[opendtv] Re: 3D compressed formats

  • From: "Mike Tsinberg" <mike@xxxxxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 17 Dec 2010 14:19:11 -0500

Thanks Mark!

 

As usual you have a wealth of information!

 

So for broadcasting most popular are side-by-side compression format that is
decoded and delivered through HDMI in one of the HDMI "mandatory" 3D
side-by-side display formats. Since there are only five of such HDMI
"mandatory" formats is it safe to assume that incoming compressed format
will be is the same or similar format as display format? The Blu Ray, for
example, uses "frame packing" HDMI display format. That probably means that
compressed files on the disk are also done in frame packing style. Although
for motion compensated compression encoding that will be a problem. 

 

Mike Tsinberg

  _____  

From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On
Behalf Of Mark Schubin
Sent: Friday, December 17, 2010 1:30 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: 3D compressed formats

 

Hoo-Boy!  What a can of worms!

There are literally dozens of 3D compression formats.  You can download a
poster of some of the pros & cons, as described by Ateme, here (it's the
lower left): http://www.ateme.com/news_events.php5?Arg=153

Before I get into all the options, let me start by saying that almost all of
the 3D being transmitted today uses a straight side-by-side squeeze: both
views squeezed horizontally by a factor of two and placed side-by-side in a
single frame.  That's one of the HDMI 1.4a formats.  The compression of
those side-by-side images is standard.  

Of course, there's a loss of 50% of the horizontal resolution, so Dolby
recommends a variation in which the left-eye image takes alternating columns
of pixels starting with the leftmost, and the right-eye-image takes
alternating columns of pixels starting with the next column.  That way, for
portions of the image with no disparity, there's at least the possibility
that the two eyes' resolution can be additive (although, once the temporal
element of shuttered glasses is added, all bets are off.

Although that's the most common, it's just one form of "frame-compatible"
compression.  In side-by-side, alone, in addition to the simple squeeze,
there are: squeeze & mirror; rotate & squeeze; and rotate, squeeze, &
mirror.  Then there are side-by-side versions based rotated 720p in a 1080p
frame, thus losing both horizontal & vertical resolution, but less of each,
and there are mirrored versions of those, too.  There is also over-under
(with mirrored version), alternating field, alternating frame, column
interleave, line interleave, and quincunx, plus the Sisvel tile format (a
full-sized, left-top, 720p image in a 1080p frame with the right-eye view
broken into pieces surrounding it), something that allows set-top boxes to
deliver 2D from a 3D transmission without doing image processing.  Finally
(in frame-compatible compression), there is anaglyph, with MANY color-pair
combinations, of which the most popular are red-cyan, green-magenta
(Trioscopics), and blue-amber (ColorCode 3D & SpaceSpex).

That brings us to non-frame-compatible (sometimes called service
compatible).  One form takes any of the (non-anaglyph) versions above and
adds a helper signal for restoring the missing resolution.  Then there is
2D+delta (the difference signal representing the disparity of the two
views), 2D+delta+graphics, 2D+depth, 2D+depth+graphics, and
2D+depth+graphics+graphics occlusion.  The +depth formats are useful for
multiview autostereoscopic displays.

Then there are various versions of MVC.

All of these are being experimented with, but the VAST majority of current
3D is simply squeezed side-by-side feeding a single video channel to an
ordinary compression encoder.  According to recent press reports, the
frame-compatible tile format is also picking up steam.

You can find more in slides 106-111 of one of my 3D tutorials, which may be
downloaded here:
http://schubincafe.com/blog/2010/11/more-than-you-ever-wanted-to-know-about-
3d/

TTFN,
Mark


On 12/17/2010 9:46 AM, Mike Tsinberg wrote: 

What are compressed video formats that are used for 3D broadcasting on cable
and satellite? Is there a formal definition or description of compressed 3D
format? HDMI has described 3D only in baseband.

 

Mike Tsinberg

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