[MPlayer-users] v4l documentation

[Emmanuel Anne]

On Mon, 28 Oct 2002, Jindrich Makovicka wrote:

>    A more sophisticated example. This makes MEncoder capture the full PAL
>    image, crop the margins, and deinterlace the picture using a linear blend
>    algorithm. This setup is suitable for capturing movies.
>        mencoder -tv on:driver=v4l:width=768:height=576 \
>        -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=900 \
>        -oac mp3lame -lameopts cbr:br=64 \
>        -vop pp,crop=720:540:24:18 -npp lb -o output.avi

Ok, I took the time to test this on my setup. A miro dc10+ to capture
pal frames.

1) outfmt is not detected with my card, I have to force it (rgb16,
rgb24, rgb32 and yuy2 are working...). Maybe it's related to the kernel
driver, but maybe it should be mentioned...

2) The max size of the frame is more 760x576 for pal for me, but it's a
trivial problem (writen in the docs of the driver).

3) My cpu is not fast enough to encode with such parameters !!! I know
it's not directly related to mplayer, but do you have any suggestions
for some faster video codec (which is not mjpeg) ? The cpu is a p3-1Ghz
by the way.
 
>    This will additionally rescale the image to 384x288 and compresses the
>    video with the bitrate of 350kbps in high quality mode. The vqmax option
>    looses the quantizer and allows the video compressor to actualy reach so
>    low bitrate even at the expense of the quality. This can be used for
>    capturing long TV series, where the video quality isn't so important.
>        mencoder -tv on:driver=v4l:width=768:height=576 \
>        -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=350:vhq:vqmax=31:keyint=300
>    \
>        -oac mp3lame -lameopts cbr:br=48 \
>        -vop scale=384:288,pp,crop=720:540:24:18 -npp tn,lb -sws 1 -o
>    output.avi

Well I have hardware scaling capabilities to grab frames, so I do better
without the scale plugin.

Except these little details, this piece of doc is most usefull,
especially the part about interlacing (I thought interlacing was only
relevant for ntsc, excuse me !).

Thanks for your efforts !