What is "Half D1"?

[Brian]

Archived from groups: rec.video.desktop (More info?)

I've seen people talking about this setting in the video newsgroups
for recording a VHS tape to DVD.
Could someone please tell me what Half D1 means.

Regards Brian

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

Brian wrote:

> I've seen people talking about this setting in the video
> newsgroups for recording a VHS tape to DVD. Could someone
> please tell me what Half D1 means.

"D1" (or "D-1") is a professional, digital VCR system. It
stores the data on the tape in uncompressed 4:2:2 YCbCr
format, using exactly the same type of 13.5 MHz sampling
(and, consequently, exactly the same pixel aspect ratio
and resolution) as on which the legal DVD resolutions
are based. See <http://www.broadcaststore.com/store/
model_detail.cfm?id=5167> for one example of such VCR.

The "D1" format in itself is based on a standard called
ITU-R BT.601 (or, as it was formerly called, "CCIR Rec.
601".) The legal DVD resolutions are, likewise, based on
the same standard.

However, the D1 VCRs were the first to implement ITU-R
BT.601 in practice, so the name stuck, and many people
now talk about "D1 resolution" when they mean 13.5 MHz
4:2:2 sampling in general sense.

The DVD resolutions which correspond to the "D1 resolution"
are 720×576 (or 704×576) for 625/50 ("PAL") systems and
720×480 (or 704×480) for 525/59.94 ("NTSC") systems. The
"half D1" resolution is simply half of that in the
horizontal direction: 352×576 for 625/50 ("PAL") systems
and 352×480 for 525/59.94 ("NTSC") systems. (The pixels
in these so-called "half D1" resolutions can be thought
of as being double-wide when compared to the "normal"
DVD resolutions.)

These "halved" resolutions are defined in the official DVD
standards, and should be playable on all DVD players, even
though the authors of commerical DVDs do not usually use
them much. You can use them to save space on a disc when
the-material-to-be-encoded does not necessarily warrant
the full horizontal resolution.

* * *

You might also want to take a look at my page on digital
video resolutions and pixel aspect ratios:

<http://www.iki.fi/znark/video/conversion/>

--
znark

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

> I've seen people talking about this setting in the video newsgroups
> for recording a VHS tape to DVD.
> Could someone please tell me what Half D1 means.

It means using a resolution of 352 x 480/576 instead of full D1, which is
720 x 480. Half D1 is useful for VHS->DVD, because VHS's horizontal
resolution is generally considered to be around 360. That's not completely
accurate, though, as VHS is an anlog format and doesn't really translate
into pixels the same way a digital format such as MPEG2 does, but for all
intents and purposes that's the rule most people go by. The obvioys benefit
is that you can get away with a much lower bitrate, and it's much faster to
encode.

You can also use 352 x 240/288, which is even closer to VHS, but it doesn't
work particularly well with interlaced material, which is what most people's
VHS material is.

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

"Allan" <fghj@tyui.tyu> wrote in message
news:cfvuqv$1er$1@sparta.btinternet.com...
> > I've seen people talking about this setting in the video newsgroups
> > for recording a VHS tape to DVD.
> > Could someone please tell me what Half D1 means.
>
> It means using a resolution of 352 x 480/576 instead of full D1, which is
> 720 x 480. Half D1 is useful for VHS->DVD, because VHS's horizontal
> resolution is generally considered to be around 360. That's not completely
> accurate, though, as VHS is an anlog format and doesn't really translate
> into pixels the same way a digital format such as MPEG2 does, but for all
> intents and purposes that's the rule most people go by. The obvioys
benefit
> is that you can get away with a much lower bitrate, and it's much faster
to
> encode.

In addition... Half-D1 is useful no matter what the source resolution if you
are trying to conserve storage/bandwidth. It allows lower bitrate encoding
while reducing artifacts at the expense of sharpness of the image.

 

[netrate]

Does anyone know how to get D1 Half resolution fora SONY VEGAS project? I have finished the project and now I want to render to Mpeg2 (to DVD) and I need the file size to be small so I can put as much on it as possible...any ideas on the project setting and the render settings?

 

[GermanScheisse]

You need to specify a pixel aspect ratio of 2.2348 which is a result of the following expression:
(59/54)*(720/576)*(576/352) = 295/132

Source: http://www.mail-archive.com/mjpeg-users@lists.sourceforge.net/msg02479.html (Please note that the guy was correct in his first calculation, the replies were incorrect).

I've tested it for the same purposes of digitalizing my VHS's.

 

[Mousemonkey]

This topic has been closed by Mousemonkey