On Sun, Apr 11, 2010 at 09:30:49PM -0700, RC wrote:
> On Tue, 6 Apr 2010 13:55:38 +0200
> Josef Wolf <jw at raven.inka.de> wrote:
>
> > BTW: I've seen various resolution recommendations for PAL varying from
> > 384x288 to 768x576. What is the correct setting?
>
> VHS has full vertical resolution (576), but a bit less than half the
> possible horizontal res (~384). Additionally, you're going to need to
> crop some of that to eliminate black borders and edge noise, but make
> sure you maintain dimentions divisible by 16, and if you're cropping the
> vertical while interlaced, you will require multiples of 32...
>
> That should reduce your bitrate requirements dramatically.
Sorry for warming up this old thread again, but I am still not sure about
the best method.
Here is what I am currently doing:
1. capture:
sudo ionice -c 1 nice -n -20 mencoder tv:// -tv driver=v4l2:width=768:height=576:input=1:fps=25:quality=100:norm=pal:buffersize=100:forceaudio:alsa:adevice=hw.0,0,0:amode=1:immediatemode=0:outfmt=yuy2 -forceidx -oac copy -ovc copy -of avi -endpos 4:10:00 -o $1.avi
here, I try to get the highest PAL resolution from my bt848 based card.
2. encode:
nice mencoder -forceidx -ofps 25 -aspect 4:3 \
-vf yadif=0,harddup,crop=752:560:8:8 \
-mc 0 -noskip -ovc x264 -oac mp3lame \
-x264encopts me=umh:nr=400:partitions=all:trellis=2:crf=20:threads=4 \
-lameopts preset=standard:mode=2 -srate 44100 -o outfile-20.avi
So to avoid scaling (I assume scaling reduces quality) and keep multiples
of 16, I crop to 752x560. But this results in bad aspect ratio.
The next resolution with proper aspect and both axes multiples of 16 would
be 704x528. But that would mean to throw away about 16% of the pixels. I'd
rather not throw away _that_ much.
Any suggestions?
