[MPlayer-users] MEncoder: Low frame rate on capture from tv
Anurag Mehra
mehra at che.iitb.ac.in
Mon Jan 6 02:58:45 CET 2003
Hello everyone
This mail is to seek help for a very unexpected problem. When I capture
from a v4l source like tv tuner the frame rate is really low:
at 704x576 it is 4 fps
at 352x288 it is 8 fps
at 160x120 it is 25 fps
The command line I use is:
mencoder -tv
on:driver=v4l:width=352:height=288:input=2:norm=PAL:channel=europe-west
-ovc lavc -lavcopts vcodec=mpeg4:vbitrate=900 -oac mp3lame -lameopts
cbr:br=128 -vop pp=lb -o mtest.avi
(load shoots above 2.0)
The problem persists even when I use -ovc rawrgb and -oac pcm so the
problem has probably very liitle to do with compression but has to do
with capture itself.
I think that the hardware that I have is powerful enough to capture and
encode in real time. The hardware/software is:
Intel 850 motherboard, 512MB RDRAM, P4 2 GHz CPU and 80 GB IDE (7200 rpm)
hard disk, MATROX marvel G400 with tv tuner, running redhat 8.0.
Interestingly, when I just watch tv using the command:
mplayer -tv
on:driver=v4l:width=352:height=288:input=2:norm=PAL:channel=europe-west
-vo xv
the motion is very jerky and blocky, just the way the captured avi file
looks. The CPU usage hovers around 70 to 80% and the machine load crosses
2.0!
In contrast xawtv work very well and mjpegtools based capture also
works flawlessly (dma is enabled, so write speeds is not a problem). Main
actor (macap) also works fine.
However, transcode, avicap also capture just like mencoder: giving very
low frame rates and consequently very jerky video. avicap shows lots of
dropped frames, perhaps 70% or more.
Mplayer, in general, seems to work quite well on all the video output
options (x11, xv, xmga etc) when playing all kinds of files and dvds.
Have checked everything that I came across but am unable to figure out
what can be wrong. I thought that with the hardware in question I could
easily capture at 25 fps and encode to divx4 or xvid at a resolution of
(greater than?) 352x288 in real time.
Would be very grateful for tips and experiences that others may have had
in this regard.
Thanks
Anurag
_____________________________________________________________________
Dr. Anurag Mehra, Professor
Department of Chemical Engineering, Indian Institute of Technology,
Powai, BOMBAY 400 076, INDIA
_____________________________________________________________________
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