De-interlacing DVB MPEG2

[snoddas]

Hi,

I have a couple of DVB TS captures. Most DivX/XviD and WM9 guides are great, however, I find them lacking when it comes to deinterlacing info.

What codec is the best to use if I want to retain the 50fps feeling (by encoding the 25i MPEG2 to 50p)? Preferably I'd like to have my 720x576 video in the same res but I understand that it would have to be atificially interpolated to keep the resolution, so, a lower res is ok (perhaps 720x288 is possible? - stretching the video during playback to a normal aspect ratio)

My question is then, *what are your experiences* when using deinterlacing, I know all codecs handles it but which codec handles it best?

PS. I want these "live sports" 50 fields/second files for computer playback, that's why I want to deinterlace them.

thanks,
all input is welcome!

[cweb]

But it isn't really at 50fps (all the transmissions I know of so far)...

I myself deinterlace with kerneldeint using avisynth , keeping the stuff at 25fps which it really is (not 50fps), either into a KVCD or a Matroska file with the XviD codec and Ogg Vorbis audio.

[snoddas]

Hi cweb,

no, live transmissions (sports, studio etc.) are transmitted in the same format as films,they're 25 interlaced fps but live transmissions have different information in the 2 fields of a frame.

I'd need 50 progressive fps to convey all the information in a 25i signal. The "windows media encoder 8" GUI is the only encoder I know of which had options for this.

[snoddas]

Another thing that surprises me is that if you play back live content in MPEG2 (e.g. insert such a 25i DVD in a PC DVD-ROM) the player (or codec perhaps?) will deinterlace it extremely well upon playback in PowerDVD, WMP etc. (it will look like playing back 50 clean fps!)

However, if I encode a DivX, Xvid or WME clip in 25i out of this MPEG2 source (maintain the interlacing), the playback of this new file won't be deinterlaced automatically in WMP/BSplayer etc.

[symonjfox]

Imho, you should encode the file (to Divx or Xvid), keeping the interlaced source, and enabling the interlacing option in the codec. This will encode both fields separatly and will keep the interlacing artifacts off course.

On playback, MPEG2 uses PowerDVD direct show filter, so it deinterlaces interlaced contents, but Divx or Xvid don't.
If you want to try, use lastest FFDshow and enable Deinterlace option. It works pretty fine (of course an interlaced content is better when seen on a interlaced monitor ex TV).

[snoddas]

Thanks symonjfox! That did it for me!

A big wet kiss to you.. :D

BTW: Do you know why DivX and XviD don't deinterlace automatically? Can they be made to? Does WME9+WMP deinterlace automatically if I encode it properly in WME9? Any other info here?

On deinterlacing in ffdshow: I find that all settings except DScaler suck..
I tried all the settings after which i downloaded and installed DScaler, using the DScaler-Greedy setting (greedy .dll). Much better than all the options in ffdshow (most of those ffdshow settings don't deinterlace at all it seems..). What are your impressions and tips on this, any favourite setting?

[symonjfox]

Originally posted by snoddas
BTW: Do you know why DivX and XviD don't deinterlace automatically? Can they be made to? Does WME9+WMP deinterlace automatically if I encode it properly in WME9? Any other info here?
Easy, because they're CODECS, they just Encode / Decode streams. They don't deinterlace anything (or better using Divx you can deinterlace, but this process is done before the real encoding).

Imho, interlaced content should be encoded as interlaced! Deinterlace it just on playback (ffdshow). Because keeping the video interlaced, you will keep much more quality; and I think that anyone of us will get a MP4 standalone (one day or another) so if we deinterlace we throw away some particulars in the original video forever.

[unixfs]

Uhm,
when I watch interlaced mp4 content encoded from an interlaced mpeg2
dvb stream, my mp4 standalone shows a much worse picture
than the corresponding deinterlaced one.
In the former case I see persistent combing.
Maybe it's just my old TV that sucks.

[symonjfox]

Well, I don't know. I only know that reality is going strange in MPEG4 area.
for example, when DVB arrived, there were MPEG2 hardware decoders; when DVD arrived, there were DVD players (that use MPEG2 hardware decoders). And both were stable and quality depends on source encodes.
MP4 standalones are very unstable, they work, they may work, they don't work with particular material. Then some support all features, other just few ones ... It's just a big confusion.

Maybe your standalone can't handle interlaced material as well. Or maybe you need a firmware update ... who knows?

In fact I'll wait to buy a standalone until I'll see a full working one (Divx Xvid 3ivX and generic MP4 ASP, with HE AAC audio)!

[cweb]

Especially when encoding KVCD (optimised mpeg1 matrix), I deinterlace the DVB-S mpeg2 recording. The results are great (ok it depends on the quality of the transmission). Also there is no need to deinterlace on a PC, and the quality is better than 'not deinterlacing' (and mpeg1 can't be used to store an interlaced recording).

I have not found any difference between movies, live sports etc. All were classical 25 fps interlaced PAL. But YMMV and it will depend on the stations involved.

[symonjfox]

Off course, MPEG1 has no interlacing support, so the only way to use it is deinterlace the original (or half the vertical resolution 576 -> 288).
MPEG2 and 4 have support for interlacing, and, IMO the quality is superior than deinterlace one (depends on where you're watching).

On a TV (using TV out or standalone) interlaced material shows more details and more natural moviments.

On a PC monitor, non interlaced material is better (and gives more compressibility).