DvD movie quality vs home grown quality

[schematic2]

Why is it that a store bought DvD can get perfect video quality on a 2 hour recording, and we can't. Is their encoding better than whats available to the homeowner?

Thanks

[geek rock]

simply put, yes.

they can afford to spend millions of dollars on DVD encoding software and hardware - that and the fact that their sources are of better quality than ours anyway. (ie, broadcast tapes, film stock, etc).

-Mark

[snafu099]

Will not ague the point, just that I can not tell the differance when played on my 27" tv. The quality looks the same to me.

Using ADS usb InstantDvd-2

O.K. , if I pause at one of those specal frames and zoom, zoom to max, I may notice "some' differance, but not in normal play

[vhelp]

Depends on a few other factors too.

First, you didn't way what your source is, when you compared DVD to your
home-brew (or homeowner)

If you home-brew is from a CAM source, then you have to also ask of which
cam, DV or lower. In any case, lets assume DV, and that that's your comparison.

* DV is Interlaced. That's 720 x 240 (240 fiels * 2 = 480)
* poor quality around horizontals (view text to see)
* 720 is the max resolution (Cinema goes FAR beyond that)
* lens size
* lighting
* noise levels (in all areas)
* professional camera men
* fps (ie, 24 vs 30)
* color space (too low on home-brew cams)
* much much more.

When you're dealing w/ Cinema cams and professionals, its night 'n day
difference.
ie, widescreens DVD's are 852 x 480, but your cam is 720 x 480.
It's just impossible to onbtain the same level of quality (when dealing w/
home-brew DV cams.. Plus, you're not a pro at your CAM and other things)

If you're talking about capturing from cable or satellite, for instance, then
you can forget about it even more so.
.
.
TV is another color space (is lower) and it's an encoded source too. That
means you'll get macro-blocks, noise, and other artifacts, of which you will
be re-encode from. Plus, you're not a pro at encoding (obviously)

With DVD, the source is first-time originals. No noise, and no encoding is
done at the source level. When it's processed, then only encode it once, to
MPEG-2 (hence, DVD) and as such, there are no issues to contend to. So,
in a sense, the sky is the limit for them that deal w/ these sources.

Assuming DV here..
Now, you could look at your DV source as originals, but you also have to
consider that your DV source is already tainted. It's ben compressed, and
de-color spaced, and so on and so forth. Resolution is lower, only 720, and
to make matters worse, it's Interlace, and only 240 lines. That's why the
horizontals look awlful. And, if you de-interlace, they really look bad. Thats
why people say leave it Interlaced, because you have a better chance at
obtaining the maximum out of your cams limitations.

Now, take for instance, your DVD...
You rip it, and re-encode it. hmmm.. So, why does it look better than those
sources that you capture from cable or sattelite from ???
Well, for one, again, Noise. And that could be from many factors. Also,
the DVD is crisp (from a DVD point of view) and there are minimal macro
blocks (if dvd was done very well.. there are lots that are done poor, and
you can spot many flaws in those) but dvd's are not lot cable/satellite, which
is much lower bitrate, lower mpeg-2 quality. That's your other problem,
and also, some stations jimmy the quality even lower.

So, you see, there are lots of good reasons why you can't obtain the same level
of quality from your home-brew sources vs. commercial sources.

-vhelp

[schematic2]

Thanks vhelp, that explains alot. There was more to it than one thinks...
I get acceptable quality when I transfer Camcorder DV to DvD. If I use CBR of 8000, its fine (I get 1 hour). If I resort to VBR to squeeze 2 hours on a disk, I see artifacts. Is it because of encoder quality, or a combined factor of what you've stated?

[bugster]

schematic2, when you shoot your home video, do you hold the camera in your hand or use a tripod. I bet you hold it, just like the vast majority of home videographaers.

Hand held cameras cause camera shake. Even if you can't see it when watching the video, your mpeg encoder can. The encoder sees this as motion and this uses up precious bitrate. This is (probably) why you see artefacts when encoding your home video at anything but the highest bitrates.

[schematic2]

you are right bugster, its the high motion scenes that I'm looking at. So since movie makers don't have issues with high motion scenes, do we attribute that to their equipment, compression technology or both. Where is our bottleneck?

[vhelp]

hi schematic2,

I was gonna post a 2nd time last night, but I got too tired and deleted.

Anyways.. The bottleneck, well, is not actually a such.

It's more these two mail factors:

01 - Noisey source
02 - resolution

as for line 01, you are dealing w/ (as I discussed earlier above) sources
that are already in compression form. They are MPEG (which is compressed)
..assuming your source is say, cable or satellite.. and there are many other
issues/factors to know, when dealing w/ these types of two sources.

* Cable and Satellite both send MPEG sources (this is compression) that is,
...their sources on their end is MPEG. Then, they jimmy (if they need to)
...their source, BEFORE then air it. Then, when you capture it, you have to
...deal w/ Noise in your (ie, pc; cpu; chipset; mobo; areal; cables; groud;
...etc, etc) and by the time you get it inside your capture card and onto your
...pc, that is your end result. When you view your cable or sateliite on your
...tv set, in your opinion, its as prestine as it can be. And, from your opin..
...that is the best source, and you want to duplicate it, at that best stage.
...The problem is, you can't. You can get close, and can even fool most of
...the people out their, but won't ever get the same.

* Satellite is a little different though. Because there are a number
...of devices that allow (indirectly, via hack) to obtain the source materials,
...assuming that they are not compressed again onto the device (ie, harddrive)
...Here, you might approach the same level of quality. But, even this will
...require your intervention to edit. In the short, editing "equials" re-
...encoding. However, for instance, you could use an MPEG cutter/joiner to
...editing out certain parts of the source and author as such, but even this
...aproach has issues (ie, left-over artifacts) MPEG2VCR is a known app
...that will give you this flexibility. But, beware of left-over artifacts
...during your cutting/joining (at least in my experience, there were some)


DVD has very little noise, if at all. I'd like to say, has none :P

Even if you capture from it (assuming you had the perfect setup) you cold
get great to excellent results. Why ???

Well, because there is no noise. There is no 2nd or 3rd generation compression
or editing or jimmying of the source. You have no tampering of the source.
Only what the pros used to author or add in any special effects etc.

Below is an example of what to expect in your sources when you obtain it
through capturing (analog or dv) - (prior to capturing, that is)

DVD - - - - 1st, generation compression
VHS - - - - 1st, generation compression
LD - - - -- 1st, generation compression
Cable - - - 2nd to 3rd, generation compression
Satellite - 2nd to 3rd, generation compression

Then, after capturing...

Now, given thea bove, this is assuming prior to capturing. Capturing will
in effect add (to an extent) another level of "generation compression"
To eliminate a possible "generation compression" from your capturing of the
surces above, you could therefore, incorporate a "uncompressed" mode in your
capturing. Hufffy might do, but I feel it is still an "generation compression"
DV is unfortunately, unavoidable a "generation compression".

So, now lets look at our list for our DV project of capturing (ie, advc) of
which now becomes:

DVD - - - - 2nd, generation compression
VHS - - - - 2nd, generation compression
LD - - - -- 2nd, generation compression
Cable - - - 3rd to 4th, generation compression
Satellite - 3rd to 4th, generation compression

Now, we need to possibly edit the source. If we need to do this, there is
the possiblility of incrpoing another "generation compression" <- (GC)
(or, also known as, "colorspace") via a codec or resampling. Consider this as GC
Then, you either frameserve this (avisynth or vdub) into your encoder sofware.

SO, now lets look at our list for our DV project of capturing (ie, advc) of
which now becomes:

DVD - - - - 3rd, generation compression
VHS - - - - 3rd, generation compression
LD - - - -- 3rd, generation compression
Cable - - - 4th to 5th, generation compression
Satellite - 4th to 5th, generation compression

Just to note w/ DVD projects...

If you rip your dvd (instead of capturing it) this is how it would most prob
result (which is always the better way w/ quality output)

DVD - - - - 2nd, generation compression

This is due to the fact you encoded it to MPEG.. and assuming you did not
have to apply any codec or colorspace or resampling etc etc via your editing
stage. otherwise, it would look something like this:

DVD - - - - 3rd, generation compression

But, lets say that your DVD-rip resulted in a 3rd "generation compression"
scenario. That's still ok, because the quality of the source was not put
though an major compression (such as cable/satellite does) The dvd-rip is
still prestine (to a point) w/ no noise or mpeg artifacts to be found.

LD's very closly share this same result as DVDs do. But, because you still
have to capture it, there could be a:

LD - - - -- 3rd or 4th, generation compression


So, all about the source level first. Where did you obtain it, and at what
level of quality is it.
What is a DVD rip, DVD capture, LD capture, VHS capture, cable/satellite
capture etc etc. DVD's will be the only ones that can approach the same
output quality as the DVD (or very close, in the pros eyes) But, as for
the LD; cable/satellite; and VHS, you really have to watch where they are
coming from. cable ad satellite will always be compressed, in mpeg form.
.
.
So, when you watch for example, satellite, and even though it looks great
in your eyes, it's MPEG. When you watch it on your tv set, watch the tv
screen and notice any square pixles. if you see them anywhere's, you have
an MPEG source on your screen :P which means, that the source is compressed
to MPEG.

Ok, here is a perfect example, but will cost you approx $20. To demonstrate.
Hopefully, you've watched Sci-Fi's Farscape. This is an excellent
show. The quality is not that bad on tv, but watch it on satellite (I
think they took it off, but you can spot it on late fri/sat nights 2am)
Then, go out and buy the DVD disk. Notice had crips and rich/colorful the
DVD's video quaity is. I leave this test up to you :P
But, by performing this test, then everything I layed out to you in my
above discussion, will demonstrate to you the reasons why you cannot
obtain the same level of quality!

That's about it,
-vhelp