LCD TV sets? They are also capable of processing interlaced signal and are not CRT based? These days we don’t own CRTs, they are rather at waste dumps. I would like to see 50 half frames on my LCD. Is there any way I can do it on a LCD monitor?
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In the case of LCD TVs, they are doing deinterlacing in an image processing chip that typically produces one full picture from each video field, so you are seeing 50 progressive pictures per second (50p).
You can do a similar thing in software on your PC. I don’t use VLC, but I believe it has a variety of deinterlacing modes. Look for deinterlace methods called “doubler” or “yadif” – they will give you 50p from a 25i source. Try them all to see what you like best.
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Update:
https://wiki.videolan.org/Deinterlacing
Looks like there are lots of deinterlacing options in VLC… try Yadif 2x -
thanks
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