[MPlayer-users] About TV/VCR capture quality

[Fabio S.]

Well, now that everything is well configured, I am making many
capturing tests, trying settings suggested in various posts I found using
google and I have some question which didn't find an answer on the
documentation.

1) If I capture raw audio/video

mencoder -oac pcm -ovc rawrgb -tv driver=v4l2:width=384:height=288 -o
test.avi tv://

then when I look at "mplayer test.avi" the video is flipped upside down.
Is this an error? I realized that if I then compress test.avi the
compressed file is flipped again and it looks correct, so I am thinking
that this is a raw encoding "feature", in some sense.

2) If my computations are right, with these settings I should expect to
use 384*288*3*25=8294400 bytes per second of capturing, only for video.
That is, about 29Gb per hour... :-((

Now for compressed encoding. The command is:

mencoder -oac mp3lame -lameopts cbr:br=196
-ovc lavc -lavcopts vcodec=mpeg4:vhq:v4mv:vbitrate=1200
-tv driver=v4l2:width=384:height=288
-o test.avi tv://

This works fine: capturing is smooth, no frames dropped, perfect
audio/video synchronization, correct frame rate (25 fps).
The problem is that I can see too much "compression artifacts"
(square blocks).
3) How to improve? The bitrate seems already quite high and augmenting it
doesn't help.
4) Even if capturing looks correct from the messages, as I said, when
playing back test.avi the audio looks a bit distorted, in the sense that
the quality is good, but it seems that it is played at a (very slight) faster rate
than it should, making  voices a little bit different from the original
(sorry, I can't explain it better in my poor english)
5) Trying to improve video quality, I added the "trell" option, as
suggested on the documentation but capturing gets worse: frame rate slows
down to 15 fps.
6) I guess that when compressing "on the fly" while capturing I can't do
a 2-pass encoding, right?
7) Can someone who makes captures and is satisfied with the results post
his settings?

(the hardware I use is a 1.2GHz athlon, 521Mb RAM)

TIA

Fabio