Stereoscopic player observation at DVinfo.net

Frank Stearns · January 31st, 2011, 07:31 PM

I have noticed that the quality of the 3D output when playing raw left and right video files is noticeably higher then the same video after rendering to frame compatible side by side format even if it's rendered to an uncompressed AVI.
This is observed when playing both with Stereoscopic player outputting in checkerboard format to a Samsung UN40C7000 3DTV.
Shouldn't the quality be the same?
After all they are both half res.
The video was acquired with dual Canon HF21s using MXP mode at 60i.

Giroud Francois · February 1st, 2011, 01:51 AM

you said yourself, after rendering.
it doesn't mean because you save uncompressed video that the process has not damaged the data in between. Jpeg, mpeg2 and mpeg4 are very sensitive to resizing and rotating picture.
And possibly you used an application/profile that works "lossy" using to few bits or the wrong format (4:2:0 instead 4:2:2)

Frank Stearns · February 1st, 2011, 12:07 PM

I guess I should have been more specific.
I used Sony Vegas 10ver-c and without modifying in any way,
rendered it in half res side by side format using the Microsoft Codec uncompressed.
The reduction in image quality is very noticeable which surprised me.

Adam Stanislav · February 1st, 2011, 01:46 PM

Quote:

Originally Posted by Frank Stearns

Shouldn't the quality be the same?

No. The checkerboard format combines the pixels from the two images like this:

L1, R2, L3, R4, ...
R1, L2, R3, L4, ...
etc.

The side-by-side half-resolution combines them differently:

L1 + L2 / 2, L3 + L4 / 2, ... | R1 + R2 / 2, R3 + R4 / 2, ...

So the result in quality can be quite different.

Frank Stearns · February 1st, 2011, 04:06 PM

Quote:

Originally Posted by Adam Stanislav

No. The checkerboard format combines the pixels from the two images like this:

L1, R2, L3, R4, ...
R1, L2, R3, L4, ...
etc.

The side-by-side half-resolution combines them differently:

L1 + L2 / 2, L3 + L4 / 2, ... | R1 + R2 / 2, R3 + R4 / 2, ...

So the result in quality can be quite different.

I am displaying them both using checkerboard output.

Adam Stanislav · February 1st, 2011, 11:39 PM

Quote:

Originally Posted by Frank Stearns

I am displaying them both using checkerboard output.

Yes, but in one case your original is not compressed and in the other it is.

Frank Stearns · February 2nd, 2011, 06:22 AM

I see what is happening now.
If I play the left and right files using Stereoscopic Player in checkerboard mode I get a very good image.
If I play the unaltered rendered sbs version in Stereoscopic Player in checkerboard mode, I get noticeably lower quality.
If I play the rendered sbs version with another media player and force the TV into side by side 3D mode the image quality is good again.
Apparently playing half res sbs using checkerboard cuts the resolution once again.
Interesting.

January 31st, 2011, 07:31 PM	#1
Frank Stearns Regular Crew Join Date: Sep 2010 Location: Superior Wisconsin Posts: 62	Stereoscopic player observation I have noticed that the quality of the 3D output when playing raw left and right video files is noticeably higher then the same video after rendering to frame compatible side by side format even if it's rendered to an uncompressed AVI. This is observed when playing both with Stereoscopic player outputting in checkerboard format to a Samsung UN40C7000 3DTV. Shouldn't the quality be the same? After all they are both half res. The video was acquired with dual Canon HF21s using MXP mode at 60i.

February 1st, 2011, 01:51 AM	#2
Giroud Francois Inner Circle Join Date: Feb 2004 Location: switzerland Posts: 2,133	you said yourself, after rendering. it doesn't mean because you save uncompressed video that the process has not damaged the data in between. Jpeg, mpeg2 and mpeg4 are very sensitive to resizing and rotating picture. And possibly you used an application/profile that works "lossy" using to few bits or the wrong format (4:2:0 instead 4:2:2)

February 1st, 2011, 12:07 PM	#3
Frank Stearns Regular Crew Join Date: Sep 2010 Location: Superior Wisconsin Posts: 62	I guess I should have been more specific. I used Sony Vegas 10ver-c and without modifying in any way, rendered it in half res side by side format using the Microsoft Codec uncompressed. The reduction in image quality is very noticeable which surprised me.

February 2nd, 2011, 06:22 AM	#7
Frank Stearns Regular Crew Join Date: Sep 2010 Location: Superior Wisconsin Posts: 62	I see what is happening now. If I play the left and right files using Stereoscopic Player in checkerboard mode I get a very good image. If I play the unaltered rendered sbs version in Stereoscopic Player in checkerboard mode, I get noticeably lower quality. If I play the rendered sbs version with another media player and force the TV into side by side 3D mode the image quality is good again. Apparently playing half res sbs using checkerboard cuts the resolution once again. Interesting.