> Rats...my memory of the conversation was that TOP_FORWARD was
> necessary to correct DV of telecined video.

        And for a long time that was the prevailing method - but I ran into
        problems back (3 or 4 years).  

> (I searched the
> mailing list archives, by asking Google for "TOP_FORWARD
> site:mail-archive.com", but couldn't find why TOP_FORWARD was harmful.)

        I took a quick look and saw bits/pieces of the threads but not parts
        I was looking for.  Try searching for yuvkineco and yuvcorrect

        I've got to get out the door and don't have time to do much more than
        clear out the mailbox.  

> As an experiment, I tried running yuvkineco on video without
> doing TOP_FORWARD, and it was visibly worse.=A0 Maybe that's
> because yuvkineco is top-field-first only?=A0 It didn't seem to
> complain about being given bottom-field-first video.
        
        Hmmm, I thought yuvkineco would complain about the wrong field order


> The reverse-telecined videos I make with yuvkineco TOP_FORWARD
> look great to me...and I thought I was nitpicky about these
> things.=A0 :-) Have I been living a lie?=A0 What should I be doing?

        SHift the video one line up or down within the frame.  This is MUCH
        better (I think) than shifting the video 1/2 frame.  Here's what I 
        wrote up about 3 years ago:

#!/bin/sh

N=rites

# NOTE: lie and say it's a progressive stream instead of bottom first.  This
#       hushes y4mscaler and we will tag the stream as top first anyhow after
#       shifting down 1 line.
#
# Take the first 479 lines of a frame and place them in the last 479 lines
# of the output frame.  This places 1 black line at the top and converts the
# stream from bottom to top field first:
#  y4mscaler -v 0 -I active=704x479+8+0 -O sar=src -O size=704x480 -O align=BC
#
# OR
#
# If 720x486 input we can skip one top line and take the next 480 lines:
#    y4mscaler -v 0 -I active=704x480+8+1 -O sar=src -O size=704x480
#
# -A ${N}.wav as needed.

qttoy4m -i p -a 10:11 /Volumes/TEMP/tmp/${N}.mov | \
 y4mscaler -v 0 -I active=704x480+8+1 -O sar=src -O size=704x480 -O align=BC | \
 yuvdenoise -t 4,6,6 | \
 yuvcorrect -v 0 -T INTERLACED_TOP_FIRST | \
 yuvkineco -F 1 -C yuvkineco-${N}.txt | \
y4mtoqt -a /Volumes/TEMP/tmp/${N}.wav -o /Volumes/RAID/TEMP/${N}.mov

        and with that I'me off

        Steven Schultz
>yuvkineco is top field first only.

>[...]

>yuvcorrect top_forward is harmful.



Rats...my memory of the conversation was that TOP_FORWARD was

necessary to correct DV of telecined video.  (I searched the

mailing list archives, by asking Google for "TOP_FORWARD

site:mail-archive.com", but couldn't find why TOP_FORWARD was

harmful.)



As an experiment, I tried running yuvkineco on video without

doing TOP_FORWARD, and it was visibly worse.  Maybe that's

because yuvkineco is top-field-first only?  It didn't seem to

complain about being given bottom-field-first video.



The reverse-telecined videos I make with yuvkineco TOP_FORWARD

look great to me...and I thought I was nitpicky about these

things.  :-) Have I been living a lie?  What should I be doing?



Steven Boswell






      
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