On Mon, 25 Aug 2003, Ray Cole wrote:
> Here's the command line I used on the old one vs the new:
>
> Old Command:
> nice mpeg2enc -f 8 -b ${aRate} -V 230 -n n -s -a 2 -g 6 -G 18 -I 0 \
> -r 24 -4 2 -2 2 -F 1 -p -v 0 -o ${aName}.m2v
>
> New Command:
> nice mpeg2enc -f 9 -b ${aRate} -V 230 -n n -s -a 2 -g 6 -G 18 -I 0 \
> -r 24 -4 2 -2 2 -N 1.50 -Q 1.00 -v 0 -p -F 1 -o ${aName}.m2v
-N 1.5 is a bit aggressive (but is the same as the old -N though),
1.0 would achieve most of the bitrate reduction but better looking
output.
> I also noticed that using either -f8 or -f9 that something wasn't quite
> right with some sort of timestamps. I did a 'mplayer test.m2v
> -ss 15:00' for example and that really took me about 45 minutes into
> themovie (maybe a little further). This worked when I encoded using
> the older version of mpeg2enc, doesn't with the new.
Possible to set the line length to something closer to 80 or so?
That paragraph came out as a single very long line...
The problem's with mplayer's seeking. Mplayer probably isn't
using the timestamps but is instead assuming CBR and a fixed
GOP size and positioning accordingly. With VBR and variable
GOP sizes seeking is a bit trickier - it's (almost) necessary
to sequentially scan the file looking for the correct timestamp.
DVDs produced with the new encoder work flawlessly in standalone
players whereas the older mplex/mpeg2enc did have issues in
that area. Sounds like bugs in the older version interacted
with mplayer to accidentally get the desired result ;)
I'd have to check what the maximum GOP size is for NTSC DVDs -
thought it was 15 intead of 18 but I might be misremembering
that though.
What's the speed of the cpu being used? The command looks
ok and I'd expect somewhere around 6 frames/sec or so on a
2.xGHz system.
Steven Schultz
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