Panasonic DVD-H1000 Not Progessive?

If I rember right, Frames on a DVD are stored in a progressive, non-interlaced format. DVD players like the progresive Tosh would just output that progesive image. The DVD players that we now have downconvert the image to an interlaced format.

Looking at the press release for the H1000 ate Yahoo (http://biz.yahoo.com/bw/990819/genesis_mi_1.html), I noticed the following line:

The gmVLX1A integrated circuit (IC) utilizes Genesis Microchip's most advanced vertical/temporal filtering and scaling algorithms to convert interlaced (television-style) video for display on high-resolution, non-interlaced displays.

I looks like this takes the progressive DVD image, puts it in interlaced NTSC, and then line doubles that to get a "progressive" image. Maybe this is why no one is concerned about copyright issues, as it is just like using a line doubouler off of a standard DVD player.

Any thoughts?

--Bill

I had the same thought. It seems monumently stupid to convert P to I to P, but similar things have happened in the past.

Or it may be marketing hype, with the marketing types not understanding that the DVD stores progressive info already, and wanting to highlight the fact that it does output progressive scan.

Bill R.

[Chromy]

Man, you both beat me to it Yeah, DVD is encoded with a progressive 24 fps digital video signal. The player then performs the pulldown to get it to 30 fps (NTSC) and interlaces the signal.

I was excited about this... After reading the press release I see all that this is; a dvdplayer with a built in line doubler. Yes it is outputing a progressive scan image. But it is no different than the output of any other dvd player hooked up to a Farouja line doubler (well except that it is probably lower in image quality... but time will tell.)

It'll be truly impressive when, like Peter aluded to on the news page here, they come with Firewire outputing the progressive scan information straight from the disk.

None of this progressive converted to interlaced converted to progressive and then outputted to a monitor. But before we see that, there are a lot of issues with the studios to work out as we saw with the progressive Toshiba that tried to make it's appearance.

Chromy

The short answer is that DVDs are encoded with interlaced frame-pairs with film sources. And regular DVD players use
a 3/2 pulldown process to take the interlaced fields and convert them to 480i/60 signal that works with all NTSC
displays.

The inverse telecine process digitally "knits" the two interlaced frame fields to perfectly reconstruct the original
progressive scan frame, but with film sources there are only 24 frames per second (30 for video sources) The
progressive scan frames are the repeated to get to the 60Hz refresh rate (72/120 for computer PS-DVD).

So they are stored in interlaced form, but can be digitally merged to be progressive scan without data loss or artifacts,
so DVDs could be considered as progressive media sources as well.

-Dean.

[Chromy]

From Jim Taylor's "DVD Demystified" (a good book btw, one worth a read)
pp-116

DVD-Video can be stored in progressive and interlaced formats. ... Film, which is inherently progressive, is usually stored on DVD as frames along with information to tell the player how to split and repeat the frames as fields.

Then from pp-154 the technical specs for video coding...

24fps (film), 29.97fps (525/60), 25fps (625/50)

notes at the bottom of the page state that the 24fps is progressive with a decoder performing 3-2 or 2-2 pulldown, the information on which the decoder gets from the information mentioned in the passage above.

It looks as if film can and is encoded as progressive scan video. While this is probably only the case on transfers made recently, the signal is there to be exploited by players of the future that can read this progressive scan data and output it directly to a monitor.

The Panasonic DVD-H1000 is not one of these players, and while it'll look good, it still won't be as good as it could be.

Chromy

Chromy,

Your post is in agreement with what I said.

If you have a box of oranges, all cut in half, you could say that you have a box of half oranges, or you could say that you have a box of whole oranges, and both answers would be right.

The encoded MPEG2 data has interlaced fields, set in matching progressive field pairs that together can comprise a progressive frame.

With the exception of video encoded DVDs, all film source DVDs use this interlaced frame-pair process, and there is no better way to create progressive scan output other than inverse telecine until the HD-DVDs come out, so devices like the Panasonic PS-DVD player, and the upcoming lower cost models will be as good as it gets with PS-DVD for a couple years yet.

And I doubt that people will be able to see a visible difference with native 480p recorded DVDs for film sources, when they do come out, because the digital reconstruction is already a lossless process.

-Dean.

[Chromy]

Sorry, I was out of town for the weekend.

I don't know quite how to attack this.

Let's just step through that quote to see if we derive the same meaning out of the printed word... my comments are in parentheses

"DVD-Video can be stored in progressive and interlaced formats (It is possible for a dvd to have progressive video on it as well as interlaced video. I would imagine that video from a video camera would be stored in it's native interlaced format, while video from film and digital cameras is stored as progressive). ... Film, which is inherently progressive, is usually stored on DVD as frames (full frames, not two interlaced half frames) along with information to tell the player how to split (interlacing the progressive signal) and repeat (what type of pulldown needs to be performed) the frames as fields."

DVD's can be encoded with progressive video. The best way to playback a progressive video stream is to run that progressive video straight into a TV that supports it.

Yes, by running a native interlaced video signal through a line doubler into a progressive set will give alot better quality than just the original interlaced video.

One last question, why did the studios ax toshibas player (which output the progressive video untouched) but haven't said a thing about this one? I would argue that it is because this player is nothing more than a DVD player with a line doubler in it. It is because there are DVD's that are encoded with progressive video and the studios don't want that to go through an unprotected output. Line doublers already exist, and the studios can't do anything to stop a manufacturer from putting one of these into a player.

Chromy

If it is true that the Panasonic just has a built in line doubler, then who would buy this player for this feature alone? All of the 16x9 TVs that are out already have line doublers built into them... but a pure progressive image would look better.

Chromy,

Let's not keep going on about the interpretation of various reports on whether or not the DVDs are encoded in either full progressive frames, or interlaced frame pairs. Please.

Because it shouldn't matter if the disc has progressive frames, or if they are split into interlaced frame pairs, and then recombined using an inverse telecine process, because the recombining process is digital, and lossless.

But this should not be confused with simple line doubling, which either buffers the previous fields, or interpolates the missing interlaced fields.

There needs to be a distiction drawn between devices like Toshiba's aborted PS-DVD, and Panasonic's coming PS-DVD, plus all other devices that use the inverse telecine process, as opposed to simple line doubling which produces a flawed progressive scan image.

The reason that Toshiba's PS-DVD was aborted, is the same reason that there has been such a delay in any PS-DVDs coming to market. The inverse telecine frame reconstruction process circumvents the Macrovision encoding on DVDs, and therefore breaks the law. That was why Toshiba withdrew their PS-DVD from market.

The best reports are that there is a DTV compliant version of Macrovision in the wings that works with PS-DVDs, but it's uncertain if it will be implemented in these first released models.

Otherwise, the players might use the hardware copy protection chips that are being introduced in the upcoming D-VHS recorders and STBs, but with no one hardware standard agreed apon so far, this might not be a long-term solution either.

-Dean.

[Chromy]

OK I get it now I misunderstood the method by which they reconstruct the signal into a progressive.

So whereas line doubleing uses a time delay (buffer the fields in memory and then display them as one frame) to put fields together into one frame the inverse telecine process reverses the interlacing in the digital domain, effectivly giving you the original video stream?

Is the output for a progressive encoded DVD using the inverse telecine process at 24fps or is it still at 30? How about the output from a DVD that is encoded interlaced? Does the chip that they use to do this recognize the difference and undo the pulldown too?

What do you think about the possibilities, if Panasonic doesn't include the D-VHS copy protection scheme, that this player will be pulled too. It seems like the same situation with the Toshiba player.

Chromy

Chromy,

-"Is the output for a progressive encoded DVD using the inverse telecine process at 24fps or is it still at 30? How about the output from a DVD that is encoded interlaced? Does the chip that they use to do this recognize the difference and undo the pulldown too?"

As far as I know the inverse telecine process only works with film based sources, and reconstructs to the original 24FPS frames, then with PS-DVD players I believe that it does the 3/2 pulldown to output 60Hz.

With computer based decoders they do a 3/3 pulldown by simply tripling the frames to output 72Hz. Some people who have better displays raise the refresh rate to 120Hz, which is also a multiple of 24. This 3/3, 5/5 pulldown reduces the panning judder, making horizontal pans look smoother.

All other DVD media sources other than film are internally line doubled, but that's a very small percentage of DVDs overall.

-"What do you think about the possibilities, if Panasonic doesn't include the D-VHS copy protection scheme, that this player will be pulled too. It seems like the same situation with the Toshiba player."

Toshiba was pretty much alone when they first brought out their PS-DVD, and so they backed down from the fight. But now DVD is going like gangbusters, and DTV displays are the next big thing. But short of HD loops, PS-DVD would be the best demonstrator of a DTV display's superior capability, and it works with regular DVDs.

So I don't see this year passing without having PS-DVD players available. There are too many manufacturers who have put their PS-DVD products on hold long enough, and something's got to give.

-Dean.

I once found a document with lots of nitty-gritty detail on MPEG & DVDs. (Of course I didn't bookmark it.) There was supposed to be a option where the picture was encoded as a single frame rather than two fields. Unfortunately, the spec managed to make this option impossible to use, so all source material is first divided into odd & even fields and then encoded.

As discussed, the progressive player simply merges the two fields into a single frame before displaying it.

frame (24Hz) : ABCD
fields (48Hz): AeAoBeBoCeCoDeDo
Inter (60Hz): AeAoBeBoBeCoCeDoDeDo
Progr (60Hz): AABBBCCDDD

But what about material that was interlaced to begin with? (Since the two fields are 1/60s appart in time)

AeAoBeBo -> (AeAo)(AoBe)(BeBo)(BoCe) or
(AeAo)(AeAo)(BeBo)(BeBo)?

The decoder might try some comparison rules between the three fields (AeAoBe) to see which matches better.