Line-doubling artifacts with Toshiba SD-4700 on Buster Keaton's "The Playhouse" (1 Viewer)

[Greg Lovern]

I recently got my first HDTV, a used Philips 60PP9601, and just yesterday got my first progressive-scan DVD player for it, a Toshiba SD-4700, replacing our old Panasonic DVD-RV30 interlaced DVD player.

The Philips' internal line-doubler is notoriously bad (I'll be adding an iScan external line doubler soon for laserdisc, TV, etc.), and in the couple weeks I've had it I've seen the sort of liney artifacts it produces when objects on the screen are in fast motion. As expected the SD-4700 did a much better job when we watched a DVD in it last night, which happened to be "Spy Kids 2". The picture looked great and I never once noticed the liney artifacts that are so ubiquitous with the Philips' internal line doubler.

Tonight I watched some old favorites of mine on DVD -- two Buster Keaton shorts from 1921 & 1922, "The Playhouse" and "Cops" (they're on the DVD titled "The General"). The first, "The Playhouse", had liney artifacts similar to, and almost as bad as, the Philips' internal line doubler. But "Cops" had none -- it looked as good, allowing for the film's age etc., as "Spy Kids 2" had looked.

Any idea why the difference?

Thanks,

Greg

 

[Allan Jayne]

Progressive DVD players have* a "two stage" doubler. Almost all don't have any problem with the first stage,which takes flags from the DVD digital video stream to help construct the progressive scan (full frames) by weaving adjacent interlaced fields. If the flags are not there or are incorrect, the player uses its second stage. The second stage could be mediocre.

HDTV TV sets and stand alone doublers have just the second stage which again varies widely in quality. iScan units are extremely good. We could say they have a stage 2a that handles film source (using 3-2 pulldown sensing and optimizing) and a stage 2b that handles live video (using motion adaptive de-interlacing).

If the DVD is not correctly flagged or was not film sourced, the DVD player that continues to use its first stage will produce horrible results. If its second stage is not very good, you still get horrible results.

Video hints:
http://members.aol.com/ajaynejr/viddoubl.htm

*I am told that there is at least one progressive DVD player, the Pioneer 434, that has nothing but a poor second stage. As one reviewer put it, this player is a cheap product to attract the neophyte (Joe Sixpack) who has just the notion that progressive scan is better.

 

[Greg Lovern]

I fixed the problem by replacing the Toshiba SD-4700 with a Panasonic DVD-XP30. Not only are there no liney artifacts on The Playhouse, the picture looks even better with DVDs that already looked good with the SD-4700.

Greg