[Mplayer-cvslog] CVS: main/DOCS documentation.html,1.320,1.321
Jindrich Makovicka CVS
henry at mplayerhq.hu
Tue Oct 29 11:09:13 CET 2002
Update of /cvsroot/mplayer/main/DOCS
In directory mail:/var/tmp.root/cvs-serv28926
Modified Files:
documentation.html
Log Message:
updated v4l section
Index: documentation.html
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/documentation.html,v
retrieving revision 1.320
retrieving revision 1.321
diff -u -r1.320 -r1.321
--- documentation.html 28 Oct 2002 00:44:17 -0000 1.320
+++ documentation.html 29 Oct 2002 10:09:10 -0000 1.321
@@ -198,7 +198,8 @@
<LI><A HREF="#tv">2.5 TV input</A>
<UL>
<LI><A HREF="#tv_compilation">2.5.1 Compilation</A></LI>
- <LI><A HREF="#tv_examples">2.5.2 Examples</A></LI>
+ <LI><A HREF="#tv_tips">2.5.2 Usage tips</A></LI>
+ <LI><A HREF="#tv_examples">2.5.3 Examples</A></LI>
</UL>
</LI>
</UL>
@@ -942,10 +943,6 @@
TV tuner</B>. See the man page for a description of TV options and keyboard
controls.</P>
-<P><B>THIS CODE IS CURRENTLY NOT BEING WORKED ON! Do not expect it to work
- without tweaking/experimenting!</B></P>
-
-
<H3><A NAME="tv_compilation">2.5.1 Compilation</A></H3>
<OL>
@@ -957,28 +954,127 @@
xawtv.</LI>
</OL>
-<BLOCKQUOTE>
- <B>Hint</B><BR>
- Are the colors messed up? Then your tuner cannot display
- in YV12 colorspace. Try I420 (<CODE>-vc rawi420</CODE>) or YUY2, UYVY, RGB32
- (<CODE>-vo sdl</CODE>) colorspaces.
- You can specify these with the <CODE>outfmt=YV12</CODE> option, see below.
-</BLOCKQUOTE>
+<H3><A NAME="tv_tips">2.5.2 Usage tips</A></H3>
+The full listing of the options is available on the manual page. Here
+are just a few tips:
-<H3><A NAME="tv_examples">2.5.2 Examples</A></H3>
+<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>
+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>
<P>Dummy output, to AAlib :)<BR>
<CODE> mplayer -tv on:driver=dummy:width=640:height=480 -vo aa</CODE><BR>
<BR>
Input from standard V4L<BR>
- <CODE> mplayer -tv on:driver=v4l:width=640:height=480:outfmt=i420 -vc rawi420 -vo xv</CODE><BR></P>
+ <CODE> mplayer -tv
+on:driver=v4l:width=640:height=480 -vo xv</CODE><BR>
+ <BR>
+
+ A more sophisticated example. This makes MEncoder capture the full
+ PAL image, crop the margins, and deinterlace the picture using
+ a linear blend algorithm. Audio is compressed with a constant
+ bitrate of 64kbps, using LAME codec. This setup is suitable for
+ capturing movies.<BR> <CODE> mencoder -tv
+ on:driver=v4l:width=768:height=576 \<BR>
+ -ovc lavc -lavcopts
+ vcodec=mpeg4:vbitrate=900 \<BR> -oac
+ mp3lame -lameopts cbr:br=64 \<BR> -vop
+ pp=lb,crop=720:540:24:18 -o output.avi </CODE><BR>
+
+ <BR>
+ 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.<BR>
+ <CODE>
+ mencoder -tv on:driver=v4l:width=768:height=576 \<BR>
+ -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=350:vhq:vqmax=31:keyint=300 \<BR>
+ -oac mp3lame -lameopts cbr:br=48 \<BR>
+ -vop scale=384:288,pp=tn/lb,crop=720:540:24:18 -sws 1 -o output.avi
+ </CODE><BR>
+
+ It's also possible to specify smaller image dimensions in the
+ <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><B>Note:</B><BR>
- If you have a TV card with an external audio device and get only a black
- screen, although input works with xawtv or similar, then try to use the
- <CODE>-noaudio</CODE> option. For the example above this would be:<BR>
- <CODE> mplayer -tv on:noaudio:driver=v4l:width=640:height=480:outfmt=i420 -vc rawi420 -vo xv</CODE></P>
+</P>
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