What are the pros and cons of interlaced video on for you ?

[djidjo]

Hi folks, this is a question for everybody. I'm new to SVCD encoding and already did a few tries. I'd like to know what are the pros and cons for interlaced video on SVCD (on TV screen of course).

PROS of interlaced video (for me) :
- big pro : film is MUCH smoother ! (50 fps in PAL instead of 25)
- spare the deinterlace processing time (when video is captured from VHS)

PROS of deinterlaced video :
- still image is stable (useful when playing still pictures from an interlaced animated movie)
- no problem with all the "top/bottom field first" stuff.

As you can see, I see no big "pro" for deinterlaced video when watching it on tv screen. But since I see many people deinterlace the video before encoding it to SVCD, I'm still wondering...

Thanks in advance for your opinion !
Djidjo

[avih]

if your source material is truely interlaced, and you find the smoother playback much more enjoyable (as myself), than indeed, interlaced is the only 'correct' method.

however, if you reduce the frame size, or deinterlace, you may achieve better compresibility. also, not all the sources are truely interlaced (as film sources are usually not interlaced). also, atm, it's a bit hard (although possible) to play interlaced clip on a pc monitor (and a pc player) and get this 50fps experience.

buttom line: the one that looks best for you (you'll have to try both methods, and their variants as image size etc) is the best for you. period ;).

if i try to stay objective, the most correct way to make svcd of true interlaced material is keeping it interlaced.

cheers
avi.

[Pko]

The biggest "con" of maintaining true interlaced video when "SVCDing" it is that the interlaced version compresses usually much worse than the deinterlaced one, so if you do not have enough bitrate the usual MPEG artifacts associated with low bitrate will appear.

So if the source is full frame (usually is since interlaced material is filmed for TV and so its AR is 4:3) and somewhat difficult (noisy, or with bad lightning or non-steady, and usually all DV material is has the three at the same time), I decomb it even when encoding at full 2600CBR.

Of course, the decission is totally subjective, since I find more annoying the MPEG artifacts than the deinterlacing artifacts (and the less-smooth playing). Of course, I could do some king of "smart" decission for each fragment of video, keeping some interlaced and deinterlacing others, but it is too much work for me :-)

For good professional-made filmings (those captured from TV, for example), I keep the interlacing.

[djidjo]

Thanks for your replies. This bring me new questions : :)

to avih :
you say "not all the sources are truely interlaced (as film sources are usually not interlaced)". What do you mean ? All videos I recorded so far were interlaced, both from Hi-8 and VHS. They were all home-made videos, so you mean cinema films are usually not interlaced ? I have to try and see...

to Pko :
- decomb = deinterlace ?
- "the usual MPEG artifacts associated with low bitrate" = ugly blocky video ?
- 2600 Kbps is the Max for SVCD ? If it's higher it's XSVCD, right ?

By the way, what's your favorite deinterlace App/filter ?

Thanks
Djidjo

[avih]

to understand better what 'interlaced' means, either read more threads on this issue on this forum, or (recommended anyway) read 'Luke's Video Guide', including the interlaced section at http://www.lukesvideo.com/

cheers
avi.

ps.
home videos are usually true interlaced content.

[Pko]

to Pko :
- decomb = deinterlace ?
[/B]
Yep
- "the usual MPEG artifacts associated with low bitrate" = ugly blocky video ?
Yes, but also some "washing" around edges, "muddled" colors... is not easy to explain, but take any DVD and encode a section at 720x480 with a bitrate of, say, 500Kbps and you will see for yourself... In sections with lots of movement you will see blocky video, but in sections more steady you will see also many digital errors that are not really blocks, but are also very annoying
- 2600 Kbps is the Max for SVCD ? If it's higher it's XSVCD, right ?

2600 is the standar's absolute maximum for video in SVCD, but you must then use 160 or less for audio.

By the way, what's your favorite deinterlace App/filter ?

Decomb.dll :-)