On Tue, 20 Jul 2004, Marc Gregoire wrote:
> > > I'm trying to author lots of slides to a still-show (not a
> > slideshow!) on DVD.
> > > So I need to convert my slides to mpeg stills. I tried several
> > > different parameters for mpeg2enc and came up with
I knew there was something I forgot to ask...
The artifacts (ringing) on the edges of the flowers look similar to
what one can get from scaling. Part of the differences in the two
flower encodings may be due to the method used to scale the images
to the DVD frame size.
What size/resolution are the slides (source .jpg files)? Are they
from a digital camera (or similar source) and being scaled/resized
to 720x576? mpeg2enc of course needs the correct frame size on
input but perhaps the other encoder is doing the scaling in a way
that avoids the artifacts.
Some packages (such as Apple's DVD Studio Pro or Final Cut) will
accept arbitrarily sized .jpg (or .png, etc) files and resize to
the DVD frame size (taking into account non-square video pixels,
chroma positioning and so on). Other encoders such as mpeg2enc
rely on external scaling and I'm wondering if that's where part of
the quality loss is happening;
Are you scaling the data before running jpeg2yuv and if so how is
that being done? Off the top of my head (which means this is
completely untested - but is similar to what I've done on other
projects):
jpeg2yuv -n 1 -f 25 -I p -j original_photo_file.jpg | \
y4mscaler -I sar=1:1 -O sar=PAL -O size=720x576 -O chromass=420_MPEG2 -S
option=sinc:6 | \
mpeg2enc -q 4 -f 8 -I 0 -4 1 -2 1 -D 10 -h -o output.m2v
Note: if you get the sample aspect frame size correct then you
do not need to give "-a 2" or "-n p". Having to give those
options really means the input stream isn't 100% correct
and you're overriding mpeg2enc's protests/warnings.
You can try setting -q to 3 or less but 4 should give good results.
Raising the bitrate from the default of 7500 can be done with
something like "-b 8400".
Good Luck!
Cheers,
Steven Schultz
p.s. as always y4mscaler can be found at
http://www.mir.com/DMG/Software/y4mscaler.html
-------------------------------------------------------
This SF.Net email is sponsored by BEA Weblogic Workshop
FREE Java Enterprise J2EE developer tools!
Get your free copy of BEA WebLogic Workshop 8.1 today.
http://ads.osdn.com/?ad_id=4721&alloc_id=10040&op=click
_______________________________________________
Mjpeg-users mailing list
[EMAIL PROTECTED]
https://lists.sourceforge.net/lists/listinfo/mjpeg-users
