On Tue, 12 Sep 2006 16:51:37 -0700, Phil Ehrens wrote:

>> Does anyone know if VCDs are interlaced? All DVDs, no matter PAL or NTSC
>> formats, are all interlaced, correct?
>
> VCD's are interlaced...

I thought so. Hmm, that means the traditional transcode agent mpeg2enc doesn't support VCD creating then, since VCDs are encoded as MPEG-1. correct? Ref:

**ERROR: [mpeg2enc] Interlaced encoding (-I != 0) is not supported by MPEG-1.

> Many recent NTSC dvd's are progressive 24fps, but a surprising number of
> NTSC dvd's are interlaced...

hmm… I read "even non-interlaced video will be written interlaced on the dvd" [1], now I've confirmed that it is wrong. Progressive 24fps? interesting, any luck to have burnt such DVD anyone? How did you do that, say we are converting from a 23.976fps avi? I remember when tried encoding without pulldown, I get the following when doing the dvdauth:

not a valid DVD frame rate: 24000.0/1001.0 (NTSC 3:2 pulldown converted FILM)

thanks

[1]avi to dvd converter http://www.linuxquestions.org/questions/showthread.php?s=&threadid=295947

> not a valid DVD frame rate: 24000.0/1001.0 (NTSC 3:2 pulldown converted
> FILM)

Same problem here, I could never figure out how to get 24fps to work on an NTSC dvd either, though it would be great to be able to. I just make everything 30fps. BTW, every 24fps feature I have seen has had a short chunk of 30fps at the very beginning, but I can't see how that could qualify as any sort of "trick", I think it's just that the distribution companies all do their logos at 30fps.

By the way, I often see Chinese dvd's where there is a deluxe Hong Kong release at 24fps, and then a bunch of *ahem* other releases that are all at 30fps, and usually one with the interlacing backwards or sideways for good measure. There is also often one dvd that is "recovered" from a vcd that is a total throwaway.

Phil Ehrens

>> not a valid DVD frame rate: 24000.0/1001.0 (NTSC 3:2 pulldown converted
>> FILM)
>
> Same problem here, I could never figure out how to get 24fps to work on an
> NTSC dvd either, though it would be great to be able to. ...

Found a good reference at

http://www.allformp3.com/dvd-faqs/34.htm

Seems quite complicated. Here is the extract:

,-----
| ... MPEG-1 CBR and VBR video is also allowed. [...] NTSC, 29.97 interlaced
| frames/sec and PAL/SECAM, 25 interlaced frames/sec video display systems are
| expressly supported. Coded frame rates of 24 fps progressive from film, 25
| fps interlaced from PAL video, and 29.97 fps interlaced from NTSC video are
| typical. MPEG-2 progressive_sequence is not allowed, but interlaced
| sequences can contain progressive pictures and progressive macroblocks. In
| the case of 24 fps source, the encoder embeds MPEG-2 repeat_first_field
| flags into the video stream to make the decoder either perform 2-3 pulldown
| for 60Hz NTSC displays (actually 59.94Hz) or 2-2 pulldown (with resulting 4%
| speedup) for 50Hz PAL/SECAM displays. In other words, the player doesn't
| "know" what the encoded rate is, it simply follows the MPEG-2 encoder's
| instructions to produce the predetermined display rate of 25 fps or 29.97
| fps. This is one of the main reasons there are two kinds of discs, one for
| NTSC and one for PAL.
`-----

T

documented on: 2006.09.15