True Interlaced video with Nero Digital

[vigi_lante]

I'm working with a true-interlaced video (DVB MPEG2 Streams). Every time I open a .mpg (mpeg2) file with Nero Recode, the software always recognize it as a progressive video (which is incorrect). So I need to manually select the deinterlace option.

But what I would like to do is keep the video interlaced. Is that a good idea ? The bitrate of the source is about 2400 Kbps. I'm using low bitrates for Nero Digital, like 600-700 Kbps.

I think if I keep the video interlaced, I would not get the same quality, using the same bitrate, right ?

Anyway, what I would like to ask is how I can configure Nero Recode to handle true-interlaced video.

Thanks!

[Manao]

Several things are to be considered :
keeping the video interlaced is only usefull _if_ the display on which you'll watch the movie is itself interlaced. That rules out any computer screens. TVs are, on the contrary, interlaced.
keeping the video interlaced and watching it on an interlaced display will make the motion smoother than if you deinterlaced it.
an interlaced video can be encoded as progressive, and yet shown as interlaced.
an interlaced video is harder to encode than a progressive one ( all other things kept alike ). It becomes even harder when the codec doesn't handle interlaced video ( recode doesn't, so doesn't x264. xvid partially handles it, divx is better yet ).
you can't resize vertically and keep the interlacing


All that leads to the following :
if the display is progressive, no need to think, you deinterlace it before encoding
if the display is interlaced, and that you don't have a lot of bitrate to spare, or if the video isn't high motion, deinterlacing it prior to encoding will improve the perceptual quality ( provided it's properly deinterlaced ), even on an interlaced display. Once deinterlaced, you can downsize it if you're short on bitrate, which will lead to a far more sane usage of the bitrate ( tradeoff sharpness / blockyness ).
if the display is interlaced, and you have bitrate to spare, or if it's high motion, keep it interlaced, even if you encode it as progressive. If you use recode's mpeg4 asp codec, I would strongly advise you to switch to XviD or - better in this case - DivX. If you use the AVC codec, x264 won't offer any better handling of the interlacing, so it's really up to you. In any case, PSNR wise, an progressive AVC codec shoult give better results on an interlaced video than an interlaced ASP codec ( though visually, I don't know which ones would look best, since I never watch videos on interlaced displays ).


Finally, I don't know what player you plan to use to watch the video. It may happens that those players require a correct field order to show properly the video on your interlaced display. Having encoded the video as progressive, the field order "guessed" by the player ( progressive means no field order, so the player makes it up ) might be incorrect, which may lead to the video being completely jerky.

[vigi_lante]

Thanks for your answer. I’m very pleased with your attention.

Speed is my main concern. So, I guess Nero Digital takes a competitive advantage over others codecs. And with the kind of video that I'm encoding, I think deinterlace is a reasonable option, as long it improves the video quality.

[AlexeyS]

keeping the video interlaced is only usefull _if_ the display on which you'll watch the movie is itself interlaced. That rules out any computer screens. TVs are, on the contrary, interlaced.
Can't agree. Interlaced video (for example 50i to 25p) really kills "picture reality" (sports, home video).

[nm]

Yeah, but 50i to 50p would work fine with good deinterlacing. Has somebody tested if H.264-encoded 50p video needs twice the bitrate of 25p (or 50i with a suitable encoder), when the original source is interlaced? Of course motion in the source video has an effect on this, but it would be nice to see some examples of how efficiently modern video encoding techniques can replace interlacing altogether.

Maybe I'll finally set up AviSynth on my Linux system to try this.

[IgorC]

Can't agree. Interlaced video (for example 50i to 25p) really kills "picture reality" (sports, home video).

"picture reality" is called smooth motion. Yes, deinterlace isn't lossless. The picture is really more smooth after it. Maybe it will be usefull to try some filters including different deinterlaces.

[AlexeyS]

"picture reality" is called smooth motion. Yes, deinterlace isn't lossless. The picture is really more smooth after it. Maybe it will be usefull to try some filters including different deinterlaces.
50i to 50p is the only good kind of deinterlace. :)

Any 50i to 25p deinterlacer (even the best) will kill reality effect (that we see in news, sports and home video). 50i to 25p is only good when the original video shooted as progressive.

I'd like to see interlace support in Nero Digital too.

[IgorC]

Ateme and Elecard are preparing their commercial H.264 codecs with interlace support. No info when it will be finished.

[Mug Funky]

Can't agree. Interlaced video (for example 50i to 25p) really kills "picture reality" (sports, home video).
i think what manao meant was deinterlacing 50i to 25p would have an advantage at a low enough bitrate - the screen could decay into a mass of blocks if left interlaced, where a progressive encode might just look good enough to be worth the lost motion and spatial res.

but if your target bitrate is so low it cannot handle interlace, my suggestion is just try to put less stuff on the disc - discs are cheap.

i really wish interlace was supported in x264. ah well. and i didn't realise divX handled it better than Xvid... haven't used the former for a long time. interesting.

[SeeMoreDigital]

I have not used NeroDigital's Recode2 for a while but from what I remember it's unable to generate pure interlaced MPEG-4 video streams from pure interlaced MPEG-2 video sources!

Even if it's able to.... I'm not entirely sure whether there are any MPEG-4 direct-show filters that can correctly decode such streams.

That said, I have been able to generate pure interlaced MPEG-4 video streams using XviD and decode them in a hardware stand-alone player connected to a TV ;)

[vigi_lante]

That said, I have been able to generate pure interlaced MPEG-4 video streams using XviD and decode them in a hardware stand-alone player connected to a TV

Do you know if it's possible to do that using AutoGK ?

[SeeMoreDigital]

Do you know if it's possible to do that using AutoGK ?Sorry I don't know...

If you are able to get access to XviD's encoding features look out for this option: -

http://img55.imageshack.us/img55/6601/xvidinterlacedoption7bu.png

However, you'll need to switch of any "automatic" de-interlacing options AutoGK may have!


Cheers

[Eric G]

I found this thread after trying to create an interlaced MP4 (ASP) with Recode 3, not possible.

Handbrake has no control over mpeg4 options, and cannot enable B-frames. Is there anything else?

[mediator]

I found this thread after trying to create an interlaced MP4 (ASP) with Recode 3, not possible.

Not possible that it's not possible ;)

Can you post some details?

[nm]

I found this thread after trying to create an interlaced MP4 (ASP) with Recode 3, not possible.

Handbrake has no control over mpeg4 options, and cannot enable B-frames. Is there anything else?
Avidemux, if you are looking for a nice GUI. It supports interlaced MPEG-4 ASP encoding with both XviD and libavcodec.