Question about deinterlacing

[wopeipeipei]

Hi, here I have a newbie's question about mpeg4 video deinterlacing.
My question is: When is deinterlacing done? I mean, is it done when you creating the mpeg4 video or you need a seperate(or maybe built-in) deinterlacing filter while playing back? I noticed that the divx 6.xx decoder has built-in deinterlacing stuff but I am wondering what deinterlacing method it is using, motion blur/bob/...?
And another thing I am intrested in is that is there a deinterlacing filter built-in with xvid decoder? If not, what is the best free deinterlacing filter I can get?

[Teegedeck]

It is always recommended to deinterlace before encoding because firstly deinterlacing on playback is never that good, secondly interlaced material usually takes up higher bitrates.

Some MPEG4 codecs can encode interlaced material, none deinterlaces content before encoding by itself, some feature some kind of deinterlacing-on-playback add-on.

XviD can encode interlaced material with its interlaced-option but it cannot deinterlace on playback.

So, deinterlace using an AviSynth plugin like tdeint, kerneldeint or tomsmocomp.

[Didée]

It is always recommended to deinterlace before encoding because firstly deinterlacing on playback is never that good, secondly interlaced material usually takes up higher bitrates.
"It is always recommended" is too much a generalization. It depends on what viewing method on is aiming for. When the input is true video content, and playback is planned on PC monitor only, then plain deinterlacing is a common option. But if motion fluidity is really important, things change. For viewing on an interlaced display device, the interlaced structure should be kept then, and for progressive display devices either the same ("reduced" quality with realtime bobbing during playback), or hi-Q bob-deinterlacing before encoding is adviced.

My favourite example is Michael Flatley's "Lord of the Dance" show. I did that one in all three modes - interlaced for reviewing on TV, bob-deinterlaced for PC-only playback, and "simple" deinterlaced to show up how much you're loosing when not using the first two options. ;)

[wopeipeipei]

I have been using bsplayer/zoomplayer and xvid/divx decoder for mpeg4 video play back and never noticed any interlaced video during playback(I didn't know that there is something called deinterlacing at all at that time...). But after I changing to KMPlayer with it's built-in decoders(libavcodec) for playing back these days, I found something strange:
1. When playing "From the earth to the moon" dvdrip with KMP deinterlacing off, I got interlaced video sometimes. Does this mean that the deinterlacing setp was missing when they rip the DVD?
2. After turning deinterlacing on(ffmpeg deinterlacing), the interlaced video is gone but it seems that video quality was cracked up by jags especially for those parts that contain lots of details. Is this caused by the deinterlacing filter?

[setarip_old]

When playing "From the earth to the moon" dvdrip with KMP deinterlacing off, I got interlaced video sometimes. Does this mean that the deinterlacing setp was missing when they rip the DVD?What software and procedures did you use when you ripped your original, purchased DVD?