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@ -964,86 +964,60 @@ The full listing of the options is available on the manual page. Here
are just a few tips:
<UL>
<LI>
Choose some sane image dimensions. The dimensions of the resulting
image should be divisible by 16.
</LI>
<LI>If you capture the video with the vertical resolution higher than
half of the full resolution (i.e. 288 for PAL or 240 for NTSC), make
sure you turned deinterlacing on. Otherwise you'll get a movie which
is distorted during fast-motion scenes and the bitrate controller will
be probably even unable to retain the specified bitrate as the
interlacing artifacts produce high amount of detail and thus consume
lot of bandwidth. You can enable deinterlacing with <CODE>-vop
pp=DEINT_TYPE</CODE>. Usually <CODE>pp=lb</CODE> does a good
job, but it can be matter of personal preference. See other
deinterlacing algorithms in the manual and give it a try.</LI>
<LI>
Crop out the dead space. When you capture the video, the areas at the
edges are usually black or contain some noise. These again consume
lots of unnecessary bandwidth. More precisely it's not the black
areas themselves but the sharp transitions between the black and the
brighter video image which do but that's not important for now. Before
you start capturing, adjust the arguments of the <CODE>crop</CODE>
option so that all the crap at the margins is cropped out. Again,
don't forget to keep the resulting dimensions sane.
</LI>
<LI>
Watch out for CPU load. It shouldn't cross the 90% boundary for most
of the time. If you have a large capture buffer, MEncoder can survive
an overload for few seconds but nothing more. It's better to turn off
the 3D OpenGL screensavers and similar stuff.
</LI>
<LI>
Don't mess with the system clock. MEncoder uses the system clock for
doing A/V sync. If you adjust the system clock (especially backwards
in time), MEncoder gets confused and you will lose frames. This is an
important issue if you are hooked to a network and run some time
synchronization software like NTP. You have to turn NTP off during the
capture process if you want to capture reliably.
</LI>
<LI>
Don't change the <CODE>outfmt</CODE> unless you know what you are
doing or your card/driver really doesn't support the default (YV12
colorspace) . In the older versions of MPlayer/MEncoder it was necessary
to specify the output format. This issue should be fixed in the
current releases and <CODE>outfmt</CODE> isn't required anymore, and
the default suits the most purposes. For example, if you are capturing
into DivX using libavcodec and specify <CODE>outfmt=RGB24</CODE> in
order to increase the quality of the captured images, the captured
image will be actually later converted back into YV12 so the only
thing you achieve is a massive waste of CPU power.
</LI>
<LI>
To specify the I420 colorspace (<CODE>outfmt=i420</CODE>), you have to
add an option <CODE>-vc rawi420</CODE> due to a fourcc conflict with
an Intel Indeo video codec.
</LI>
<LI>
There are several ways of capturing audio. You can grab the sound
either using your soundcard via an external cable connection between
video card and line-in, or using the built-in ADC in the bt878
chip. In the latter case, you have to load the <b>btaudio</b>
driver. Read the <CODE>linux/Documentation/sound/btaudio</CODE> file
(in the kernel tree, not MPlayer's) for some instructions on using this driver.
</LI>
<LI>
If MEncoder cannot open the audio device, make sure that it is really
available. There can be some trouble with the sound servers like arts
(KDE) or esd (GNOME). If you have a full duplex soundcard (almost any
decent card supports it today), and you are using KDE, try to check
the "full duplex" option in the sound server preference menu.
</LI>
<LI>Choose some sane image dimensions. The dimensions of the resulting image
should be divisible by 16.</LI>
<LI>If you capture the video with the vertical resolution higher than half of
the full resolution (i.e. 288 for PAL or 240 for NTSC), make sure you
turned deinterlacing on. Otherwise you'll get a movie which is distorted
during fast-motion scenes and the bitrate controller will be probably even
unable to retain the specified bitrate as the interlacing artifacts produce
high amount of detail and thus consume lot of bandwidth. You can enable
deinterlacing with <CODE>-vop pp=DEINT_TYPE</CODE>. Usually
<CODE>pp=lb</CODE> does a good job, but it can be matter of personal
preference. See other deinterlacing algorithms in the manual and give it a
try.</LI>
<LI>Crop out the dead space. When you capture the video, the areas at the
edges are usually black or contain some noise. These again consume lots of
unnecessary bandwidth. More precisely it's not the black areas themselves
but the sharp transitions between the black and the brighter video image
which do but that's not important for now. Before you start capturing,
adjust the arguments of the <CODE>crop</CODE> option so that all the crap
at the margins is cropped out. Again, don't forget to keep the resulting
dimensions sane.</LI>
<LI>Watch out for CPU load. It shouldn't cross the 90% boundary for most of
the time. If you have a large capture buffer, MEncoder can survive an
overload for few seconds but nothing more. It's better to turn off the 3D
OpenGL screensavers and similar stuff.</LI>
<LI>Don't mess with the system clock. MEncoder uses the system clock for
doing A/V sync. If you adjust the system clock (especially backwards in
time), MEncoder gets confused and you will lose frames. This is an
important issue if you are hooked to a network and run some time
synchronization software like NTP. You have to turn NTP off during the
capture process if you want to capture reliably.</LI>
<LI>Don't change the <CODE>outfmt</CODE> unless you know what you are doing
or your card/driver really doesn't support the default (YV12 colorspace).
In the older versions of MPlayer/MEncoder it was necessary to specify the
output format. This issue should be fixed in the current releases and
<CODE>outfmt</CODE> isn't required anymore, and the default suits the most
purposes. For example, if you are capturing into DivX using libavcodec and
specify <CODE>outfmt=RGB24</CODE> in order to increase the quality of the
captured images, the captured image will be actually later converted back
into YV12 so the only thing you achieve is a massive waste of CPU power.
</LI>
<LI>To specify the I420 colorspace (<CODE>outfmt=i420</CODE>), you have to
add an option <CODE>-vc rawi420</CODE> due to a fourcc conflict with an
Intel Indeo video codec.</LI>
<LI>There are several ways of capturing audio. You can grab the sound either
using your soundcard via an external cable connection between video card
and line-in, or using the built-in ADC in the bt878 chip. In the latter
case, you have to load the <b>btaudio</b> driver. Read the
<CODE>linux/Documentation/sound/btaudio</CODE> file (in the kernel tree,
not MPlayer's) for some instructions on using this driver.</LI>
<LI>If MEncoder cannot open the audio device, make sure that it is really
available. There can be some trouble with the sound servers like arts
(KDE) or esd (GNOME). If you have a full duplex soundcard (almost any
decent card supports it today), and you are using KDE, try to check the
"full duplex" option in the sound server preference menu.</LI>
</UL>
<H3><A NAME="tv_examples">2.5.3 Examples</A></H3>
@ -1085,9 +1059,7 @@ on:driver=v4l:width=640:height=480 -vo xv</CODE><BR>
<CODE>-tv</CODE> option and omit the software scaling but this
approach uses the maximum available information and is a little more
resistant to noise. The bt8x8 chips can do the pixel averaging only
in the horizontal direction due to a hardware limitation.
</P>
in the horizontal direction due to a hardware limitation.</P>