Archived from groups: rec.video.desktop (More info?)
Some quick background (numbered questions at the end). I was
converting analog video from my Sony Hi8 camcorder to DVD video using
an AverMedia DVD EZMaker PCI card (NEC 7130 chip version) and noticed
that people seem to be a bit fatter on the DVD than in the original
video. To confirm this, I shot some video of my entertainment center
(for lots of fixed vertical and horizontal lines), converted it to DVD
using my normal method (captured using VirtualVCR, encoded to MPEG2
using TMPGEnc, authored using Pinnacle Studio 8, and burned to DVD)
and compared the original video played back on the TV with the
resulting DVD played back on the TV. Vertical lines in the DVD were
shifted and farther apart than in the original.
I posted a message titled "Captured video slightly stretched
horizontally" to this newsgroup (see
http://groups.google.com/groups?hl=en&lr=&threadm=b0188aad.0410250843.6fe720b4%40posting.google.com&rnum=1&prev=/groups%3Fhl%3Den%26lr%3D%26q%3Ddejatom2002%26meta%3Dgroup%253Drec.video.desktop.*)
and eventually got a very excellent reply that pointed me to the
analog capture guide at doom9.org
(http://www.doom9.org/capture/start.html), particularly the section on
the capture window (http://www.doom9.org/capture/capture_window.html).
Through a series of tests, I found that my capture card's capture
window is really only approximately 704x480, even though the output
from the capture card driver is 720x480. The doom9.org article helped
me figure out how to use the VirutalDub "resize" filter to get the
aspect ratio correct again by squeezing the stretched 720x480 data
back into 704x480 and adding black vertical bars. So far, so good.
BUT - it occurred to me that with all the settings in TMPGEnc, I
SHOULD be able to get the same result without going through the
VirtualDub step. So I tested again. When encoding, I tried every
combination/permutation of "Source aspect ratio" set to "4:3 525
(NTSC)" or "4:3 525 (NTSC, 704x480)" and "Video arrange Method" set to
"Full Screen", "Full Screen (keep aspect) ratio", "Center", or "Center
(keep aspect ratio)". Against all intuitive logic, the results were
IDENTICAL when played back on the T.V. After much usenet searching, I
finally found an article that suggested using a "Video arrange Method"
of "Center (custom)" set to 704x480, and that worked (added black bars
on each side that resulted in the proper aspect ratio when played back
on the T.V.).
1. Why does a "Video arrange Method" of "Center (custom)" set to
704x480 produce different output than simply using a "Video arrange
Method" of "Center (keep aspect ratio)" when the "Source aspect ratio"
is set to "4:3 525 (NTSC, 704x480)"?
2. Does anyone know anything about the algorithm TMPGEnc uses to
resize the image when using the "Center (custom)" video arrange
method? Will it produce better/same/worse quality than using
VirtualDub's "Precise bicubic" resize filter?
Some quick background (numbered questions at the end). I was
converting analog video from my Sony Hi8 camcorder to DVD video using
an AverMedia DVD EZMaker PCI card (NEC 7130 chip version) and noticed
that people seem to be a bit fatter on the DVD than in the original
video. To confirm this, I shot some video of my entertainment center
(for lots of fixed vertical and horizontal lines), converted it to DVD
using my normal method (captured using VirtualVCR, encoded to MPEG2
using TMPGEnc, authored using Pinnacle Studio 8, and burned to DVD)
and compared the original video played back on the TV with the
resulting DVD played back on the TV. Vertical lines in the DVD were
shifted and farther apart than in the original.
I posted a message titled "Captured video slightly stretched
horizontally" to this newsgroup (see
http://groups.google.com/groups?hl=en&lr=&threadm=b0188aad.0410250843.6fe720b4%40posting.google.com&rnum=1&prev=/groups%3Fhl%3Den%26lr%3D%26q%3Ddejatom2002%26meta%3Dgroup%253Drec.video.desktop.*)
and eventually got a very excellent reply that pointed me to the
analog capture guide at doom9.org
(http://www.doom9.org/capture/start.html), particularly the section on
the capture window (http://www.doom9.org/capture/capture_window.html).
Through a series of tests, I found that my capture card's capture
window is really only approximately 704x480, even though the output
from the capture card driver is 720x480. The doom9.org article helped
me figure out how to use the VirutalDub "resize" filter to get the
aspect ratio correct again by squeezing the stretched 720x480 data
back into 704x480 and adding black vertical bars. So far, so good.
BUT - it occurred to me that with all the settings in TMPGEnc, I
SHOULD be able to get the same result without going through the
VirtualDub step. So I tested again. When encoding, I tried every
combination/permutation of "Source aspect ratio" set to "4:3 525
(NTSC)" or "4:3 525 (NTSC, 704x480)" and "Video arrange Method" set to
"Full Screen", "Full Screen (keep aspect) ratio", "Center", or "Center
(keep aspect ratio)". Against all intuitive logic, the results were
IDENTICAL when played back on the T.V. After much usenet searching, I
finally found an article that suggested using a "Video arrange Method"
of "Center (custom)" set to 704x480, and that worked (added black bars
on each side that resulted in the proper aspect ratio when played back
on the T.V.).
1. Why does a "Video arrange Method" of "Center (custom)" set to
704x480 produce different output than simply using a "Video arrange
Method" of "Center (keep aspect ratio)" when the "Source aspect ratio"
is set to "4:3 525 (NTSC, 704x480)"?
2. Does anyone know anything about the algorithm TMPGEnc uses to
resize the image when using the "Center (custom)" video arrange
method? Will it produce better/same/worse quality than using
VirtualDub's "Precise bicubic" resize filter?
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