Should i Deinterlace before or after scale, in mediapipe?

[pants]

Should i Deinterlace before or after scale?

does it matter or go faster one way over another??

i go

file browser
qt decode
scale
deinterlace
mpeg encode


i just didn't know what was the best way to set it up.


thanks

pants

[havema-1]

I haven't used the deinterlace pipe at all. If I want progressive output I have just used:

PAL:
scaler : High Quality scaling to 480x576
ppmtoy4m: -v 0 -S 420_mpeg2 -F 25:1
mpeg2enc: -v 0 -f 4 -F 3 -n p -a 2 -b 2500 -I 0 -r 16 -q 7

NTSC:
scaler : High Quality scaling to 480x480
ppmtoy4m: -v 0 -F 30000:1001
mpeg2enc: -v 0 -f 4 -F 4 -n n -a 2 -b 2500 -I 0 -r 16 -q 7

and for interlaced output:

PAL:
scaler : High Quality scaling to 480x576
ppmtoy4m: -v 0 -S 420_mpeg2 -L -I b -F 25:1
mpeg2enc: -v 0 -f 4 -F 3 -n p -a 2 -b 2500 -I 1 -r 16 -q 7

NTSC:
scaler : High Quality scaling to 480x480
ppmtoy4m: -v 0 -L -I b -F 30000:1001
mpeg2enc: -v 0 -f 4 -F 4 -n n -a 2 -b 2500 -I 1 -r 16 -q 7

Note that to encode interlaced video at the moment (200211), you must set and save the high quality bit in the input QuickTime file with QuickTime 6 Player by opening the file in QuickTime Player Pro and selecting Movie/Get Movie Properties/Video Track/High Quality/High Quality Enabled. Disable the high quality bit if you want progressive video.

p.s. My SVCD on a Macintosh memo and cookbook is at:

<http://www.sjoki.uta.fi/~shmhav/SVCD_on_a_Macintosh.txt>

[sterno]

Not sure about speed or mediapipe, but I've heard that it's always better to deinterlace before doing any kind of vertical resizing (regardless of software). Deinterlacers tend to have trouble with something that's been scaled because the line spacing usually won't be consistent anymore.

[havema-1]

sterno is right. Deinterlace before scaling.

Previously I had not used the deinterlacer because due to a bug/feature in MediaPipe: If the input (DV-encoded) QT file's high quality flag is not set, then the deinterlacer is not needed. New versions of MediaPipe may correct this so it is a good practice to use a Deinterlacer pipe.

BTW, how does the MediaPipe deinterlacer work? Does it duplicate or interpolate the omitted field, does it use adaptive deinterlacing?

So currently I encode progressive SVCD like this:

Set and save the input QuickTime file's high quality flag (this yields slightly better output, maybe due to different deinterlacing method in QT vs MediaPipe). Set MediaPipes as follows:

PAL:
File Browser: [choose the input file]
QuickTime Decoder
Deinterlacer
Scaler : High Quality scaling to 480x576
MPEG Encoder:
ppmtoy4m: -v 0 -S 420_mpeg2 -F 25:1
mpeg2enc: -v 0 -f 4 -F 3 -n p -a 2 -b 2500 -I 0 -r 16 -q 7

NTSC:
File Browser: [choose the input file]
QuickTime Decoder
Deinterlacer
Scaler : High Quality scaling to 480x480
MPEG Encoder:
ppmtoy4m: -v 0 -F 30000:1001
mpeg2enc: -v 0 -f 4 -F 4 -n n -a 2 -b 2500 -I 0 -r 16 -q 7